LiFePO4 prismatic cell short circuit current and main circuit protection

[pablo fiasco]

Send me some cells and I'll do it. I'm more worried about it happening when I'm not there to put out the fire.

I am paying attention to your adventures and advice. I've been waiting for all the bits and pieces to come arrive before starting to cut and crimp. I hope to insulate every bit of the system, + & -, so that I can pretty much empty my tool box onto it if the mood strikes me.

 

[ArthurEld]

I am paying attention to your adventures and advice. I've been waiting for all the bits and pieces to come arrive before starting to cut and crimp. I hope to insulate every bit of the system, + & -, so that I can pretty much empty my tool box onto it if the mood strikes me.

Sounds good. Also cover all possible shorting connections with a piece of thin plywood or cardboard or plexiglass.
Then you don't have to worry about something falling on it. And don't let kids play near the battery.
There are everyday occurrences that could cause something metallic to bounce or fall on top of the battery causing a short when you aren't paying attention. So, it's not just insulating your tools that you need to worry about.

My short was caused by a tool and it is the most likely way but there are other ways. Even a small short could get a fire going if you don't notice it.

 

[chops728]

I was building some buss bars ---so I would make one and check to see if they aligned up -- so stupid me had a short 13mm wrench and I put my hand under it to make sure it didn't touch the other terminals --I forgot all about my wedding ring -- I shorted across one CALB cell for one spark (a blink of my eye ) I moved my hand away quick -- My wedding band was sort of glowing --Burnt the CRAP out of my finger--Needless to say --All my wrenches etc are wrapped with tape now

 

[ArthurEld]

I bet people have lost their finger from that.

 

[pablo fiasco]

Sounds good. Also cover all possible shorting connections with a piece of thin plywood or cardboard or plexiglass.
Then you don't have to worry about something falling on it. And don't let kids play near the battery.
There are everyday occurrences that could cause something metallic to bounce or fall on top of the battery causing a short when you aren't paying attention. So, it's not just insulating your tools that you need to worry about.

My short was caused by a tool and it is the most likely way but there are other ways. Even a small short could get a fire going if you don't notice it.

There's something called 'thermal plastic beads' I've had in my toy box for years. They are non-conductive so I'm thinking just to glom a dollop of it on any part of the system that isn't otherwise insulated. I suppose there could be a heat issue if there's a bad connection or an under size wire. Stuff gets malleable at 150F. I seem to remember getting to burn once upon a time. Maybe not a good idea?

 

[ArthurEld]

The thermal plastic beads sound amusing. Hopefully they are easy to remove and not flammable.

I plan to put heat shrink on my busbars and eventually coming up with something that can easily cover the terminals.
My distribution busbars and fuses are covered. My BMS will be away from terminals and the BMS connections will be covered.

 

[HRTKD]

Send me some cells and I'll do it. I'm more worried about it happening when I'm not there to put out the fire.

Stop storing wrenches in the battery compartment and you'll be OK.

 

[ArthurEld]

Stop storing wrenches in the battery compartment and you'll be OK.

I don't even hold an uninsulated tool over my battery. The most dangerous thing I hold over my battery is busbars.

 

[pablo fiasco]

The thermal plastic beads sound amusing. Hopefully they are easy to remove and not flammable.

I plan to put heat shrink on my busbars and eventually coming up with something that can easily cover the terminals.
My distribution busbars and fuses are covered. My BMS will be away from terminals and the BMS connections will be covered.

Okay, so I guess I can scrap that idea. Just went out and put a flame to it and it does in fact support combustion.

 

[ArthurEld]

Sounds good. Also cover all possible shorting connections with a piece of thin plywood or cardboard or plexiglass.
Then you don't have to worry about something falling on it. And don't let kids play near the battery.
There are everyday occurrences that could cause something metallic to bounce or fall on top of the battery causing a short when you aren't paying attention. So, it's not just insulating your tools that you need to worry about.

My short was caused by a tool and it is the most likely way but there are other ways. Even a small short could get a fire going if you don't notice it.

Don't put plywood or cardboard over the batteries. I have to go out and remove mine.

Fire!! Never cover LiFePO4 with wood!!!

New adventure.. I went inside the battery room. As the exhaust fans where working, and they are temp based, I felt OK to close the door. I used wood (MDF) to cover the cells and sit on top, and to prevent accident if something falls 2 left over pieces, 10mm, but strong enough to sit on, as...

diysolarforum.com

 

[jwelter99]

Don't put plywood or cardboard over the batteries. I have to go out and remove mine.

Better - don't let anything, top cover included, rest on the studs/busbars/wiring. Ensure your top cover is mechanically fastened to prevent contact and keep clearance.

 

[John Frum]

Better - don't let anything, top cover included, rest on the studs/busbars/wiring. Ensure your top cover is mechanically fastened to prevent contact and keep clearance.

I guess this is a bad idea then.

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Will have to figure out something better.

 

[ArthurEld]

I've been thinking about ways to cover my terminals for a long time.
And I still haven't settled on a solution.
Clear would be best for me but plastics add fuel to the fire.
So, maybe glass?

 

[carbon60]

I've been thinking about ways to cover my terminals for a long time.
And I still haven't settled on a solution.
Clear would be best for me but plastics add fuel to the fire.
So, maybe glass?

Some kind of FRP? (Not clear.)

 

[ArthurEld]

Some kind of FRP? (Not clear.)

It doesn't absolutely have to be clear.
But I think even FRP would be nasty in a direct fire.

There are many fire resistant materials but I would prefer something that won't burn or give off toxic fumes.

 

[jwelter99]

It doesn't absolutely have to be clear.
But I think even FRP would be nasty in a direct fire.

There are many fire resistant materials but I would prefer something that won't burn or give off toxic fumes.

I think Lexan will not burn and probably the best choice for clear besides some sort of shatter resistant glass?

 

[ArthurEld]

I think Lexan will not burn and probably the best choice for clear besides some sort of shatter resistant glass?

There's probably different versions but this one says it will melt and burn - https://www.lexanpolycarbonate.com/multiwall_polycarbonate_technical_information.html

 

[John Frum]

There's probably different versions but this one says it will melt and burn - https://www.lexanpolycarbonate.com/multiwall_polycarbonate_technical_information.html

What are drop in replacement casings made of?

 

[ArthurEld]

What are drop in replacement casings made of?

I'm not sure what that is.
I know my distribution busbars and my fuse holders have plastic covers that probably will combust if exposed to fire. Or combust and cause a fire

edit here's more options - https://www.sculpteo.com/en/3d-learning-hub/3d-printing-materials-guide/heat-resistant-3d-printing/

 

[ArthurEld]

I am thinking the alternate layout is much more likely to have a major short.