Category: DIY

Sonoff mini r2
February 23rd, 2022 by Dr_Kosh

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Using windows 10 & Windows 11 (tested on Windows 11):

  • Click on start and type Windows features click on “Turn windows features on or off”
  • Make sure that both Hyper-V and Windows subsystem for linux are installed
Windows features needed for flashing Sonoff mini R2 with Tasmota firmware
Windows features
  • Click on start and open “Windows Store” and search for wsl ubunty

Current version Ubuntu 20.04 would take few minutes to install

  • Once installed, click on start and type cmd to open command prompt
  • Once in command prompt type: bash to start WSL
  • System is ready, now Sonoff mini R2 needs to prepared
  • Turn off mobile data on your cell phone!!! (you might get an error if it is on and WiFi is on)
  • Put sonoff mini R2 into pairing mode (hold reset button for 5+ seconds) blue light should blink 3 times than pause, 3 times pause…..
  • Open eWeLink app on you phone and do Pairing. Once device is paired, try to switch it on and off. Device should click. Make sure that this works, then proceed
  • Delete device in eWeLink app, that will warn you that it will do factory reset (we need this)
  • Once device is deleted from eWeLink app, put it in ioT mode – press reset button for 5+ seconds, this time we need continues blink. If you get into pairing mode, just press reset for another 5 second for ioT.
  • Now there will be new WiFi SSID available Something like ITEPxxxxxx and some numbers
  • Connect to it, default password is 12345678
  • You should get as IP address, device is on IP
  • Use web browser to connect to and use prompt to change Wifi settings (use your regular home WiFi SSID and password)
  • Once changed there will be prompt that SSID configured successfully.
  • Find out wat is IP address of sonoff miniR2 on your LAN ( I used tool called AdvancedIPScanner, it is free)
IP Scanner for finding IP of  Sonoff mini R2
IP Scanner
  • Now back to WSL (see step 5.)
  • Thanks to Nicholas J Humfrey, we have script that would do this for us
  • Get script by typing:

curl -O

  • Change mod on this script by typing:

chmod a+rx

  • Now we can use script to flash Tasmota, type:

./ –i ipaddresOfDevice        (ipaddressOfDevice is addres we got in previos picture.)

  • Script will run and you should get screen like on picture below, type Y to proceed once asked to “Proceed with flashing”:
IP Scanner
  • Now wait for couple of minutes, then check for new SSID TasmotaXXXXX
  • Flashing is completed.


  • Sonoff Mini R2 – firmware 3.6.0
  • Wifi needs to support 2.4Ghz connections
  • Wsl version 2. (it should work on version 1, did not test)


If you liked this article maybe you will find this one interesting.

Posted in DIY, Home Automation Tagged with:

Server room monitoring
July 28th, 2020 by Chief

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Monitoring temperature and humidity in server rooms are usually tasks for dedicated hardware and software. It is just a case of this stupid COVID situation that called for urgent and somewhat desperate measures. Postal services are not functioning normally, delivery time for everything is uncertain and some things are even impossible to buy. Combined with living in a godforsaken place it`s as Chris Rea would say a “Road to Hell”. This is why I went down this road and put Domoticz and ESP to the task and created DIY server room monitoring and alerting system.

Measuring device with ESP and Tasmota

I will try to make this look more like a guide since there is plenty of applications for this kind of device.

DIY server room monitoring system sensors device parts
This was my starting point

I made this as simple as it can be. I combined the ESP8266 development board with a DHT11 temperature and humidity sensor. It`s what I had at my disposal, maybe in a different situation, I would use DHT21 or BME280 sensor. Here is a schematic:

Schematic DIY server room monitoring system schematic
Device schematic

This is as easy as it can be no need for any explanation except power connections. You can supply power like this or simply use a built-in USB connector on the ESP board. I just put a standard USB connector on the other side so it can draw power from any USB port. I chose this method since I did not want any possibility for data communication if the USB is plugged to a port on the server or something like that.

Getting DIY server room monitoring device in the box

DIY server room monitoring system sensors device

It took 30 minutes to put everything together. Measuring part of the DIY server room monitoring system is finished.

DIY server room monitoring system sensors device

I did not use any extra circuit board since there is only few wires and one resistor. ESP board was big enough to host everything.

DIY server room monitoring system sensors device

At the end I found a transparent box that some kind of hdmi adapter came in and used it as a casing. It fitted perfectly.

Flashing Tasmota firmware on ESP8266

I already wrote here about flashing Tasmota on ESP but I will mention it again. First, get your hands on Tasmota Pyflasher and Tasmota firmware. You will want to use the tasmota-sensors.bin file. That is the only one you need in this type of flashing. Second, connect your esp to your computer and press reset while holding the flash button.

Flash tasmota

First point flasher to the location of the .bin file and chose com port number that your ESP uses. Second, hit “Flash Tasmota”.

Flash tasmota

It should soon report that firmware was successfully flashed and that`s all regarding flashing.

Configure Tasmota to use Wi-Fi

Scan for Wi-Fi networks on your mobile phone. You should see a new SSID with a tasmota_something in its name. When connected to that network, you will get a prompt to sign in. Click sign in and you will get a prompt to enter SSID and password of your network. It will look like the picture below, and it is as simple as it can be.

Configure Tasmota to connect to WiFi
Configure Tasmota to connect to WiFi

First, take note that ESP supports only 2.4 GHz networks. Therefore make sure that your network is 2.4 and not only 5 GHz. Second, if you have two Wi-Fi networks you can also configure the other one as a failover.

Configure Tasmota for sensors attached to ESP

Now your device is connected to Wi-Fi. Therefore go to your DHCP server and check what IP address is leased to your Tasmota device.

DHCP console

Afterwards, enter that address to a browser on the device that is on the same network and you should get the Tasmota web interface. Click on configuration and then configure the module. Under Module type, chose Generic(18). Since we connected DHT11 to D1 open the options next to D1 GPIO5 and find and select DHT11(1). Click Save, and go back to configuration.

Now you should see readings from sensor on the main Tasmota page.

Tasmota main menu

Configure Tasmota and Domoticz to work together

From here we go under the assumption that there is Domoticz up and running. If not, here is the full guide for the setup. On the Domoticz go to Setup -> Hardware and Create Virtual Sensors. (If you already do not have a Dummy virtual switch, create one now).

Now back to Tasmota again. We need to configure it to use MQTT and Domoticz. So under configuration, we first go to Configure MQTT and after that to Configure Domoticz.

