Sunday, August 17, 2014
Leaf Module Capacity Testing
I have been testing for capacity on my Leaf Modules I purchased. I built a charge and discharge setup and charged three modules to 8.2 volts and then terminated the charge. No CV holding until the amperage dropped. Just to 8.2 volts which is 4.1 volts per side of the module. The discharge results were pretty dismal and I was getting rather angry that I got cells that were damaged or old. All three netted the same results so I know my setup was good. However I did not charge all the way to 8.4 volts and hold to c/10. But in order to do that I would need to do a split charge on the module utilizing the center post. So I did a setup for each half with my PowerLab 8 and used my first module that only got 43ah out of it the first time. The charge was at 30 amps and I got 57.3 ah out of one side and 58.3 out of the other side using the power lab. I was even able to graph the volts and AH. It was great. Some places tested modules and only got 58 ah out of new modules. I also heard of some getting 60 ah out. But for used cells these modules did great using the split pack method and charging to 8.4 volts. As you can see on the voltage graph the beginning of the upward curve starts just before 4.2 volts. I could more than likely go to 4.3 volts with no issues. But I will stick with 4.2. More testing coming with different modules. The first graph is a goof up because I set my power lab wrong and it terminated at 3.6 volts. The first two graphs go along with the second two graphs. Combine them. One for voltage and the other for amperage. The last two were the second half of the module and I got it right and only needed two graphs. Volts and Ah. So you can see a real nice charge curve not unlike the LiFePO4 cells. So for the first go around it looks pretty good for these modules. Im a happy camper at this point. This will give my Bus some great range at cruise speeds of 55mph. Might be able to make it to Sac and back without charging. That would be totally cool.