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diy solar

BMS fried?

BroomJM

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Apr 7, 2021
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I was installing a DIY battery into my boat and had two wires touch that shouldn't have. Lots of sparks for just a second or two.
The battery cells still read full voltage, at the cell and pack level. From positive of the battery to B- on the BMS, I get 26 volts (24v nominal battery). From the positive of the battery to the P-, I get 5.6 volts. I'm guessing the BMS is damaged internally, so it can no longer pass through the current from the battery to the load?
 
UPDATE: Apparently the BMS did its job and projected the battery AND itself from any damage. I waited about an hour, which is how long it took to stop being mad at myself for doing something so stupid, and when I checked the P- and actual SB50 connector, they were both showing 26 volts, just like the battery to B- was showing. So, it looks like everything is OK.
 
Yeah, been there, done that, got the t-shirt.

For "next time", most BMSs will recover from protection mode if you (briefly) short B- to P- or charge the pack with a "dumb" charger (or just put another battery of the same voltage in parallel).
 
Yeah, been there, done that, got the t-shirt.

For "next time", most BMSs will recover from protection mode if you (briefly) short B- to P- or charge the pack with a "dumb" charger (or just put another battery of the same voltage in parallel).
That is good to know, and fervently hope there will be no next time! :)
 
Yeah, been there, done that, got the t-shirt.

For "next time", most BMSs will recover from protection mode if you (briefly) short B- to P- or charge the pack with a "dumb" charger (or just put another battery of the same voltage in parallel).

In my experience, I have a 2p bank and when one of the BMSes goes into sleep, disconnecting them from being in parallel wakes it up.

I'm thinking of getting the Victron charger still, though.
 
I would still watch it carefully for a couple of cycles. I had a DALY 48 volt version that was damaged in a lightening strike and it appeared fine but I found out that even though it seemed fine in reality it would not disconnect at LVD or HVD. It seemed fine with no errors read voltages and showed all charge/discharge cycles but was actually toast…. Trust but verify.
 
I would still watch it carefully for a couple of cycles. I had a DALY 48 volt version that was damaged in a lightening strike and it appeared fine but I found out that even though it seemed fine in reality it would not disconnect at LVD or HVD. It seemed fine with no errors read voltages and showed all charge/discharge cycles but was actually toast…. Trust but verify.
That's a very good point. I'll check it out today and make sure it does what it's supposed to do.
 
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