In the Configure MQTT, under Host() field type the IP address of your mqtt broker. In most cases it will be on the same machine as Domotics. Therefore it will also be the same IP address.

At this time, we go to the Configure Domoticz menu and if you remember the moment when we created the virtual sensor on Domoticz, now we need its idx. In our case it was 2, therefore we will enter number 2 under Sensor idx 2 Temp,Hum field. Certainly, here is just a coincidence that Sensor idx 2 Temp and the number 2 that we got from Domoticz are the same. For instance, if it were the next sensor created on this Domoticz instance it would be Sensor idx 2 Temp,Hum 3.

Presentation in Domoticz

Virtual sensor in Domoticz

Here we can see how it looks like in Domoticz. Not bad ha? 🙂 Besides that, the real power of this is in notifications. Notification settings look like this.

Sensors notifications

So it will send an email and Telegram message if the temperature exceeds 25 degrees Celsius. Not to enter in explanations why this temp as a trigger, let`s just say that it does a great job for me at this moment. And here is how 24-hour log looks like so you will figure out one of the reasons why I made all this in the first place.

24 hour Temp and Humidity log chart.

For instance in this situation it was necessary to log and visualize data to find the problem, and to be able to document it. Therefore, this little project just did that, and in the end, it will stay, as it proved to be quite useful.

DIY server room monitoring system server room installation.

DIY server room monitoring system server room installation.
DIY server room monitoring system installed in rack
DIY server room monitoring system server room installation.
DHT installed on front (cold) side of the rack

Likewise, here are few more pictures of two devices that I made to just be plugged in the AC utility socket and transmit temperature and humidity. For instance, I used adapters of the old cellphones as a power source and put ESP on top of it with DHT21 outside to avoid it being influenced by the heat that adapter and esp produce.

Once more, thank you for reading.  


Posted in *.*, DIY, Home Automation Tagged with: , , ,

Tasmota ESP8266 Sensor station
February 3rd, 2020 by Chief

How does monitoring Temperature, Humidity, Pressure,  Illuminance, and Air quality sounds like? Well, it sounds great especially if we can do it in under 50 US $ budget, and it even has some basic weather prediction functions, when combined with Tasmota and Domoticz.

Why measure air quality?

We had a situation in the city where people started to get sick with respiratory problems at the mass level and it was obvious that a major problem is the quality of the air. I mean it was noticeable with the bare eyes and nouse but authorities kept saying that air is ok, and they were publishing fake results. Moreover, results were in the form of a statement like “Air quality is at a satisfactory level”. Yes, it is ok if you ar an internal combustion engine with a great air intake filter!

How could air become so bad in a city without industry?

This started happening with the beginning of a heating season, and it was just a coincidence that the city got a brand new heating plant. Well, later we find out that it was not exactly in city ownership. Moreover it is a privately owned and operated, with a nice and lucrative contract. In fact, the new plant is so nice that they shut down former plant (with chimneys like two times higher than those at the new plant) that was owned by the city and the only heating option left is this new monster that uses wood as a fuel. I could write a completely new story on this subject, but I will stop here.

Why Nova SDS011 PM sensor?

I came to learn about it from the necessity. I wanted to see what is going on with the air pollution and I found a bunch of sensors there on the market but did not know where to start. In fact, one independent journalist brought few “Purple Air” sensors and installed them around the city, and the results were catastrophic. For example, they measured 300 – 500 (US EPA PM2.5 AQI ) almost all the time for 2 months. On the other hand, 0 – 50 is ok on their scale and that scale ends with 500.

These purple air sensors cost around 250 US $ so they are not so cheap. On the other hand, you just have to put it on a good spot, connect it to Wi-Fi and power. But it is very enjoyable to build something yourself so, DIY again 🙂 . Just one more comment, authorities said that these “so-called” measuring devices like “Purple Air” sensors are not calibrated, and not attested by their accredited agency so the results were wrong. As soon as they started talking things like that, the air became so pure and enjoyable to breathe that everyone was so shocked and happy to have the opportunity to live under so wise rule.

Joost Wesseling (RIVM) – Air quality measurements using cheap sensors

What convinced me even more that I`m on the right track was Mr. Joost Wesseling from The Netherlands National Institute for Public Health and the Environment, keynote at the Things conference in Amsterdam. If you read this article until now, it means you are interested and I warmly suggest you watch this 25-minute video .

Back to technical stuff…

First, we will make a little bom (bill of materials) containing major parts. After all, we are building a quite complex device. Therefore we must know what parts do we need.

PartPrice US $
1. ESP8266 development board2.8
2. Nova PM sensor SDS011 High precision laser pm2.5 air quality detection sensor module 18
3. BME280 temp hum baro sensor 3V3
4. BH1750 light intensity illumination module 3V2.5
5. 5V 2A power supply3
6. Some wires, cables, connectors, screws, cable ties and a box…10

Regarding tools needed for the job, I used: soldering iron, hot glue gun, small drill, angle grinder, few screwdrivers, cutting pliers, multimeter, smartphone and a computer.

Since I had to order some parts from China, there was not much to do until they came. I was killing some time wondering how to assemble everything together. What will I use as housing? I went through some stuff I had and noticed the old HP Inkjet printer power supply. I opened it and after measuring the size, it looked like everything could fit in nicely. And it did, so this power supply casing was a box for my sensors device.

Nova SDS011 PM sensor
Nova SDS011 PM sensor fitted in the box

First I put everything together to see how it works. I had a doubt regarding connecting two i2c sensors in parallel (doubt was about addressing not about can it work or not). BME280 and BH1750 are both connected to scl and sda pins of ESP, and I did not now will Tasmota firmware be able to discover them both without fine tuning. But it worked like the charm from the start.

Wiring diagram of the Tasmota and Domoticz sensor station with SDS011 air quallity sensor.

Wiring diagram

Wiring diagram
Wiring diagram as simple as it can be

Regarding wiring, SDS011 talks on serial, so RX goes to ESP TX and TX goes to ESP RX. +5 Volt from SDS goes to Vin on ESP with the assumption that you will connect that pin later to the power supply of 5V DC. This sensor working voltage is 4.7 – 5.3 V, so do not connect it to 3 V pin, it is to low and it may affect readings. As always ground goes to ground. BME280 and BH1750 use the I2C bus, so their SCL (Serial Clock) together goes to ESP SCL which is on pin D1, and SDA of both sensors goes to D2 on ESP since it is Serial Data pin. Sensors VCC connects to a 3V pin on ESP. We already know about ground :).

