Have you had a fuse wire blow on any of your cells ?

jestronix

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Nov 7, 2017
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I'm really interesting to hear from some of youwho have had their powerwall running for a year or two, to see if anyone has had a cell fuse pop on its own. With 1000s of cells in daily use, it would be great to see some instances that have saved people's packs.

I've tested some 8a house fuse wire and of course it pops on shorting out, but I'm using some glass axial 4amp fuses to ensure they pop if down low. But why?

I presume there are a fewways a cell can fail, thermal runaway is one that fuses will not save ? The other is a cell shorting out completely meaning a 20 to 40 amp fuse will do the same as my 4 amp fuse. Correct ? Average joe I think is using 1 amp fuses, he mentions he doesn't want a bad cell taking down the rest of the pack. is there a situation where you get a semi shorted cell that drains the rest of the pack ? I presume this is why he is using 1 amp fuses. But I can see it would still drain the pack if it draw less than one amp.

Anyone keen to know if anyone has had a fuse blow and if it was a dead short or semi failed ?
 

Korishan

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Pete and AverageJoe had fuses pop on their own. And they both have a video of replacing the problem cells
 

daromer

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I have not seen anyone and it have been running for a year. But I have not checked it since like 4 months or so.
its easy to replace though.
 

jdeadman

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I have in my lawn mower pack but I was pulling too many amps and one blew and then that increased load on the rest of the cells blew the rest. but this was just an assumption as I didn't see it happen but one cell was scorched more than the others so I would assume it got hot for a bit before it blew. the rest looked great
 

jestronix

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Looks like there must have been a few in the 1000s and 1000s of cells out there, certainly adds peace of mind though. I guess the next question is a 4 amp vs 15 amp better than the other. I take it lower is better as u can grab a cell early in its decay and stop a slow overheat. However even half an amp can push a cell seriously hot.

It makes me think batrium could have a number of stickon thermo sensors through out the pack, maybe 4 or 8 that connect to the longmon and report back somehow, I thought if battery packs were sealed and air was pushed through the pack, a sensor on the exhaust side could monitor heat and shut down when things are above a threshold, but more moving parts etc.
 

Korishan

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@jestronix: The fuse isn't designed to protect the cell from being charged at a slow rate. It's there to protect it from rapid charging from the other cells in parallel with it (if it happens). So, even 5 other cells dumping 1A (5A total) into it should be enough to blow the fuse. A 4A fuse will take a little bit of time to pop; maybe a few minutes. I wouldn't put a 15A fuse wire on the cell level. Maybe pack level if the pack was small enough.
 

hbpowerwall

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i've found 5 i can say for sure have blown due to bad cells.
 

wimpie007

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What's the best rating for these glass fuses?
I found some 2A rated ones, which sounds enough for a powerwall...?
 
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