Shunt snapped and caused a fire🔥

[nezjnr]

Got a call Sunday from the wife about smoke coming from the garage and fire trucks were already on the way.

After they had there fun spraying many cans all over the garage I got to have a look inside.

I have 5 rows of shelves with 2 shelves for in each with a battery and then busbar along the top for interconnecting everything.

I had each battery on a 300a shunt, looks like my failure was the shunt actually snapped right in half, then probably made contact with the wood underneath/metal frame and looks like shelf collapsed onto the bottom battery and probably 10 cells let off the smoke/burned .

Definitely should have had a fire alarm in the garage hooked in with the house.
And should have mounted the back of the shunts on isolators.

I tried braking the other shunts but couldn't get any to give think it was just a defective one.

 

[time2roll]

Was the shunt mounted to something solid? A before picture would be interesting.
Sorry for the troubles.

 

[OffGridForGood]

Wow what a mess,
I don't think I have ever read of a fire caused by a shunt, what make and model ?

 

[42OhmsPA]

Wow that looks miserable, fortunately it wasn't worse.

Are you sure the shunt was the root cause? Is it possible one of the particle board shelves collapsed causing a dead short and the shunt to fail?
The shunt was on the negative, correct?

 

[SupraSPL]

That's was I was wondering, shelf collapse break the shunt?

 

[nezjnr]

It's really hard to determine because the fire fighters sprayed and hosed it deforming a lot of the plastics and wood.

But the shunt was on the negative, going to a breaker, it had no strain on it so the battery dropping wouldn't made the shunt snapped like that.

I think it was poor design on my part really should have had an isolated under the non busbar side for support but also the metal mustn't have been great because it's sheared it's self inflicted half.

 

[nezjnr]

I just got power restored hoping my Home assistant caught the cell voltages and current flow at the time, wil add if I can get.

 

[nezjnr]

Shunt and Monitor was one of these.

https://a.aliexpress.com/_m0YM7ro

I got the 300a shunts, highest current was only 60a

 

[seneysolar]

Holy crap!!!!!
Do you have "before" pictures???

 

[seneysolar]

I have a feeling with that style shelving, with the typical partical board inserts they come with, one of the shelves finally gave out and dropped some batteries. They do not hold heavy objects very long...

 

[rhino]

Were those shelves the ones you get at menards/Home Depot that are particle board and the cells were on them?

 

[OffGridForGood]

Shunt and Monitor was one of these.

https://a.aliexpress.com/_m0YM7ro

I got the 300a shunts, highest current was only 60a

looks like the shunt is 50A max under constant load.

 

[rhino]

looks like the shunt is 50A max under constant load.

I got the impression they must have a 300A version since that 50A one doesn't look like what is shown in the burnt pictures.

In any case I would not trust a critical piece of your power system that all power in your system goes through to some not well known Chinese brand.

 

[rhino]

Should also say we are sorry for your loss and thankful it just appears to be that area of the home/garage that was damaged. Thank you for sharing so others may be able to learn.

 

[nezjnr]

looks like the shunt is 50A max under constant load.

I bought a different model, but it was this model/design

 

[nezjnr]

Holy crap!!!!!
Do you have "before" pictures???

Not really before pictures but from the other end.

I'll have a look later for before pictures.

 

[nezjnr]

I have a feeling with that style shelving, with the typical partical board inserts they come with, one of the shelves finally gave out and dropped some batteries. They do not hold heavy objects very long...

These sit on a lip for support and were rated for the weight of the batteries...

 

[nezjnr]

Should also say we are sorry for your loss and thankful it just appears to be that area of the home/garage that was damaged. Thank you for sharing so others may be able to learn.

Yeah, thankfully it's just some money and time and a lot of stress.

But wife is fine, cats are safe garage plater just needs a little bit of touching up and paint.

Hopefully it helps someone.

 

[Brucey]

Not really before pictures but from the other end.

I'll have a look later for before pictures.

That shunt doesn't look like it has an isolation base. A Victron for example:

 

[rhino]

Thanks for the extra pictures.. couple questions, why are there alligator clips on all those cells? also is there some insulation between the cells?

In any event even if those shelves are rated for the weight you had on them I would never trust particle board for something like that. It is not a stable "wood" and can easily warp especially when exposed to moisture. If it warped at all it would cause the collapse of the shelf.