Handling SDS011 while working

Just to mention that it is not a bad idea to cover air inlet and outlet of a sensor while you work around it, especially drilling or grinding, to prevent dirt to pollute sensor. When all rough work is done, remove the covers. Better safe than sorry.

Covered air in and outs of a sensor.

How it fitted together

Since the goal was to make it nonexpensive, and yet durable and to finish it fast, this is what I did regarding assembly. I positioned the Nova SDS011 sensor on one side of the box, put a microcontroller next to it and then made some physical barrier to create a compartment for BME280. The reason I wanted it separated was the intention to remove it from any heat dissipation that the ESP8266 board produces no matter how small it is. That way alteration of the temperature reading would be minimized.

Positioning components inside the box

I made a socket for the ESP development board on the prototype PCB, so it can be removed, or replaced easily without any soldering. After all this sensors unit is a prototype. The micro USB connector on the board is accessible when the box is open in case it is needed. There are markings on board so there will not be the accidental wrong insertion of ESP board.

Socket for ESP development board.
Some in image explanations regarding Tasmota  sensor station with SDS011 air quallity sensor.
Some in image explanations

Installation for test measurements

Tasmota and Domoticz sensor station with SDS011 air quallity sensor.
Sensors device installed just near the roof
Tasmota and Domoticz sensor station with SDS011 air quallity sensor.
Place where I installed device on the house

Well, I had the opportunity to dig in some cables since there is still no facade on the house, and I put a few UTP cables in. I used one for PoE camera, other for sensors device power supply, and since this is the IoT time, I left two more cables to wait for it 🙂 . First, I chose this location thinking, that it is high enough from the ground to prevent dust and some other near ground particles to contaminate sensor readings. Second, it is far enough from the roof to have its heat dissipation mess with the temperature readings. Third, it is enough protected from the rain and both air openings are from the bottom so it should be impossible for rain to get into the device or sensors.


Everything built here is a piece of junk without the software.

Tasmota had been flashed on to the ESP. Tasmota will be sending data from sensors to Domoticz. I will not enter into many explanations here, you can find needed information at those two links. I also uploaded flasher and two needed .bin`s here. Firmware is 7.2.0, and it will be obsolete very soon. I put it for those of you that like shortcuts 🙂 . It will do the job, and later you can upgrade.

Flashing ESP with Tasmota firmware

There are literally tons of information regarding the process out there, but I will put it in very short terms again here. 1. Connect ESP to your computer, figure out what com port is it using and configure Tasmota flasher accordingly. 2. Press taster for entering flashing mode and then press the reset taster on the ESP dev. board. 3. Release the reset taster, and then release the first taster on ESP. 4. Select the tasmota-sensors.bin in flasher and then send it to the device. (tasmota-minimal.bin is needed only if you are doing OTA (over the air) upgrade).

Configure module pins with sensors.

We now need to tell Tasmota, what sensor is connected to which pin on the ESP board. I attached the screenshot of the config and when compared with Wiring diagram it is self-explanatory.

Configure Tasmota module
Configure module for connected sensors

Results from Tasmota and Domoticz

When flashed and configured, here is how Tasmota web interface looks like. You just find its IP address on your dhcp server (it will be showed as sonoff-acb or tasmota-xyz or something like that) and enter that IP address in your browser. It is nice to make a reservation (or static assignment) on dhcp so address stays the same. On that interface you can basically read values from the sensors and configure, backup or upgrade Tasmota.

Tasmota ESP8266 Sensor station
Tasmota ESP8266 Sensor station

This is how the results from Domoticz look like.

But it is not just about reading values that came just now, logging gives the real power…

So, from the PM 2.5 monthly shows some real air quality statistics although my sensors unit is still not operational for a full month. One more thing to remember, this shows pollution in PM2.5 μg/m3 (raw) and the usual standard is US EPA PM2.5 AQI. That means if you are going to compare it to “Purple Air” you need to convert, or at change units displayed on Purple air (it is on the map). Anyway these raw readings converted to AQI are much higher, so you know what to expect.


I wrote this with a simple intention. That is to show how easy to build and inexpensive this kind of sensors unit can be. I hope it serves as a warning and a manual.

If you find this article interesting maybe you should check on this one regarding fixing a “weather unknown” message. Once again, thank you for reading, and if you have any questions or need help, just post a comment. I’ll get in touch with you asap.


Here is a little update on Jully 2020. , a friend send me a few pics of his “do it fast” sensors station. He even added external Wi-Fi antenna for a better connection range.

Posted in *.*, DIY, Home Automation, Micro controllers Tagged with: , , , , ,

February 3rd, 2020 by Chief

Wondering how to add an SDS011 air quality sensor with Tasmota to Domoticz? Here is a step by step guide how to do it.

First, we need to start with the Tasmota configuration. In addition, let`s just assume that we have a hardware sensor like this built. Above all, now we need to configure it.

Flashing ESP8266 with Tasmota Firmware

It is easy so I`l make it as short as possible…

Here are a flasher and 7.2 version bin if you want to start right now. 1. Connect ESP to your computer, figure out what com port is it using and configure Tasmota flasher accordingly. 2. Press taster for entering flashing mode and then press the reset taster on the ESP dev. board. 3. Release the reset taster, and then release the first taster on ESP. 4. Select the tasmota-sensors.bin in flasher and then send it to the device.

Wi-Fi configuration

Further, after flashing just do a regular reset and you are ready for initial configuration. Therefore you need to connect to Tasmota via WiFi as it now acts as a hotspot. For instance, you could use your smartphone to scan for available WiFi networks and you should see one with “tasmota” in a name. Connect to it and it will show you “sign in” message. Click on sign in and it will open Tasmota configuration site. Here are screenshots in a gallery.

When flashed and configured, here is how Tasmota web interface looks like. Just find its IP address on your DHCP server (it will be shown as tasmota-ACB or something like that) and enter that IP address in your browser. It is nice to make a reservation (or static assignment) on DHCP so the address stays the same. On that interface, you can basically read values from the sensors and configure, backup or upgrade Tasmota.

Configure Tasmota Module for the sensors

This should be easy. SDS011 is connected to the Rx and Tx ports of the ESP board. Above all, remember that Rx and Tx need to be crossed (Rx goes to Tx, and Tx goes to Rx). Imagine it like talking. When You talk (Tx)then I Listen (Rx), and vice versa. We are talking about wire connections right now. Now we move to a logical connection. For TX (GPIO1 serial Out) chose from the drop-down menu SDSx1 Tx(101), for the (RX GPIO3 Serial In) chose SDS0x1 Rx (70). In this example, I connected more sensors. It means more pins need configuration. For more info about wiring go to this article.

