Today my board had shut downs while still at 43-44V (12S5P).
I had to call my wife to come and get me and endure all the snarky comments on the reliability of an esk8
Anyway I opened up the battery when I got home. The series connections were fine but the last P group measured at 3.10V when all the others were at 3.70V.
This explains the shutdowns as I use a discharge BMS (Bestech HCX-D223V1).
I am currently charging that particular P group by itself until it reaches 3.70V as the others and will then continue through the BMS.
Now my question is how/why this happened?
When I measure the output voltage on my BMS I get approx. 1V lower with the e-switch in the off position and the actual battery voltage in the on position.
Is this normal? Shouldn’t I get 0V with the e-switch in the off position?
I don’t think I have a defective cell since I would probable get shut downs in other situations since I tend to push my board really hard from time to time.
My guess is that it is a faulty BMS that somehow leaks current only from the last pack.
What do you guys think?
So far it looks like it is the BMS.
I charged all cells to 3.84V last night.
Checked this morning. All were at 3.84V apart from the 12th P-group which was at 3.80V.
I will check again this afternoon. If it has dropped any further, I will disconnect the balance cable to see if it continues dropping.
It’s not the BMS.
One of the batteries on that 5p group is shorted (or something like that) and bleeds voltage.
I took the p group apart and charged all cells individually. All of them charged at 4.19V last night but one of them measured 4.08V this morning.