Ammo Can LiPo Storage
 

I am wondering it it would be safe to store LiPo Batteries in a metal Ammo Can, with separators to keep the batteries from touching and shorting each other out?

Someone may come along and correct me, but I believe that steel ammo cans are an acceptable way to store Lipos. I keep old unused working Lipos in one, but I use those fire-resistant storage pouches for my frequently used batteries.

The part where I am unsure is that I understand that when Lipos "cook off", the fire is extremely hot (as in capable of melting/burning through asphalt), so I don't know if that thin ~20 gauge steel is thick enough to not get burned through by a Lipo on fire. In that case, it might not be good enough, but it is still way better than nothing.

Regarding using separators, that is never a bad idea, as redundancy is a good thing in the safety department, but I don't think it is really necessary. The battery bodies touching each other has no effect on anything, and battery plugs are generally made so that there is no exposed metal, which could touch other connectors, cause a short circuit, and a resulting fire. But, imagine something like a paper clip dropping in there and bridging two connectors. In that case, dividers would prevent any potential problems. Extra safe, but mainly for extra assurance, as I don't think it is really necessary (unless you do have exposed metal on your connectors, then separators would be mandatory).

I hope this helps some.

A lot of people use the ammo cans for LiPo storage. While they will not melt, they will be pretty toasty on the outside (red hot) if the packs that are inside start to cook-off and the over-pressure generated but the pack's cooking off will cause the cans to distort and (possibly) pop the lid up.
For portability, using ammo cans is better than throwing 8 or 10 5000mAh 6S LiPo in the back seat on the way to the field.

I have gotten in the habit of drilling a 3/8 hole under the latch to relieve pressure in case of a fire.

We did several tests and the ammo cans with vent worked as good as any of the best purpose built lipo vaults. We save old lipos and when we have enough we run a clinic at the field where we put several old packs inside and over charge one of the larger packs till catastrophic failure.

Good to demonstrate containment of lipo fires. Just a point of interest is always containing is not as important as making sure nothing flamable is near because as said the can can get hot enough to ignite flamable material close to the can.

Also a good demo of the amount of very toxic smoke and fumes from a lipo fire.

Eye opening for those who have never seen a lipo fire.

Ammo can mods
 

If you don't want to drill vent holes in the can, simply cut out several sections of the rubber gasket that seals the lid. That way the lid latching mechanism remains under tension and stays latched, yet the can will not over pressurize and burst open in event of a fire. It is important that the gasses coming off the burning LiPo's is vented while still containing the flame jets emanating from the LiPo's inside. Burning LiPo's can produce a significant flame jet/blow torch several feet long which must be contained to prevent ignition of nearby combustible materials. That is the purpose of the can. I lined the inside perimeter of the can and made divider/insulators out of corrugated cardboard for the inside of my 50 cal ammo can. This allows the batteries to be stored vertically and keeps the plugs and balance ports insulated from the other batteries. Keep the storage cans on noncombustible surfaces (a concrete floor) and separated from adjacent combustibles, the same as you would do for a stove or fireplace. 3 to 4 feet should be sufficient.

The hole drilled under the latching mechanism in no way interferes with the integrity of the latch. The latch when closed helps block/deflect any flames from the vent hole. Note the area the latch covers when closed. Open the latch and lid and drill your hole as close to the middle of where your latch will be when closed. The latch now covers the hole with about a quarter inch space behind the latch for venting and deflecting any flames that might come out the hole.

I finished rebuilding my ammo can LiPo storage box. I have been doing some siding on the house and I read that the material (James Hardi Plank from Lowe ) is flame retardant, so I tested it, and it will not burn but does transfer about 90% of the heat trough the board. From what I was able to find LiPo batteries burn at about 8-900 degrees,
the MAPP gas I tested with is reported to burn at just under 2000 degrees. I let if run on the torch for 10 min. and you can see the results, will not burn but does come away very brittle after the fire.
So I lined the inside of the box and made some separators and a second shelf, as well as a lid before closing the box. I did drill a 3/8" hole under the latch to vent pressure. I am not sure the hard board will do anything in case of a fire, but at least it made separators that will not burn
.The second pic is just after turning the board over to see the transfer.
https://cimg7.ibsrv.net/gimg/www.rcu...ed7c2ed98a.jpg
https://cimg4.ibsrv.net/gimg/www.rcu...58c2a20423.jpg
https://cimg5.ibsrv.net/gimg/www.rcu...021f018798.jpg
https://cimg6.ibsrv.net/gimg/www.rcu...d68a4cc4e8.jpg
https://cimg7.ibsrv.net/gimg/www.rcu...4cf3a3eb1b.jpg
https://cimg8.ibsrv.net/gimg/www.rcu...b4bda4c877.jpg

Jeff,

Hardiplank has been laboratory tested and has an flame spread rating of 0 and a smoke production rating of <5 per ASTM E84 (Steiner Tunnel Test) which compares a test sample's burning rate and smoke production rate against those of known samples of noncombustible cement-asbestos board (rated at 0) and dried red oak (rated at100). Your test matches the results of the lab test. Because it is highly fire resistant, it is a great choice for homes surrounded by woods and other combustible vegetation, commonly referred to the wildland/urban interface.. I had not considered Hardiplank, but that certainly is an excellent option. Just a little harder to cut. Nice job on lining the box too.

What are a few more cuts, I am half way trough a full pallett of the stuff, lost count of how many saw blades so far.

If you get a set of those shears that attach to a drill, you won't ruin any normal saw blades. I re-sided my entire house that way, powering it with a Ryobi cordless drill. And no dust to breathe.

Milwaukee saw blades
 

The new style of saw blades last a lot longer.

I have not yet moved on to lipo due to the need for more precautions over nimh for my RC cars but this seems like a decent precaution measure and not too annoying

On my ammo can I drilled a hole in the front, just under the latch flap, and covered it with a decal that usually comes with RC stuff. That way when one does decide to grenade itself, it’s got a pressure release. I also put some of those stick on “drone feet” under the handle in case I gotta make a quick grab and toss. That still was pretty tough to drill through, so I don’t see an issue using one to store smaller FPV type 1500 mah batteries.

I like the hole under the latch idea. Just got my 1st set of Lipos. I just ordered a bag last night. I may end up using an ammo can I’ve had for many years. I’ve just had it for 30 years and hate to ruin it lol.