DIY cells tester

Hello !



I made an open-source DIY cells tester based on a raspberry pi which discharges batteries in resistors and record the voltage and current.

You can see the evolution of the voltage, and it records it in one csv file for each battery.



The main advantages comparing to a commercial one are:

• all slots are totally independent
• you can see the precise behaviour of the cell
• you can calculate your own metrics on each cell
• you can easily create statistics on the tested cells from the saved csv files
• you can extend it to manage more cells

The main disadvantages is that the discharge current is not constant, and for the moment you have to charge them manually before beginning the test, but maybe there are others.



You can find it in github:

https://github.com/Geocali/18650_tester



Could you give me your feedback on it ?

Got a bigger version of your schematic? Hard to see with that low resolution. I'd suggest moving to FETs instead of relays, you could even PWM the FETs to approximate constant current (that's what an Opus does). The IRF3710 is a good logic level low resistance, high current FET that is easy to source from eBay/Aliexpress for cheap.

Are you working on adding a charger capability to your device aswell ?

rev0 said:

Got a bigger version of your schematic? Hard to see with that low resolution. I'd suggest moving to FETs instead of relays, you could even PWM the FETs to approximate constant current (that's what an Opus does). The IRF3710 is a good logic level low resistance, high current FET that is easy to source from eBay/Aliexpress for cheap.

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Great, thanks for your advice ! I will try to work on it.
For now I only have this schematic, but I am planning on making it with Kicad when I move to FETs

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bartk said:

Are you working on adding a charger capability to your device aswell ?

Click to expand...

Yes, I would like to add TP4056 cards on it

Looks like and awesome project, can the PI manage more than 4 batteries ?

rolfbartels said:

Looks like and awesome project, can the PI manage more than 4 batteries ?

Click to expand...

You can combine the ADC with a multiplexer (ex 74hc4067) to have more analog channels and to measure more batteries.