Voltage going down while NOT in use

[Joey11]

drop from what voltage to 56V. have you disconnected bms and controller as we suggested to see if that would change??
you need to sort out one possible error source after the other.
i din't know why you don't do so and just wait ....
56V is dead empty for 20s lipo. voltage will go down to zero within hours now. you need to charge to 3.8V per cell immediately and start testing as we told you.

Dropped from 76v to 56v plug it off the controller, and connected it to charge via bms in order so save them..
So I would wait until it will get to 77( so after sag it will get to 76 (3.8 per cell))
And if voltage won't drop, controller is the issue and if it will, bms is the problem?

 

[Ykick]

Process of elimination my friend.

Begin with nothing connected to the cells/pack. Note each cell group voltage and let it sit 3-5 days. If you have significant drop in voltage over that period = bad cells.

If passing the leaker test, do the same test with BMS connected. Followed by further testing with the controller connected ignition OFF.

By that point you should have enough data to compare and determine what may be responsible for your loss of charge.

 

[Joey11]

Ok, in what order should i disconnect the BMS. the P- is already disconnected, Charger - can be left connected, correct? so what next, cells balance connector or B-

 

[Ykick]

I don't believe the order really makes much difference but I would pull the multi-pin cell channel connector followed by B-. Main thing is nothing should be left connected to the cells/pack.

 

[dogman dan]

TOLD YOU TO PUT IT ON A CHARGER If the charger is connected all the time, it's sucking your power when it's not plugged into the AC. Your pack is warming the charger.

The drain, whatever it is, took the cells off the cliff. Below 3.5v per cell, they drop fast!

Furthermore, have an easy way to do a complete disconnect. This is why electric cars use an expensive contactor. All you need is a plug you can reach.

How reliable is this voltmeter you are going by? Was your pack really at 70v when you ignored the need to recharge it?