I got lipo questions ya’ll. See this post for reference:
@mynamesmatt this project is awesome.
I have a similar lipo problem. I have 4, 3s packs I want to put in series. Possibly parallel another 4 x 3s pack.
What do you think about the extra lead length incurred by leaving the stock xt90s on the relatively long leads on the 2s packs?
Do these lead lengths add to the ripple voltages that can pop Esc’s? I think the answer is yes, and the solution is more Caps on the mains just before the esc’s. But maybe it’s not a big concern if you have current headroom to play with on your Esc set up?
My other concern is added resistance from long series connections, bc in my case, I don’t trust a BMS. I want to balance charge at 1C (15A) and intermittently keep an eye on IR’s.
Will these longer series connections cause my Balance charger to misread cell voltages on either side of these extra long series connections? My charger can do 12s or 6s x2.
I know these series connections will give me wacky cell IR’s near the long series connection but that’s ok, I’m taking initial reads of new packs and comparing relative changes in the future.
Don’t mean to make this about me, but my use case is real similar. I suspect my average Amp draw is a bit higher (however Metr calculates avg Current) I used to routinely log avg currents of 120-180A over 5-10 mins, in the last year it’s been closer to 80-100A.
I presume higher currents magnify my two concerns above (?)
@moestooge @Battery_Mooch are these concerns for my use case even valid?
Yellow arrows are “long series connections” I refer to above. My tattu 12s (6s X2) packs only have one and it’s 8awg wire with as150s connecting.
My proposed zeee 12s (3s x4) has 3 long connections (10awg 
). I want to cut them really short.
On old packs, I have noticed irregular and inconsistent IR’s on cells directly adjacent to the long series connection. (Cells 6 and 7 if you count up to 12). Maybe dirty or worn out balanced leads 
.
Ripple voltage is a real problem I’m dealing with on the quad unity Esc setup. If I’m riding aggressively, It spits out drv over Volts at the frequency you see tesla cars drive by in socal.