Battery Experimentation Part 1

We want to better understand how these LiFePO4 batteries work, so I ordered 4 small hobby cells.  These are the same chemistry and cell voltage as the big battery cells that will make up the truck battery pack, so I think it is reasonable to study these to learn how the big battery will work.

I ordered 4 1300 mAh cells.  These are not expensive at all.  I also ordered a 4-cell charger which was a little pricey but I want to get straight to studying the battery characteristics, not figuring out how to make my own charger (for now). I am going to spend some time charging and discharging these batteries at different rates and observing how the voltage changes over the charge/discharge curve.

I just received these so I haven't done much yet.  They appeared to be mostly charged (reading about 3.3V) so I didn't charge them first.  Instead I hooked them up in series and used it to drive a stepper motor board.  I let it run for a little less than an hour and took periodic voltage readings.  This setup draws about 0.5 A.  Here is a photo:

Discharging 4-cell pack of LiFePO4 batteries

I am going to mount these batteries on something and solder the connections instead of using the clip leads.  But I wanted to try them out so this was the quick way to get started.