diy solar

diy solar

Shunt snapped and caused a fire🔥

Did the fire department, or city have any issues over the DIY battery bank? Looks to be a large storage bank. In my city likely be getting a letter in the mail with a fine for an unpermitted DIY lithium battery bank.

Nice to see a diagram of the setup maybe the OP has one.
 
It's pretty epic.

In my experience those cables with the insulation burned off that are green are ones that got super hot due to shorting.

That must have a very special smell to it.

Halon, burned plastic, lipo4 juice, burnt particle board and defeat.
 
One thing that I noticed is the steel frame of the shelving unit held up. But the wood shelves did not.
Costco sells two types of these industrial shelving units. One with particle board shelves and one with steel shelves. The last time I looked at these at my local Costco, the steel shelves type did not cost much more than the wood one.

When you look at rack mount batteries (EG4, Ruixu, etc.) they all use a fully metal server rack. No wood or plastic in them at all, except for the wiring channels. And the batteries themselves are enclosed in a metal case. There's a good reason for that. The OP's unfortunate experience is a prime example of that.

I'm really sorry that this happened to the OP. Thank you for sharing this with the forum so we can all learn from this.
 
OffGridForGood said:
Not attacking the OP, just want to point out some things to be warry of,
For, Guests, others learning - review the pics-

...

5. we see all-thread rods, with thick plywood ends. we don't see any cushion material anywhere to allow the cells to expand, we don't see any springs at either end of the all-thread rods to allow the cells to expand. Depending on which cells these are, we need to allow up to 1mm per cell for a full charge expansion. Without any room, the cells can be over-compressed and vent. The cells could have been set in the rods at full 100% charge, not become over-compressed. but seems unlikely. Better to have no compression rather than over-compression. Maybe the fire burnt away some springs and we don't see them now.
Click to expand...
I agree with your points 1-4 but not with 5. The EV packs these cells are designed to go into use rigid compression with no expansion mechanism. They won't vent just from being held regular fully charged expansion pressure. Preventing that regular expansion seems to be precisely the intention of EV pack compression.
 
Skypower said:
Failure analysis is very difficult when many points of failure no longer exist. A video or actually witnessing the event would be more definitive. Everything is just a guess. A photoelectric plus ionic smoke detector could give you early warning and IF someone was home, perhaps it could have been observed at a smoldering stage or shut down.
Click to expand...

There are also WiFi connected smoke detectors. I know that Google Nest makes one. You get notifications on your phone if smoke or CO2 is detected. There's no subscription fee for the Google unit. I do have a standard smoke detector in my garage. Now I'm thinking I should get a WiFi connected smoke detector.
 
nezjnr said:
These sit on a lip for support and were rated for the weight of the batteries...
Click to expand...

When looking at the picture from the above #17 posting, it seems that the particle board under the battery
was holding the weight only on its edges and get warp and could not handle the weight of the battery.

A single 280 AH LiFePO4 prismatic cell weight about 5.5 kg or 12 lbs.
So a 48V battery with 16 cells will weight about 88 kg or 195 lbs.

Shunt snapped and caused a fire #17 01 .jpg

I recently build a rolling cart shelf to hold and carry my batteries,
and I was worried about having a single piece of particle board could handle such weight
even if the manufacturer (The Muscle Rack) was advertising 800 lbs. per shelf.
Maybe the 18-gauge steel frame would, but not the particle board shelves.


So I started looking in another direction, and found some racks with wire shelves:
Those shelves (Husky Rack and Wire) (Gladiator) (DeWalt) can be found in majors stores,
like Home Depot, Costco, Wal-Mart..

I bought a 4-Tier rack (36 in. W x 72 in. H x 18 in. D) but I used only half of the height
to make a 3-Tier rolling cart (36 in. W x 36 in. H x 18 in. D) that I bolted on top of a
platform with 5" swivel casters, so I can easily move around two 48V 16 Cells batteries.

Each battery has its own T-Fuse, Nader 200A Circuit Breaker with Enclosure, and Anderson connector.
In case of a problem, the batteries could be moved quickly outside, or if they are installed outside of a house,
they could be moved back inside for doing some temporary service work.

wire shelves 01.jpgwire shelves 03 .jpg
 
Last edited:
hwy17 said:
The strained shunt snapping theory doesn't satisfy me. There's three pieces of metal that would have to snap together or one by one.

Not that I have a super clear understanding of the system, OP knows it best, but my gut reaction is the shunt melted from a short.
Click to expand...

I wonder if the OP may have saved, on the Cloud, some recording of the battery charging status and consumption load
to elaborate about the melting overloaded shunt theory?
 
I quite like the look of those shelves with the mesh, stick some cement board on the top, it's insulating and non-flammable and at least that part of the issue is solved. I might be tempted to beef-up the cross members but I'm a belt-and-braces (US - suspenders) man.

