Is this the sign of a bad cell

[Ryang]

I’ve had these 8 cells for about 3 years now. However, as a pack they work great still. I’ve not noticed any issues.

Today, the weather has been crap, so I took the van to charge up on ac power. Fired up all 50amp on the 24/3000/50 multi and had about 400w of solar

So there was about 70amps of charge going in

The BMS starting tripping out, Cell OVP on cell 5. All other cells seemed pretty good.

Here is a screenshot. This 1 cell is flipping from 3.4 to 3.67 very erratically.

I lowered the total
Over to 50 amp and it stayed under the 3.67 limit so was able to charge

What does this mean?

Thanks






I should note, there is slight bloating on some cells

 

[kommando]

Check the connection to the cell, clean in case of any corrosion and remake.

 

[AshleyL]

Definitely sign of loose connection. Fix it quick before there is a serious heating at the loose connection.

 

[Skypower]

Instead of a slower solar charge where current didn’t have much resistance at the busses, it got a good jab at 70 amps and it found the weak link. Probably a loose or corroded buss/terminal. If it got really loose it could damage a terminal, but luckily you we watching.

 

[Ryang]

Makes perfect sense.

To fit the tight space I went from 8 in a row to 4x2, and then the supplied bus bar didn’t fit. So I quickly fabricated one from a piece of copper pipe to get going.

See me like the link from cell 4 to 5 is bad (I.e. the copper pipe.

So I’ll check this first and see what needs to be done.

Thanks for the feedback.

 

[AshleyL]

Makes perfect sense.

To fit the tight space I went from 8 in a row to 4x2, and then the supplied bus bar didn’t fit. So I quickly fabricated one from a piece of copper pipe to get going.

See me like the link from cell 4 to 5 is bad (I.e. the copper pipe.

So I’ll check this first and see what needs to be done.

Thanks for the feedback.

Wait.....tinned copper or pure copper?
If it is pure copper......do you apply any anti-oxidation stuff on it?
Galvanic corrosion is nothing to laugh at.......