Configure Tasmota module with pins of SDS011 and other sensors.
Configure module for connected sensors

Configure Tasmota to send data to Domoticz

First of all, Tasmota is not gonna talk directly to Domotics. Therefore you need to have an MQTT broker up and running. Moreover, in most cases, it is a Mosquito and it is installed on the same machine as Domoticz. Under this assumption, we will continue configuring Tasmota. On the MQTT menu, you only need to edit the first field named Host(). There you enter the IP address of your MQTT broker. If it is installed on the same machine as Domoticz than IP address is the same. If you left everything on default values during Mosquito and Domoticz setup, no need to do anything else here.

Configure MQTT for data from SDS011 and other sensors to be sent.
Configure MQTT

Configure Tasmota and Domoticz in pairs

This part can be a little tricky if you do not know how MQTT, and Domoticz work, but I will try to make it clear and in pairs, so it is easier to understand it. First, we will deal with SDS011. Since it has readings of PM 2.5 and PM 10 we will need to create two virtual sensors. Moreover, since the process is the same only one will be shown here. You go to Domoticz website- Setup menu in the top right corner then hardware, and after that chose “Create virtual sensor”.

Domoticz - Add virtual sensor that will  display SDS011 PM 2.5 data.
Domoticz – Add virtual sensor

Then you name it PM 2.5 since it will be for that sensor data, chose “Custom sensor” from the drop-down menu, and add “μg/m3” as axis label as these are the units that sensor actually measures.

Add custom sensor Domoticz for displaying air polution data from SDS011
Add custom virtual sensor Domoticz

This virtual sensor is gonna display data from the SDS011 physical sensor. Meanwhile, next thing to do in Domoticz is to go to Setup/Devices and check the “idx” of the newly created sensor. You can find it at the end of the list or by searching for its name.

Check the idx of newly created virtual sensor that will display SDS011 PM 2.5 data.
Check the idx of newly created sensor

It`s time to follow this setting in the Tasmota Domoticz menu. Idea is to configure tasmota`s predefined value (in this case Sensor idx 7 Voltage/PM2.5 with idx of the newly created virtual sensor named “PM 2.5” in Domoticz. So we enter the value of 192 to that place.

Configure Tasmota for Domoticz

Configure Domoticz setting in Tasmota for SDS011 and other sensor to be sent accordingly.
Configure domoticz setting in Tasmota

Further, I will explain the creating and mapping of a Temp+Hum+Baro virtual switch. Proces is the same, create virtual switch but this time chose like this:

Temperature Humidity Barometer VS
Temperature Humidity Barometer VS

Again check the idx of the virtual sensor on Setup/Devices menu

Temp hum baro idx
Temp hum baro idx

After that, we go back to the Tasmota page and into Domoticz menu and this time set the value of the ” Sensor idx 3 Temp,Hum,Baro” to 148. This has to be repeated for every sensor added, on both sides!

How it looks in Domoticz

If you find this article interesting maybe you should check on this one also. Once more, thank you for reading, and if you have any questions or need help, just post a comment. I’ll get in touch with you asap.


Posted in *.*, DIY, Home Automation, Micro controllers, Tech Tavern Tagged with: , , , ,

Solarstorm DX4S
September 22nd, 2018 by Chief

Some time ago I purchased a Solarstorm DX4S diving flashlight. Price was very tempting and I decided to give it a try. Got mine for 40 $ from Banggood. I must say I was quite skeptical since this was no proven manufacturer like Scubapro or Halcyon, but figured out that I needed a strong lamp for camping anyway so, I decided to order it and then inspect it a little bit. If it looks like it could actually survive high pressures underwater I would take it scuba diving. If it doesn’t look like solid built (no o-rings, plastic instead of the tempered glass protecting the reflector etc.) I would keep it as a home/car/camping lamp. So it would be a win-win experiment.

Solarstorm DX4S

Some useful info about the Solarstorm DX4S

The flashlight is powered by two 26650 or 18650  batteries. If you are going to use 18650, you have to put them into supplied adapters (yes they come in a box with the flashlight). It is a quite big flashlight and it fits the arm great. The switch is big enough, well placed and easy to operate even wearing 5mm neoprene gloves. It just slides up and down. One time up it is on, one more up the flashlight is off. If you hold it pulled up for a moment it will change mode. The flashlight has 3 modes, High, Low, and Blinking or Strobe mode. I have no equipment to measure output lumens. Only judgment was my subjective visual experience and from that part, I`m more than happy.  When you turn it on in a room at night, it scares the shit out of the dark, and the light level is almost like regular lights are on. At first, I could not believe that handheld lamp is producing so much light. The beam is not too wide, and yet not to narrow. It is perfectly balanced and I like it both underwater and on land.

Waterproof construction

At the bottom, there are two o-rings that take care of the keeping water out of the lamp. They do a perfect job since I never saw even a single drop of water between them. It means one ring is enough, the second one is just a safety precaution. Bottom cap has a gold plated contact spring, and I never had a problem with batteries losing contact. When operated on dry, it heats up much after few minutes of working so I think that it is ok to use it on short terms, but it should not be on for a long on dry because there is no water cooling it that way. It is definitely an underwater battery and should be treated that way – with respect.


The flashlight has four CREE L2 U2 emitters, each rated at 2 W, and that would be total  8 W of power. L2U2 has a working voltage of 2.85 volts. If we take in the calc that four of them is 8W / 2.85 V we will come to 2.8 A. Later I will display what I measured, and it will prove that all numbers are ok and real.

Product name:Solarstorm DX4S Diving LED Flashlight 60M
Emitter Type:L2 U2
Material:Aluminum alloy
Total Emitters:4X
Runtime:1h53min,4h20min,7h10min (26650 battery)
Battery Configurations:2 x 18650/26650 battery (not included)
Switch Type:Magnetic resetting switch (change the modes)
Switch Location:body side of the flashlight
Lens:Impact-resistant glass lens
Reflector: Metal smooth reflector
Carrying Strap:included
Waterproof:60 meters underwater.
Weight:374 g without battery
Size:214mm x 55mm x 34mm(length x head x tail diameter)
Solarstorm DX4S

Water resistance

Its declaration says that it is 60 meters water resistant, and I took it to 58 meters. It survived so the manufacturer did not lie. I personally think that it can survive more than 7 bars of pressure but let’s be realistic here, what do you want from a 40 $ flashlight? 60 meters is deeper than most regular users will ever dive, and at that depth, you are entering the technical diving area so you need another kind of equipment. I have it now for two years, used it in APNEA and SCUBA diving, and in general have all positive experiences.

