DIY Portable Battery Bunker - RC Groups
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Dec 13, 2017, 06:21 PM
Registered User
Mini-HowTo

DIY Portable Battery Bunker


DISCLAIMER! This is NOT tested and if you build it I am not responsible in any way, shape or form.
If someone builds this and tests it, I would love to see the results!
I designed and made 2 versions of this portable battery bunker based on info I found on the internet. It uses a Wal-Mart Hyper Tough tool box and .5" drywall. The difference between the 2 versions (only the first one is shown) is the order the drywall pieces are assembled in the tool box. The drawing has both dimensions on it. Follow the numbers closest to the drawing for the original or the numbers under the star for option 2. Unless you compare them side-by-side you will not notice a difference. You must use the actual dimensions in parenthesis to use a 23.75" x 23.75" piece of .5" drywall. The carbon felt filter in the lid has a working temperature of 1800F. It is non-flammable and non melting. The tray support brackets must be removed out of the box. I tried 3 methods and the best way I found was to drill out the 3 spot welds for each bracket. I used a .25" bit. I scored and snapped the drywall so as to not lose material. If someone cuts it with a saw, I would like to know how that worked out. I think that would be easier and maybe make better edges. I used masking tape on the top edge to increase durability and prevent dust. I glued the pieces in with Liquid Nails construction adhesive. I did not glue anything to the box itself. I did not do a very neat build, but I think it will serve the purpose.
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Dec 13, 2017, 08:54 PM
Registered User
I use a Walmart sold Honeywell Fire Safe box for my battery bunker. I have two of them. I store my nicads in one and charge in the other. They have a latch but are not sealed in any way. The walls are thick and contain fire resistant material between layers of steel.
Dec 13, 2017, 09:24 PM
Registered User
Nice job. Did you drill out the three holes in the top for venting?
Dec 14, 2017, 09:51 PM
Registered User
Quote:
Originally Posted by quigly7777
Nice job. Did you drill out the three holes in the top for venting?
Yes. .5" at 4" spacing.
Dec 15, 2017, 02:31 PM
Registered User
Thanks!
Jan 02, 2018, 05:19 PM
Brian Stark
Does anyone know where a person can find the high temperature carbon felt? I've tried the three local big-box stores with no luck, the closest thing they have is high temperature welding blankets but I don't think they would allow much air to escape if there was a fire.

Even stopped by the local fireplace/wood stove shop and the owner told me no such thing exists. I can find plenty carbon felt filters but none of them specify the temperature.
Jan 02, 2018, 05:56 PM
its a fart.
poofntime's Avatar
a welding blanket would allow gas n air to pass thru it.. i would not worry about allowing gas or air to pass.
Jan 03, 2018, 08:58 AM
Brian Stark
Quote:
Originally Posted by poofntime
a welding blanket would allow gas n air to pass thru it.. i would not worry about allowing gas or air to pass.
I'll try that then, thanks.
Jan 03, 2018, 11:20 AM
LUFTGUCKER
Mach 9,this looks great,I'll will use a similar battery pattern but instead the sheetrock I will use concrete reinforced with wire mesh,cutting out the foam blocks the size of the batteries I m using I will line them up nicely and pour really thin (Driveway fix)synthetic Quick pour Crete with wire mesh inserted around the styro,when the cret is set pour some solvent into the mold to eat the foam,done!
Jan 03, 2018, 12:41 PM
Registered User
Quote:
Originally Posted by lotsasteam
Mach 9,this looks great,I'll will use a similar battery pattern but instead the sheetrock I will use concrete reinforced with wire mesh,cutting out the foam blocks the size of the batteries I m using I will line them up nicely and pour really thin (Driveway fix)synthetic Quick pour Crete with wire mesh inserted around the styro,when the cret is set pour some solvent into the mold to eat the foam,done!
I would like to see that when you are finished! Maybe some plans?
Jan 03, 2018, 12:51 PM
Registered User
Quote:
Originally Posted by Boone 870
Does anyone know where a person can find the high temperature carbon felt? I've tried the three local big-box stores with no luck, the closest thing they have is high temperature welding blankets but I don't think they would allow much air to escape if there was a fire.

