7748Re: Lithium voltage sag
- Dec 11, 2011
> Are you still seeing the same volts as mention in the blog post on the TS pack when under load. I see you only used 48 cells and my plan is for 52. You said you would do 50 next time. Unless I messed up my math the CALB 100 should fit with a 52 count.Hi Mike R.,
> I'll likely never do a 2600 foot climbing grade but I'm impressed that you do it regularly. Do you leave plenty of charge space for a regen down the hill or fill it up at home?
> Mike R
> 97 Force
Yes, the voltages are the same as last year. I used 48 cells because I was concerned about approaching the AMC325 controller's upper voltage limit. I had calculated having 3.8v X 48 cells might be too much for the controller. Since I only charge up to about 3.6v the controller would most likely handle 50 or 52 cells. Yes, 52 cells would easily fit. My front box only has 8 cells in it. I'd rather not get into the last 10% of the controller's rated capacity in an effort to avoid heat and reliability issues. Even in winter the cooling fan on my motor is on during the whole climb to get home (I leave it on for a while after I park in the garage), I'd guess the controller fans are on also.
I rarely charge more than a few Ah's at home. If I've run errands in town before heading up the hill and show 40+ Ah's when I get home I'll charge for an hour or so to bring the cells up a bit before sitting overnight. That's just an old habit (from the original lead pack) of me not wanting to leave the batteries with a low charge overnight. If I head down the hill with more than 25 Ah's showing on the dash meter I can use regen the whole way down instead of brakes. If it's reading less than about 25 Ah's I have to be careful not to regen the cells with too much/too fast.
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