Underwater light performance

Here are a few pictures and video showing how it looks to dive with this lamp. There are pictures from day and night diving, so you can experience how much light it produces, how big it is in the arm, and what do you get underwater in general.

Solarstorm DX4S
Solarstorm DX4S
Solarstorm DX4S
Solarstorm DX4S
Solarstorm DX4S
Solarstorm DX4S

How to carry it underwater

Title of this paragraph may sound stupid and absurd, but on the sea bottom there are plenty masks, knives, lamps, and other objects that belonged to people that “knew how to do it”. I use a double-sided diving carabiner to secure the flashlight. One side I secure to battery hand strap and the other side to my wing`s harness. So it is locked near my right shoulder, and it has enough cord to freely use it, and move around. When not used, or in hand I just put the battery under the belt so it is not just hanging below me, hitting the bottom or making any other type of mess. It`s kind of DIR philosophy and makes a perfect sense.

Power supply

As mentioned before it can be powered by two 26650 or 18650  batteries. As logical 26650 are bigger and can have the larger Ah (Amper hours) capacity so they are the first choice. A good thing about 18650 cells is that you have them in every laptop battery.

18650 laptop cells

Maybe you can remove some of them from an old or damaged battery pack of a laptop computer. Usually, there are 6 or even more cells in a package, and one or a few of them is destroyed, but the rest is working and has the excellent capacity. You only need two of them so you have great chances to get lucky. I scavenged one nonworking Asus battery pack and got 5 out of 6 in working condition. They are in the picture above.


If you have any decent charger, it will do the job for you and test batteries. What I want to say is that if charger start and after some hours finish charging process, the cell is ok. If it displays any type of error, it means the cell is damaged, and you should throw it away and try the next one.

Nitecore Digicharger D2

And remember, there are marked places where it is ok to dispose of the batteries. Anyway there is one thing to be aware, or so to say beware, and that are scum batteries. There are many brands claiming insanely big capacities for just a few bucks. If it sounds too good to be the truth then in most cases it is not, so avoid buying the cheapest batteries. The same thing is a with a charger. I personally use this Nitecore Digicharger D2 ( D4 version has 4 batt slots) and it is a great charger. If you want the best for your batteries this charger will do a great job. Back to the lamp now.

Power consumption

What I measured on high setting is  2.7 A. On the low setting it is 0.86 A. It means that with 18650 cells you can get around 50 minutes of light at full power or a little bit over a 2 hours an low power mode. For 26650 battery type, with 4.2 Ah capacity, it is a little bit more than 90 minutes at high power mode or near 5 hours of light in low power mode. In both cases, it is quite ok for regular dives especially for day open water dives where you do not keep the lamp on the whole time.

 Solarstorm DX4S construction error

I noticed there is something wrong with the flashlight after having it for a few days. I would charge the batteries and put them into the flashlight. It worked like a charm. Then I would leave it be since it is not something I use on a daily basis. After a week or more, when I needed it there was no light coming out. I started to investigate what is wrong. Batteries had no juice. So I taught that I got junk batteries. Shit happens, right? I charged the batteries again, and everything looked fine. But this time I would not fall for the same trick again. I did some measuring and here is what I discovered.

When turned off, the lamp takes about 12.89 mA from the batteries. It must be a driver problem or a construction error, but I did not want to disassemble it. Now that I knew what the problem was it was possible to fight it. So basically it will drain 0.3 A / Day from batteries if you put them inside. For regular 18650 cells, it is draining around 13% of capacity per day. If you charge batteries just a few hours before the dive (and that is the best thing to do), you won’t feel the difference, but if for any reason you can’t do it that way, you need to do something about this problem.

Construction error workaround

The trick is to screw the bottom cap completely and then unscrew it for approximately one turn. When you try to turn it on it will not work, until you screw it back so it won’t drain batteries. Good thing is that at that position of the cap, both o-rings are actually covered inside the cap so water can`t get in. So you have something like safety switch and little more to think about, but it does the job. It is really not a big deal to do it. This is the only objection that I have found for DX4S.

What`s in the box

The flashlight has no hard case or carrying bag, it comes in the cardboard box, with two spare o-rings, adapters for 18650 batteries, and some kind of manual on one piece of paper, and in a Chinese language only. So, you can throw away manual, it is pretty much useless if you don`t eat plenty of rice every day. Let’s just say that it comes packed well enough to survive postal services and that is it. You do not buy a thing like this for its packing, so it`s not so important at the end. English manual would be a nice upgrade, but let us remember, it is just a lamp :). Just one more recommendation at the end. Get some silicone grease and put it on the o-rings. It is a good thing to do once in a while. Summa summarum, this is a great flashlight and you get decent quality for your money. Remember, wherever there is light, there is also something to see, and there are only two things that should come out to the surface from a dive, (except a diver of course 🙂 ) bubbles and photos. Happy diving 🙂

Thank you for reading,


Posted in DIY, Tech Tavern, Video Tagged with: , , , , , , , , , ,

Battery pack with car charger
August 16th, 2017 by Chief

Battery pack changes from version I

This article is the continuation of the first one about DIY power bank. After many field tests, I modified the battery pack a little bit. I started with 3 S and ended up with 4 S pack. With 3 S voltage was a problem, since it was a little bit lower than most 12 V devices are expecting. For example, Blitzwolf USB charger would work when a pack is just disconnected from the charger, but it would start shutting down itself very soon. It was because the device was protecting the battery from over-discharge. It is logical since it is designed for use in the car, and this way it is protecting the car`s battery. So I upgraded the battery pack from 11.1 V to 14.4 V. Connection of the cells is like on this scheme:

Battery pack of 32 cells, 8 cells in parallel, and then 4 times in series

Battery pack = power bank

The power bank is in the essence same device as the battery pack. Different names should not confuse you anymore. Modern marketing gurus just needed something new to sell. So they created a new name for the same device. The name is modern, strong and good sounding, and probably it boosted sales. You may call it however you like, the point is it is the same device.

