Is my battery messed up, or are my settings messed up? Possible dead P group?

How-Tos & Esk8 mechanics Esk8 Mechanics
#1

Hey everyone, I’m trying to diagnose some weird stuff I’m noticing with my build as of late. Here’s some quick specs:

-12s4p 30Q
-Flipsky 6.6 dual
-Dual flipsky 6354 190kv motors
-16:60 gear ratio

VESC settings:
Motor current max: 65A
Motor regen max: -50A
Battery current max: 25A
Battery max regen: -16A

Cutoff settings (this used to be cutoff start at 40ish volts and cutoff end at 36V, adjusted the settings in hopes of being softer on the battery):
Cutoff start: 42A
Cutoff end: 37.5A

I put my AT tires (dickyho solid rubber 145mm tires, not honeycomb) on because I’m waiting for new belts to arrive for my street setup. I’ve noticed that the board’s performance seems to have declined considerably recently. Recently, when the charger shuts off, the battery’s voltage is usually no higher than 49v. Usually it would be 50v+ afterwards. I’ve tested this with both of my chargers and they both do the same thing, so I know it’s not a charger issue. So that’s a possible thing.

The board’s performance is quite degraded after only about 6 miles of riding, but from what I remember, when I had my AT setup on before I could usually get 12+ miles before performance started declining.

I’m wondering if my settings are inefficient somehow, or if my battery is messed up. I used to have my motor max at roughly 50A instead of 65A, if that makes a difference. A big question I’m wondering is how much voltage sag during acceleration is acceptable? I have a bluetooth module on my VESC so I get live telemetry, and on xmatic I saw that during acceleration (had already ridden for a lil bit) the voltage dropped from ~47V to ~42V. Haven’t kept much of an eye on this before, and obviously I know that the voltage dips when accelerating, just wondering if this amount is normal for this pack.

I don’t think I’ve put more than like 400 miles max on this board. Are these possibly symptoms of a dead P group, or some other issue? I had my pack built by Psychotiller, in the event that my pack is messed up does anyone know if he services batteries (I’d assume he does)? Or am I worrying about nothing here?

Apologies for any stupid questions, this is my first build and I’ve been learning some stuff as I go. Any help appreciated.

#2

Sounds like you have P group that arent balanced. If you can access the connections of each series groups, check the voltage of each group. If they arent balanced you’ll have to individually charge each group to a balanced state.

You could also replace current bms with a smart bms and static balance the pack for a week or two. All you need is them to be .05 difference and the bms can charge balance them completely balanced.

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#3

Gotcha, thanks so much for the help. Unfortunately, I don’t have easy access to the connections as the battery is wrapped and I don’t much want to remove the wrap. Any idea if @Psychotiller would do this for me (either for a fee or for free, I’m not sure if psychotiller has any kinda warranty program for his packs or anything) if I sent him the pack, or if anyone else on the forum would be willing to do it?

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#4

I am sorry he is busy 3d printing wheels much better than me,

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#5

I thought psycho is not active anymore?
And I read somewhere his batts are questionable…

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#6

Chargers usually turn off below a certain current. BMS only draw a small current while balancing. Maybe the charger turns off before the BMS can balance. You could try to use a lab bench power supply or DCDC converter set to 50,4v and wait some days and see if the voltage rises slowly.

#7

If both of those are true then I’m probably a little fucked. I don’t have the tools to work on the battery, and I don’t much want to take the wrap off to check voltages. I was honestly kinda hoping psycho would service it/check it for free, both because I currently have no money to speak of, and considering I really haven’t put too many cycles on this battery and it’s only about a year old or so. Do you know anyone on the forums who services batteries?

#8

You could ask here. There are many people here that service batteries.

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#9

Lol, oh, I know my settings are ridiculous. I do commend your helpfulness.

:call_me_hand:

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