Our packs live on DIY shelves of 1"square x 1.5mm thickness steel tube, welded together then bolted to 2"x 1" square uprights with 2 x M8 bolts at each corner. I can stand on the centre of the shelf without it moving noticeably and I'm not exactly slim and silth-like. (OK I'm a fat b'stard).

Cement board shelf surface and walls, nothing flammable except the wiring and cells in there.
 
再生可能 エネルギー said:
When looking at the picture from the above #17 posting, it seems that the particle board under the battery
was holding the weight only on its edges and get warp and could not handle the weight of the battery.

A single 280 AH LiFePO4 prismatic cell weight about 5.5 kg or 12 lbs.
So a 48V battery with 16 cells will weight about 88 kg or 195 lbs.

View attachment 197741

I recently build a rolling cart shelf to hold and carry my batteries,
and I was worried about having a single piece of particle board could handle such weight
even if the manufacturer (The Muscle Rack) was advertising 800 lbs. per shelf.
Maybe the 18-gauge steel frame would, but not the particle board shelves.


So I started looking in another direction, and found some racks with wire shelves:
Those shelves (Husky Rack and Wire) (Gladiator) (DeWalt) can be found in majors stores,
like Home Depot, Costco, Wal-Mart..

I bought a 4-Tier rack (36 in. W x 72 in. H x 18 in. D) but I used only half of the height
to make a 3-Tier rolling cart (36 in. W x 36 in. H x 18 in. D) that I bolted on top of a
platform with 5" swivel casters, so I can easily move around two 48V 16 Cells batteries.

Each battery has its own T-Fuse, Nader 200A Circuit Breaker with Enclosure, and Anderson connector.
In case of a problem, the batteries could be moved quickly outside, or if they are installed outside of a house,
they could be moved back inside for doing some temporary service work.

View attachment 197746View attachment 197747
Click to expand...


Anderson connectors are great in most situations, but unless they are connected and disconnected ones in a while they can have slight increases in resistance. At high amp flow that can cause them to heat.
 
Those pictures are scary! Atleast it was only the garage and not the living quarters; also props to the wife for noticing the smoke when she did!

If you do decide to rebuild the system the same way or have blueprints of your old one, I would revise those plans and scope the entire build to see if there would be any faults and make some changes/modifications. A few builders have told me even the best systems should have room for tweaks in case of the 'what-if' should ever happen. As far as that shunt goes, avoid them. We had a 50A model of that same one and we noticed a burning odour around 30A. I doubt it had passed many (or any) safety testing before it was released on the market.

I surely hope you guys are doing well though (and the cats, thank goodness they're safe too) and look forward to seeing the next build!
 
highwaypirate said:
Those pictures are scary! Atleast it was only the garage and not the living quarters; also props to the wife for noticing the smoke when she did!

If you do decide to rebuild the system the same way or have blueprints of your old one, I would revise those plans and scope the entire build to see if there would be any faults and make some changes/modifications. A few builders have told me even the best systems should have room for tweaks in case of the 'what-if' should ever happen. As far as that shunt goes, avoid them. We had a 50A model of that same one and we noticed a burning odour around 30A. I doubt it had passed many (or any) safety testing before it was released on the market.
Click to expand...
Most shunts are only good to 66% of there rating for continuous use. In you case 33 amps..... But if it is a cheap shunt........
highwaypirate said:
I surely hope you guys are doing well though (and the cats, thank goodness they're safe too) and look forward to seeing the next build!
Click to expand...
 
I have the exact same rack as the op, however its particleboard was replaced with 3/4” ply and the depth narrowed for more room ( cut rails, some rivets replaced with bolts). It was then bolted to the studs in the wall. The thing is rock solid and have stood on it many times for over head lights and smoke detector install. I hate particleboard as it seems to sag under its own weight with time and humidity. Never ended up using them for shelving but for spray paint backstop.
IMG_0773.jpeg
 
The other thing with particle board once it gets wet it's completely useless if anything leaked out of the cells and soaked into the shelves...
 
grizzzman said:
Most shunts are only good to 66% of there rating for continuous use. In you case 33 amps..... But if it is a cheap shunt........
Click to expand...

I started out with what looks like the same shunt as the OP was using. I returned it in favor of the victron shunt. The build quality wasn't good, the hardware was from the reject bin at the factory (threads not fully formed in the nut or bolt) and measuring with a volt meter + the reading from the invert itself the shunt was about 20% off.
 
I doubt this would have helped here, but I have been using a (non toxic) product that soaks into wood and creates an intumescent class A fire barrier. Sprayed all of my I joists, interior framing (exterior has closed cell foam around them), any plywood I hang, and will spray my newer battery boxes too.
 
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