Second edition

Powerpack contains 32 old Nokia BL-5CT batteries. It is able to completely recharge smartphones from 8 to 15 times depending on the phone type.
So in the end, it looks like this. It is 7 cm wide, 5 cm high and 11 cm long. It weighs 800 grams.
I mounted a standard car lighter plug. It means that the battery pack can power many devices made for in-car use directly. It`s not something that you can carry in your pocket since it is too big, but for longer off the grid occasions like camping it is perfect. It can recharge your phones many times, power up your camping light, DC – AC converter and many other gadgets.

Battery pack
Final version with car lighter socket

Favorite usage scenario

This is my most used scenario for the pack. When on camping I plug in this great Blitzwolf charger, and the whole family is provided with enough juice to recharge phones for a few days. This is the example of reusing technical waste. I had many of these old cell phone batteries and I put them to good use again. I ended up with the capacity of 8 Ah and voltage of 14.4 V. There is also a joy of using your own creation and that is the biggest of all rewards.

Once again, thank you for reading.


Posted in DIY

July 31st, 2017 by Chief

Wartime – how the darkness came.

I was ten years old when I noticed that people around me started talking about us and them. I remember clearly a few situations when some older men asked me: “Kid, what are you?” It was at that time confusing and creepy question for me since I did not understand it. In most cases, I would ignore the question or just answer: “Human being”. When it happened a few times, I asked my parents to explain to me what is the trick with older people asking that weird question. (Later I figured out it was a question about religion). They said that people always try to find reasons to divide among each other and that both my answers were correct. Very soon people became divided by other ways. For example, there were those with electricity and those without it. It was wartime.

Life in a city without  electricity and heating

I lived in a city that had at the time around a quarter of a million people. Infrastructure was ok, for example, there was a big heating plant providing everyone with heating and warm water. I lived on the eighth floor of the building with around 50 apartments. Just try to imagine how it looks to walk to the eighth floor by the staircase without any light! Yes, the building was designed that way, and it was not meant for living in the stone age and without electricity. It had an elevator, but then again it also needs electricity to work. At first, we had some flashlights, but soon we were in a situation that there were no batteries in stores to purchase. Very soon there was no money for them anyway so the first problem could be ignored….. It was wartime.

 First of many problems – heating

The building had very bad insulation. It was hell during summer, and it was a fridge in winter. Without electricity, the fire was the only way of heating. Now that I`m thinking about it, it was the only way of cooking and heating water. So, in time when most of mankind progressed at warp 9, we were solving problems from the like stone age. The parents bought us a wood cooker.

wood cooker

It looked just like this and even had an oven. Our greatest and only home appliance that actually worked. It provided us with heat, enabled us to cook and to heat up some water for bathing. We were almost ready to survive.

Of course, the building did not have a chimney so we drilled a hole in an outside wall and put smoke pipe outside at the building facade. It was the only way, and everyone did it. Soon building with white facade became almost brown, black and gray. It would actually look great in a cheap post-apocalyptic movie. The whole city looked that way…. gray smoke and dark everywhere. But as I said before, now we got ourselves means of heating, cooking, baking bread and producing some hot water. If you would put big enough pot of water on a cooker and heat it near the boiling point, and then empty it in a bathtub and add some cold water, you could almost get a decent bath. In a great necessity, human ingenuity can be limitless.

Acquire firewood in the middle of the city

So the next problem was providing firewood, and stockpiling it somewhere. Well, we had a small storage room in the basement of the building and a decent balcony, so some of the problems were solved. The next one was to buy firewood. It was very expensive, and there was little or no money at all. Anyway, very soon a new type of job and market arises from this trouble. There were horse wagons patrolling the city and selling firewood. Yes, I`m talking about 1993. year, it was not some western movie :). My parents would buy a wagon of wood and we would unload it in front of the building. Then, the fun would start, since it would need to be carried up to the eighth floor. We would start packing woods in a bags and carry some in the basement and some up the stairs. Great recreation huh?

Off and On ratio

At 1993. we were at the point where we would get electricity from the power grid for a few hours every….. 45 days. Yes, that was the on and off ratio. At least for us unlucky enough not to live in the same building with a politician or military officer. Those with that kind of neighbor did not have any power restrictions. Most of the people used candles, and candle market was expanding one. Imagine the whole city in the complete dark, and few scattered buildings shining like a Las Vegas in the dark. It was already possible to conclude that this situation will not end up well. People were leaving their homes and going somewhere. I think it is the first time that I heard word refugees.

How did technology help in a wartime

The first and most common solution that did not involve light sources based on fire was a car battery (if you were lucky enough to have one) and a 12V light bulb. With a bulb from the car main light you would get very good light, but not for a long time, since it was 50 W lamp and that would give 2-3 evenings of light with a standard car battery. It was ok for the beginning of power restrictions when there was no power for a few days. If you had a good charger you could recharge the battery in a few hours and it would do the job. But as it was getting worse and there was no power for a week, the main light bulb was not an option anymore, so the tail light bulb was more appropriate. It was 10 W, and it could last on a single charge for a week or more. It was a time of saving, and energy was the currency.

The neon tube as a life/light saver

Then came the best, most practical and greatest piece of technology of the ’90s – 12 V Neon tube driver, or 12 V CCFL inverter. It would make a standard neon tube shine on a 12 V with acceptable power consumption. Usually, it would drive 10 – 20 W tube, and it would produce much more light for the same amount of current than an ordinary filament bulb. Another great thing was that the neon tube did not need to be in normal working condition. The ones that did not work on normal 220 V surrounding due to the broken filament, would work like a charm on this type of device. It was because of the different way of electrical gas discharge. Now you could create a decent amount of light for a current consumption around 1 A. There were many variations and sizes of these CCFL inverters, The smallest I made worked on 6 V and took 200 mA to drive a small 10 cm neon tube. It was great for the bathroom! I also made some big ones that drove 1,7-meter tubes at their full intensity. Big ones consumed up to 1.5 A but could produce enough light for a very big room or even a cafe bar.

How it was made

Most of the necessary parts could be salvaged from the old BW TVs. Remember, it was wartime and it was not possible to go to Radio Shack and by components. Transistor and ferrite were the most crucial parts and both could be found inside a TV, and suddenly it was a great thing to have one that you did not throw away. Regarding ferrite, I experimented with stick shape, U shape, even pot shape. All worked, but the best was the U shape.

