I built up a Rspberry Pi self-driving car and everything was fine while I collected data for the Neural Net. After NN finished its training, I want to test the system. At the beginning, everything was fine for like 5 mins. After that the left motors of the car won't work anymore. The first thing I thought about is that at least one of the 2 Li ion batteries I use was drained (I use 2 Li ion batteries connected in series for 2 motors and 2 more for the other motors). I measured the voltage of the batteries, and one of them had 0 voltage. I thought fine I just have to charge it...
Well ... it was not so easy. When i plugged the battery in the cell phone and connected it to the charger, the phone won't turn on (even after 10-15 minutes of charging). Read something about sleep mode of a battery and decided to apply some voltage to the battery (used a pack of 1.5V of batteries). After, I measured the voltage, it was around 2.7. I though good, it helped, let me try to verify the fix using the phone, but it still won't turn on ... Re-verified the voltage and it was 0.0 ...again ...
To summarize, if i connect the Li ion battery to a device that would use it's energy the voltage drops to 0.0, when I apply voltage to the battery, its voltage become something like 2.7V and this behavior is repetitive.
P.S. The other 2 battries seem fine. I have no idea what is the issue. The only way I can think of is to buy new ones, but maybe there is something I don't know. Esp that I need this system working on Monday (morning) and today is almost Sunday (the store I buy from is closed)...
I use this type of batteries: https://www.cnet.com/products/nokia-bl-4u-cellular-phone-battery-li-ion-series/specs/
Any help is highly appreciated.