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.
Discharging
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.
Charging
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. All help is thanked!

 

There should be a current rating on the side of the cell, they can vary from 3AH to 9.8AH, and they should have a battery monitor pcb, if they get too low-voltage they can be destroyed..

 

There isn't, and there old. Thats why I want to test for the current capacity, because even if they did say it would not be accurate. But doing the math from the rated capacity of the drill pack these should be about 2A

 

Try one of these. Very slick device and well made and it will act as a charger also. I have even used it on bigger batteries and used the 9 amp draw down. The instructions are written in Chinese English so you need to read between the lines to get what they are saying. You will need a 12 volt 1 amp minimum wall wart to power the device.
http://www.ebay.com/itm/Constant-Cu...479e12&pid=100338&rk=2&rkt=30&sd=291980997698

 

Looks interesting. And it is bothering me, what about the fans? remember there 12v at .18 amps. Even thou I am running them at 4v, is it still drawing .18 amps? doesn't seem right...