CFFL Inverter schematic

“U” shaped ferrite

Two of the U shapes were in high voltage cascade of the BW TV. I remember that we stripped CuL wire by unwinding old transformers. Capacitors and resistors could be scavenged by disassembling all sorts of electronic waste. Of course, there was improvisation also, the right values were often created by combining multiple elements in series and parallel. You had to put all your ingenuity to work :). The casings could be made out of anything, from food cans to a wooden box.
Device creation could be a piece of cake. Only the transformer took time due to the big amount of windings in the secondary coil. And like always there is a “but” at the end. Soldering iron did not work without electricity either. There were some that could work at 12 V but there was not even enough power for the light so soldering iron had to consume something else to get hot. My father is ingenious as he is used one big old soldering iron in a very specific way. He would put its tip in a fire (we all ready had a wood cooker in our living room) to get it hot enough for soldering, then clean tip a little bit and use it to solder a few wires or joints. Then back to fire again for heating up. That way he was able to create, repair and fix many devices even without electricity.


I wanted to create one for the means of this article, but I made or helped in the creation of so many of them as a kid that I almost puked even on the idea of winding a transformer again.
There is a great passion for electronics in my heart and joy of creating things, but that “survival mode” was a little too much. I think that we created more battery chargers, and CFF drivers than the small factory would do in a year. We traded them for food, wood, money, whatever possible. There is no such misery as the one in a city in times of crisis. When you live in the countryside and have some land, you can at least produce some food. Grow some vegetables and have some animals. On the asphalt and concrete in your 50 square meters, you can`t do anything but starve.

Radio over faucet 🙂

In a time like that even listening to radio would help, and I was trying to find a way to power it.
I tried to create a little generator that would use water flowing from the faucet, but my great idea turned up not to be so great when finally it came to me that someone has to pay for that water also. I was so occupied with that project that I overlooked that fact. So, it was back to the drawing board again.

Radio over phone line

The next “great” idea came to me one time when the phone ringed in the dark. Yes, we had a phone, and it worked most of the time. I still wonder why, but phones worked. They let us use the phones, although you could call only the territory controlled by “ours”. Anyway, I asked my father, how the phone works, when there is no power almost anywhere, and he explained to me that in telecom, they had very big batteries, and generators, so their equipment is always powered up. I measured the voltage on the phone line and it was 9 Volts. The situation was promising! I figured out that I could drain up to 15 mA and the telephone would still work. Great, I had a little radio that worked on 4,5 volts, found 3 AA NiCd accus, connected them in series and idea was to charge them from the phone line, and to let radio work taking power from them. That little radio could work with 10 mA current if it was on very low volume. 25 mA if it was decent volume. And I got to charge accus 24/7 so it would give me buffer to listen to the radio for let`s say 14 hours. Great, it would do the job. One time I was holding phone line wires in my hand and something very unpleasant happened. Somebody called us! It means that some 90 Volts or something like that ended up between my fingers. It was really a nasty feeling, and I threw everything away for a day or so, pissed off for what happened. Those days, the phone would ring once a week or something like that, and it had to happen while I had stripped wires in my hands! Murphy’s law! That is when I learned how telephone works, and rings 🙂 . Anyway, I ended up with that high voltage problem, and I think I used some Zener diodes and resistors to overcome it, but I can`t remember the details anymore. I used my great achievement for a while and enjoyed the radio until parents started wondering why no one is calling us ever. The phone worked, and you could call, but it just did not ring. I knew it was my “genius” device and immediately went to guerilla mode. I would connect a device during the night to recharge my batteries for a little bit, and disconnect it in the morning. This worked, and although I had to make some compromise, I actually had a few hours of music every day. A little bit of happiness in dark times. You know that special feeling when something is taken away from you by force and you finally get a piece of it back. That was it.

Washing machine bath trick

One more tech trick for wartime. If you live in a building without warm water, and without a water heater, you can use the washing machine to heat up some water for you. Here is my father`s genius solution:

Do not put any laundry in the machine.
Do not put any detergent or softener in the machine.
Take the drain hose and put it in your tub.
Set machine for the highest possible temperature program.
When it spins up and gets the water out, you will get much hot and clean water, just add some cold, and there is your bath, great huh?

Once every 45 days we would get those 3 hours of power, so it was a hurry to do what can be done, recharge some batteries, and of course, enjoy almost a real bath 🙂 .

No battery can last for 45 days

It was obvious that you can`t have a battery big enough to provide you with enough Amps to last you 45 days even just for a light.

This battery pack was a lifesaver and I must dedicate a few sentences about it.
This was 10 NiCd cells pack for the RT-20 military mobile radio unit. There is a great site about them at this link. So this battery pack was 12 V, 7 Ah and it was small enough to carry. Father worked at the local radio station as a broadcast equipment specialist and since they had a diesel generator working 24/7 he would take the battery to work with him, recharge it there and then bring it back home again. Sounds crazy from today`s point of view right? Well, this worked, and we had a light problem solved. This was 4-5 Kg, 15 x 35 cm package, so it was not so hard to carry it around. I must say that these were the most durable, rechargeable batteries I ever encountered. They were made for the military by factory “Krusik” in Valjevo, Serbia. Indeed they were a military-grade technology.

Other handy things

There were a few more helpful things in the DIY department.
Alcohol stove made of a can was great for cooking coffee and tea, and even boiling some eggs. Soon there was no coffee and no alcohol for the stove. So it did not last much 🙂 .
The DIY candle was another useful thing to create. You put some oil in a glass and use a piece of cotton as a wick. Wick would go through a bung and piece of metal over it so bung does not burn. Great DIY candle, but it smells bad as it burns.

Eggs of war

I don`t know precisely why, but there is some special connection between wartime and chicken eggs. Sounds crazy? Well as soon as the city was without electricity egg market expanded rapidly. Why? I suppose it was because they are cheap and easy to transport, and do not require much energy to prepare. You could boil an egg even over a candle. It means you would not starve. Eggs were being sold in front of the already closed stores, on the sidewalks, on improvised market places, literally anywhere. I ate so many eggs in those years that I can not look a chicken in the eyes anymore :). So if you ever notice that eggs are selling rapidly around you, it`s time to run away. Try to leave your country and do not look back. War is coming, or it already came. And if you want to be a normal person ever again, then it is not a surrounding for you to be in, or you may end up writing articles like this 🙂 .

Money for nothing

We also had our own currency, and it was something to tell about. What better way to enslave citizens than to take control of the money. How to do it? Invent your own currency and print it yourself. That way you control how much money is out there, and how much does it actually worth. That is also a great way to exchange worthless paper for stable foreign currencies that you will need when you take everything you can and leave the country for some far-away place without an extradition treaty. All that you can do if you are a government or in our case a few man show. Another great thing was inflation. If by any case you would get some money you would need to run to buy something for it or change it to foreign currency asap. Why? Literally, overnight, you would need one more zero for it to be as worth as yesterday.

