It is normal for LiFe cells to plateau during both charge and discharge, they have what is known as a "flat discharge curve". As they approach capacity, yes voltage will go up; wh is a better measure of energy because it takes into account voltage and its change throught the discharge cycle. 120v is way too high for a (assuming a) 28s module, which should have a peak voltage of 102.2. If you don't catch it and you charge your cells to 120v/4.28v a cell, this will degrade their cycle life. You need to buy at $15 (or more) Digital Multimeter to work on your 2k investment, because you picked a tough pack to learn on. :lol:
Charging is a lossy process so you can expect to put in 30%+ more than the pack needs to fill up its 60ah.
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Anyhow, regarding my own modules... My deeply discharged 7s pack completed the slow single-cell charge, consuming 2.5kw, as reported by my kill-a-watt. Its been off for a few hours and voltages are still at 3.67v/cell, so that is a really good sign, I'll let it sit for a few days and hope they hold steady.
I bulk-charged my 28s at 4.2a to 98.4v - 3.55v/cell - and it hoovered down almost 4kw hours. Most of the cells were at 3.58v, but 3 were lower. I marked them specially and put single-cell chargers on them, two came up to 3.67v really fast, the third one is still charging (finger crossed) so at best it was pretty far out of balance. In the worst case, its a lame cell that I kill on a deep discharge. I'd solder a pair of 8ga across the terminals (the buss bar supplies 2 perfect channels) of the bad cells, run 48s instead of 49s (shrug), and carry and extra 3lb of dead weight in a 196lb pack.
Anyhow, I'm also bulk-charging the remaining pair of 7s to 49.7v (3.55v/cell) to see if either of them have a low cell I should be keeping an eye on. Then I'm gonna single-cell charge them, let them sit a few days to look for self discharge, pop them into the camper-bus and take them for a test drive, and see what I can suck out of them.
They broke off a bolt in a terminal in one of my 7s.
The 28s pack was warped in shipping but I fixed it. It was quickly obvious that pushing on the side of the pack would dent the cooling fins, so I gently rolled the pack to its side on a flat surface, lifted one end 6" and dropped it, same on the other end, and the pack was now straight. BTW I noticed the cooling fins on the bottom of the 28s are covered with thermal paste.
-JD