House burned down

[robbob2112]

AIC rating can vary with voltage.

Interrupt Capacity

10000A @ 14V DC 5000A @ 32V DC 2000A @ 58V DC

MRBF Terminal Fuse - 30A - Blue Sea Systems

Space-saving ignition protected fuse for 30 to 300 Amp loads. Must use with Terminal Fuse Block.

www.bluesea.com

Agreed, but a 600v fuse used on a line with 500vdc and 30amps shouldn't have a problem so long as the 30 amps is not exceeded.

But, the resistance of fuses does vary by the amp rating, which means heat output varies by amp rating.

From my testing with the class T and Chint fuses the higher the amp rating the lower the internal resistance.

From looking back earlier in this thread where I posted a picture of a bunch of fuses side by side, the larger the higher the voltage rating the larger the fuse. The Class T in the picture are rated 125vdc and 160vdc. The larger is physicaly bigger. The Chint have a way higher voltage rating and much larger. But their internal resistace is higher so more heat loss. But they sit in the holder in open air to disipate the heat.

See

House burned down

Possible solution: BACK UP. This guy is FUSED 🤣 1 on each battery, 1 300amp anl and 1 T class. 🤣 fused Probably had a fire - bad experience Link for the contactor? The MRBF is probably OK, but I get them from Mouser for eaton brand.

diysolarforum.com

Now, all that said - our friend @dianea had a fuse mounted to a DIN rail and looked like screwed to a sheetrock wall verse inside an enclosure and she was kind enough to post a picture of it as a warning - so I was asking for any details she could provide about the fuse itself. As in type/voltage/amps from which we can see why it did what it did.

I suspect from the picture there was a short somplace or more likely the fuse was being run near its amp limits and it heated up like the filament in an old light bulb. and burned the wall and melted whatever the casing it. That looks like a fuse holder that has a flip out door and you put a fuse inside it.


P.S. @dianea - if you have more pictures I would like to see one from farther way showing all the damage, looks like the wire on the right had a melted sheath.

 

[AntronX]

The voltage rating is where it won't arc over/through the insulation into anything else.

The voltage rating is so that it can safely break an arc and not explode/catch fire and cause this forum thread.

 

[yabert]

From dianea: ''It was a set of AC 600 volt fuses on a 500 volt DC feed from the panels''
AC voltage is way easier to break than DC voltage.
It's why some class T fuse have 200ka AC interrupting rating, but only 20ka DC rating.

 

[robbob2112]

From dianea: ''It was a set of AC 600 volt fuses on a 500 volt DC feed from the panels''
AC voltage is way easier to break than DC voltage.
It's why some class T fuse have 200ka AC interrupting rating, but only 20ka DC rating.

I missed the AC part of that, but most AC fuses are also rated as DC fuses at lower volts. And it makes a difference on fuse type of how much lower that rating is.

I do see your point now - valid - so she was using the incorrect rated fuse in that because her string voltage was so much higher that.

I think she was using something like this - (random off amazon) - 600vac might be a 380vdc fuse....

 

[dianea]

What sort of fuse was it? I ask because a 600v fuse on a 500v feed shouldn't matter at all. With fuses it is all about the current running through it. Most fuses are way over the voltage used. The voltage limitation is all about the insulation.

The vaporized fuses used to be Littlefuse CCMR 15, rated "600 VAC or less " no DC rating at all. This was in my shop and happened during destructive FAFO testing of improper parts. The fuses were installed in a surplus three phase Allen Bradley 1492-FB3C30 fuse holder with indicators. It's indicators weren't needed this time to let me know the fuses had failed. This experiment may suggest using wrong fuses for the wrong application with no enclosure might cause infinite more harm than any good. And a reminder that rated enclosures are a good idea...

 

[gotbeans]

So one thing I notice in all the pictures of the battery cells. It appears there is no separator between the individual cells? Seems like I remember reading that if they are under any sort of compression or even straight confinement sonthe expansion is limited there should be some sort of separator used?

I know in one of the threads the OP had one or more vented cells. Could that be a cause? Cell vent which off-gases hydrogen among other things. Shorted cell generates heat and with the hydrogen confined it just needs a spark. If the high current causes the fuse to blow but arc keeps it alive it will melt the casing and catch fire. One reason I don't like the ANN, ANL, and all their cousins.

Where do you get they off gas hydrogen from?
I know lead acid off gas plenty

All I see is this which doesn't directly say that

How safe are lithium iron phosphate batteries?

Researchers in the United Kingdom have analyzed lithium-ion battery thermal runaway off-gas and have found that nickel manganese cobalt (NMC) batteries generate larger specific off-gas volumes, while lithium iron phosphate (LFP) batteries are a greater flammability hazard and show greater...

www.pv-magazine.com

So uh where are you supposed to store propane tanks?
<eyes the 20lb tank in the garage>

make concrete boxes for it with hardie backer board
I put my batteries inside a big box as well
Probably need a vent outside for the propane tanks? but it'd protect them from other stuff getting at them
We have always had big tanks that are like 30ft away from the house sit outside, never inside

 

[robbob2112]

You are looking at Lipo batteries. When the electrolyte breaks down from a shorted or overcharged cell...i.e high temp vent


1. **Carbon Dioxide (CO2)** - From the breakdown of organic carbonate solvents.
2. **Carbon Monoxide (CO)** - From incomplete combustion or decomposition of the electrolyte.
3. **Hydrogen (H2)** - Generated from the decomposition of organic materials and electrolytes under extreme heat.
4. **Phosphorus Pentafluoride (PF5)** - Produced from the decomposition of LiPF6, a common lithium salt in the electrolyte.
5. **Phosphorus Oxyfluoride (POF3)** - Another decomposition product from LiPF6.
6. **Hydrogen Fluoride (HF)** - Forms when PF5 and POF3 react with moisture; highly corrosive.
7. **Lower Alkanes and Alkenes (e.g., methane, ethane)** - These can form through the breakdown of organic solvents under severe thermal conditions.