5000 to 500 millions

Our Monopoly money from 5000 to 500 million.

For example today 1 DM (Deutsche Mark, most popular currency of the time) would be exchanged for 5000 Dinars (Our new patriotic money was called “Dinar”), but tomorrow one Mark would be 50000 dinars. I remember that one time my mother got her monthly salary in those dinars and she could buy a box of matches for it. At that time she at least still had a job. It was real-life Monopoly money, or as Dire Straits would say Money for nothing. Unfortunately, the technology could not help here, but at least we used it to stay in a connection with the rest of the normal world.


I started writing this article in the hope to evoke some old memories regarding my early electronic projects. I also shared some stone-age ideas and memories. Necessity created them, nothing big, great or revolutionary. They made life a little bit easier. Now I`m thinking what would I give at that time for one of today’s led`s? Well, time was different and darkens did not come from the lack of technology but the lack of sanity and humanity. And if you notice that eggs are being sold everywhere, and whenever you see a bill, you begin thinking about Dire Straits, it may be a time to found yourself a new country, because yours may be coming into a war.

Once again thank you for reading.


Posted in *.*, DIY, Tech Tavern

Nokia batteries
May 13th, 2017 by Chief

Electric age is driven by batteries

Most things around us are now powered by batteries. Many devices are powered by similar types of batteries considering voltage and capacity but only packed in different casings. When a device stops working, or there is no need for it anymore you can salvage some parts. In this example, we will use some old Nokia batteries to create homemade power banks. Not a big deal, finished housings  can be purchased for standard laptop cells  in order to create a power bank. You would even get charging electronics and connectors built-in. Well, we will create something different this time. Our approach will be more geek and less conventional duo to the nature of this article.

Why power bank?

Short to say it`s because the batteries are still too inefficient to provide enough juice for today`s devices. Manufacturers sacrificed battery autonomy in order to keep devices as small as possible, retain mobility and keep the performance. The best comparison is between today’s cell phones and the ones from ten or fifteen years ago. Today in most cases you must charge your phone on a daily basis, and back then you would do it once a week. So if you want more autonomy you need a power source, and if located somewhere without access to the power grid, power bank jumps in.
Basically it is a pack of batteries in which you store some energy for later use.

Should you buy or DIY?

PB`s are quite useful to have due to its function and portability. It is possible to buy one in almost every consumer electronics shop or order it online. If you have some tools, basic knowledge about electronics and want to have some fun, you can even make it yourself.
Here is BOM for the job:

Some old batteries (I had 12 pieces of Nokia BL-5 batteries),
Soldering iron,
Soldering wire,
Some wire,
Insulation Tape


Schematic diagram

Block diagram of generic power bank

This is the block diagram of mostly used design for power banks. Manufacturers mainly use laptop cells, 18650 connected in parallel. The capacity of one cell, times number of cells is what they advertise as PB capacity. For example, if inside of a PB are four 2500 mAh cells, it is advertised as  10000 mAh PB.
If you have a PB of 10000 mAh capacity, and your smartphone has a 2500 battery inside, it does not mean that you can charge it from 0 to 100 % of capacity 4 times as logic would suggest. It is closer to say that you will charge it two to three times at most.

Important to know:

Cells in the diagram are connected in parallel. These cells are typically Li-Ion batteries with 3.7 declared Voltage. Most devices have the same 3.7 V batteries. The charger must have a higher potential than the battery. It means that for charging 3.7 V battery you need at least  4 V or 5V sources. This is where the 5V step-up comes in.  If we charge our phone with 5V 1A it means that we are using P=U*I 5W of power. If we take 5 W from a source of 3.7 V it will be 5 W / 3.7 V = 1.35 A. To keep it simple it means that from 10000 mAh PB you get around 7000 mAh of charging. To get back to the example of the phone battery of 2500 mAh it means that you will be able to charge it from 0 to 100 % at most 2.8 times, not considering any losses.

Here is what we did:

12 Batt.

Our Schematic

We took twelve BL-5CT batteries and connected them by the schematic above. So it was four in parallel and then three times that in series.



BL-5 is declared as 3.7 V 1050 mAh, so we connected four in parallel and got 3.7 V 4200 mAh. Connecting three times that in series got us 11.1 V 4200 mAh battery pack. Now let`s look at the Wh or Working Hours. You get that number by multiplying voltage and capacity. 11.1 * 4.2 = 46.6 Wh. If we look at a case from our example of commercial PB it would be: 3.7 * 10 = 37 Wh. Since the Wh is the amount of energy that can be stored into the battery, it is clear that numbers are in favor of our PB and considering we got it from junk and it costed almost nothing, it is a great result, right?

Alltogether connected

Finished PB

Measuring batteries

The voltage of fully charged PB

What to do with it now?

You can power up many things with this power bank,  portable radio, car phone charger, camping light, and many other gadgets and therefore enjoy using them off the grid.

Charging phones

Car phone charger connected to a PB, and charging two smartphones.

Great camping gadget, and works like a charm when powerd by our PB

12 V 15 W led camping light

This Led provides enough light for descent camping area when hanged at 3 meters hight.

LED-Powered by PB, consumes 0.67A

Anyone interested can purchase a similar LED  on eBay for under 5 $. Here is the link for the starting point so feel free to explore if you are interested. Just replace wires and alligator clips when you get it since original ones are to short and to thin.


These batteries have a built-in charging control and when full they will stop taking current. What I usually do is feed them with 12 V power source in series with a 12V 5W light bulb from a car interior light. The light bulb is there for overcurrent protection and you can buy it almost anywhere. You can use any DC charger, or adapter, for example from old external hard hard drive, in general, anything that outputs 12 – 18 Volts and 1 A or more.

Charging batteries by 12 18 V power source in series with light bulb for current limiting

Charging batteries

Word of an author:

I just had some of these old Nokia batteries and therefore did something better than throw them to waste. Since indeed I was in need of a power bank this was a logical choice. It is interesting that these batteries were old and much used, but still found in great shape. I measured that they still have more than 80 % of their stated capacity and that is awesome. I will later install a cigarette lighter socket, like in every car so I can plug in things directly and avoid wires and alligator clips.

Well, it is time to end this story, I hope you find it useful and interesting, and if you have any comments, thoughts, or simply want me to test something, please leave a comment and we will get in touch.
Once again, thank you for reading.


Posted in DIY