Battery issue.

I have a 52v 17.5 ah pack from Luna cycle. I use this for my 3Kw Cyclone kit. It just quit working. The battery is only showing 3.6v at the discharge. Nothing on the battery voltage indicator. Now when I plug it in to the charger I get 56.6 v , indicator works fine. Is my BMS fried? Thanks.

Nopedalportland said:

I have a 52v 17.5 ah pack from Luna cycle. I use this for my 3Kw Cyclone kit. It just quit working. The battery is only showing 3.6v at the discharge. Nothing on the battery voltage indicator. Now when I plug it in to the charger I get 56.6 v , indicator works fine. Is my BMS fried? Thanks.

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Or the BMS is working correctly and the battery itself is fried.

The 3.6v means that the BMS has switched off discharge. you have to open up the BMS and measure the cell voltages on the multi-pin connector to the BMS to find out why.

IMO,, 3kw is just too harsh for that battery. Oh sure, its technically able to do it, but you just proved it hates that. Its possible, you can simply balance the battery manually and be ok for a time, but long term, you are beating it I think.

For now though, look into how out of balance it is, and try to get it back to all charged and balanced. It could be that the pack is just so out of balance the bms can't keep up. Not fried, just would take a month or so to get there at the rate the bms can balance the pack.

The bad news, I think it will just get driven out of balance again. And, it might already have enough killed cells to be a brick now.

Yep, it is very easy to damage LiCo cells. Discharge C rate abuse and low voltage discharge are very hard on them, but on the other side they can stand pretty good charging faster and higher than spec. The best indicators are heat and disbalance: If your battery gets hot or your cells are often off balance, you are pulling too much on it and going for short life expectation.

Contact the vendor. Get technical support from them.

Did you try and contact Luna Cycle? Is there a warranty?

you have probably killed the fets or melted a trace in the bms you can avoid this in the future by taking power wires direct from the battery and useing your new bms to switch a relay insted

Which Luna 17.5ah pack ? Which cells. Important.