So since I do not have a battery balance thing yet I have been working, starting yesterday, on some li-ion cells because I need to find capacity of the cells. And I have a few questions to make sure I am doing my math right.
I am using 4 computer fans to discharge the cell. Each fan pulls .18 amps. But there 12v fans and this is a 4v battery. So is the fan still pulling .18 amps a hour? And there is 4 in parallel to pull .72 amps a hour. So how much are they pulling because I am simply not sure. And is there a formula on figuring that out? What would it be? Along with the pull I have a multi-meter on the battery to watch the voltage. There at 4v and discharging to 3v. But have nothing to charge them bringing me to my next part.
The only thing I have is a 5v 1 amp a hour wall charger for a phone. I stripped the wires. All I was thinking of doing was having that directly on the battery and again using a multi-meter to watch the voltage and then stop at 4v. But how long would I expect this to take? Say the battery could hold 2 amps. It would then take 2 hours to charge but I worry that would charge to 5v. So how do I calculate how long it would take to charge to 4v?
The whole purpose is to find the capacity of the battery. Also note these are about 5 years old. Some are good some are not good. Brand new they where able to hold about 2A