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Build yourself a better (and bigger) fireproof charging box instead of using a small lipo bag.

Firejay27

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Austin, Texas
I've got a few of those Lipo bags for charging and storing batteries but I really don't like them. I also charge my batteries inside the house because out here in the Texas heat, even in the garage it's too hot to safely charge. I don't just charge drone batteries though as I build my own 18650 and 21700 battery packs for other uses. Charging my home made packs and multiple drone batteries just doesn't work well in the small lipo bags so I decided to build one myself.

I started off with a fireproof document box with a 2000 degree rating. I then took Ceramic Fiber fireproof insulation with a 2400 degree rating and wrapped it in weld cloth that has an 1800 degree rating. This goes on all four sides as well as the lid which closes snuggly. For the base I used fireproof bricks (2700 degree) which are the same ones you use under a fireplace. The bricks are very lightweigt so you can still carry the box around with little effort. Your power cord is run out through the top maintain a seal once the lid is closed. This one stop the deadly smoke but it will keep the flames and heat in the box.

To test I took a torch to a section I used for proof of concept and tried to burn it. Worked very well. Since an average lithium fire from these batteries doesn't reach more than about 800 degrees I should be good.

Just thought I would pass this on for anyone worried about charging batteries inside or lives in an apartment and wants to keep things safe and have room to charge more than a couple batteries at a time.
 

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I had looked at those as well before starting my DIY version. These were still too small for my use. The document box is 2.5 times larger and a lot deeper than the Bat-Safe. I have 10 DJI batteries and I can charge all of them at the same time in my box if needed. I can also charge up to 4 banks of 21700 4s batteries so the larger size was needed.
 
Why not use a standard ammo box?
A metal ammo box is dangerous simply for the fact that it's metal. The burning battery inside can heat up the container well past the flash point of paper which is about 475 degrees F. Not to mention it has many gaps. I also needed a larger box. An ammo box might be ok if you lined it with some of the materials I used but then again you would cut down the space available for charging.

Take a look at this example from 4 years ago:
 
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I've got a few of those Lipo bags for charging and storing batteries but I really don't like them. I also charge my batteries inside the house because out here in the Texas heat, even in the garage it's too hot to safely charge. I don't just charge drone batteries though as I build my own 18650 and 21700 battery packs for other uses. Charging my home made packs and multiple drone batteries just doesn't work well in the small lipo bags so I decided to build one myself.

I started off with a fireproof document box with a 2000 degree rating. I then took Ceramic Fiber fireproof insulation with a 2400 degree rating and wrapped it in weld cloth that has an 1800 degree rating. This goes on all four sides as well as the lid which closes snuggly. For the base I used fireproof bricks (2700 degree) which are the same ones you use under a fireplace. The bricks are very lightweigt so you can still carry the box around with little effort. Your power cord is run out through the top maintain a seal once the lid is closed. This one stop the deadly smoke but it will keep the flames and heat in the box.

To test I took a torch to a section I used for proof of concept and tried to burn it. Worked very well. Since an average lithium fire from these batteries doesn't reach more than about 800 degrees I should be good.

Just thought I would pass this on for anyone worried about charging batteries inside or lives in an apartment and wants to keep things safe and have room to charge more than a couple batteries at a time.
what are the dimensions. many document fire boxes are 12x15X10" or other variations with interior padding: Why need add'l ceramic fiber insulation?

Fireproof and water-resistant: Fireproof lock box is made of double layered non-itchy silicone coated fiberglass which stands up the temperature up to 2000℉.It has been passed by SGS TEST(UL94 VTM-0 Certified).Fireproof file box is not only fireproof but also high water resistant in case it gets wet for any reason
 
Dimensions are 15.5 x 12.2 x 10

I went with the extra insulation and extra effort just to be on the safe site. The box I got states it's supposed to be rated up to 2000F but it didn't say for how long. I know LiPo fires can reach 800F so yes that should be plenty. With the extra layers though and having a lid with the layers as well makes me much more comfortable charging indoors. With the extra layers as well there's a good chance that if you have a fire that the box will be reusable and you don't have to start from scratch. Hopefully I'll never have to put that to the test.

I think I mentioned it in the OP though that I wanted to be able to charge multiple batteries at the same time seeing that I have quite a few between three drones. While one battery may burn at 800F if it triggers the others then it could get much hotter and burn a lot longer. The extra layers allow for that longer burn time.

If you've ever watched video's on those LiPo burn bags, I wouldn't trust them for anything if I'm indoors. Many of them melt into a big mess and many allow flames to shoot out of them.
 

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