Even stopped by the local fireplace/wood stove shop and the owner told me no such thing exists. I can find plenty carbon felt filters but none of them specify the temperature.
I used the Tillman 615B 3' x 3' 16oz thermofelt medium duty welding blanket. They do not specify a thickness but I would call it 3/16". The best place I have found it is at https://store.cyberweld.com/panfelwelbla.html and right now it is on sale. If you add something to the order to make it $25 or more then the shipping is free. I think it will vent the hot gas to reduce pressure while filtering the soot and ash without burning.
You may also try https://www.ebay.com/itm/Steiner-316...19.m1438.l2649 but it is smaller and more expensive.
Jan 03, 2018, 01:16 PM
Registered User
I don't think the fiberglass welding blankets would work very well. They have a lower temperature rating, are stiff and I don't think would work as a filter. The carbon felt is what is used by NASA and I think NASCAR. It is also used for grills and has many other applications. You might check on YouTube for ideas. I also used it to make a LiPo pouch with fire retardant thread (Nomex) to place inside of a regular fiberglass LiPo pouch for charging. I made a pouch for a backup hard drive and keep that in a fire/water safe. I figure if a storm slams the safe around it will have a second function as a cushion. I considered using stainless steel wire instead of thread like I think NASA does. Note that the material will fuzz off when handled.
Jan 03, 2018, 01:22 PM
Registered User
I did not mention it, but on my plans I state that I cut the felt to 7" x 32" and folded it in half to make it double thick. I also added a wire to hold it in the lid through 3/16" holes drilled in the end of the lid 7/16" down from the peak. It is not shown in the photos.
Jan 07, 2018, 11:09 AM
Brian Stark
Quote:
Originally Posted by 9Mach
I used the Tillman 615B 3' x 3' 16oz thermofelt medium duty welding blanket. They do not specify a thickness but I would call it 3/16". The best place I have found it is at https://store.cyberweld.com/panfelwelbla.html and right now it is on sale. If you add something to the order to make it $25 or more then the shipping is free. I think it will vent the hot gas to reduce pressure while filtering the soot and ash without burning.
You may also try https://www.ebay.com/itm/Steiner-316...19.m1438.l2649 but it is smaller and more expensive.
I found something similar on Amazon and ordered it, looks close to what you recommended. Should be here tomorrow, I'll report back after I receive it. Hopefully it works, if not, I will order the Steiner velvet from eBay.
Jan 12, 2018, 11:34 PM
Brian Stark
Quote:
Originally Posted by 9Mach
I did not mention it, but on my plans I state that I cut the felt to 7" x 32" and folded it in half to make it double thick. I also added a wire to hold it in the lid through 3/16" holes drilled in the end of the lid 7/16" down from the peak. It is not shown in the photos.

Instead of drilling holes and running wire to hold my carbon felt in place, I used Liquid Nails and glued it to the top of the lid. I'm not sure if the Liquid Nails will hold up in much of a high temperature but, the felt is there mainly to keep flames from shooting out of the top of the box in case of a fire. I hope it will be good enough.

The felt I went with is from Amazon and is 3/16 of an inch thick, 18 inches wide by 24 inches long. $18 on the price and free shipping with Prime.

Overall I am very happy with the completed bunker. It looks like it will be very durable over time and very easy to load up and take to the flying field. The only thing I would do different if I were to do it again is glue carbon felt (or use 1/4 inch sheet rock) to the bottom of the toolbox on the inside instead of half-inch sheet rock. One of my 5000mAh 6S is a little too tall to get the lid shut on the box without putting pressure on the battery if it is towards the front. My other 6S battery from a different manufacturer fits fine.

Thanks for sharing, 9Mach


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