View Full Version : LiPo "fireproof" bags: a test

05-13-2015, 08:53 PM
I figured I'd actually put one of my LiPo Guard bags to the test.

Using a "fat boy" blowtorch, aimed into the open cavity of the bag (the inside, where a battery would lie) for two seconds, set the bag itself on fire in less than two seconds. After it was on fire, I flipped it over and fumbled for my phone to take a picture; it kept going a bit after this, too.


I'm wondering whether using these bags would just add fuel to whatever fire, rather than protect anything.

My conclusion: If you worry about LiPo fire, charge in a metal bowl or on a ceramic plate. And low-cost Chinese products are, indeed, low-cost.

05-13-2015, 11:51 PM
Is that thing made of vinyl?!?

A bag made from anything less than fiberglass or aramid fabric, then maybe coated with aluminum and/or silicone is almost certainly adding fuel to the fire. Fiberglass melts with enough heat while aramid (nomex, kevlar, etc.) simply decomposes; neither of them can effectively fuel a fire. Hydrocarbon-coated (most rubbers and polymers) natural fibers and pretty much all synthetic fibers are just fuel that turn into gooey, sticky third-degree burns.

If you are paranoid, bury the batteries in the middle of a large clay pot or metal bowl filled with playsand. The sand is cheap and will pretty well insulate the bowl and furniture from the heat of a fire.

05-14-2015, 11:14 AM
Here's a picture of the inside. I think that may be a glass-derived fiber, which as you said "decomposed," but it transmits enough heat that that doesn't matter -- the outside catches on fire.


05-15-2015, 11:58 AM
Interesting, though I wonder if temperature-wise, your blowtorch is a valid analog.
Looking around the net you can find tests with actual lipo in knockoffs "safety bags" that look much more scary than that though...

Sand-filled clay pot for charging FTW!

05-15-2015, 03:40 PM
Sand-filled clay pot for charging FTW!

Or, you know, be there, and be quick if you see/smell/feel anything resembling puffiness or rupture...

My main reason for this is actually that I'm taking a few batteries on a plane to go to Boston in two weeks. I want at least SOME level of protection... I think a small Pelican case specifically for the batteries would be better than these pouches. Maybe put the batteries in the pouch, in a clamshell?

05-15-2015, 03:55 PM
All this talk about fires is making me paranoid!

+1 to the Pelican case.. batteries and most robots, important devices, and ground stations get a Pelican case for transportation around these parts :p

05-15-2015, 05:31 PM
My main reason for this is actually that I'm taking a few batteries on a plane to go to Boston in two weeks.


The current IATA dangerous goods regulations and your rights as passenger to carry the LiPos with you in carry-on luggage but not in your checked luggage. There are 3 classes of LiPo batteries. Below 100Wh there are no quantity restrictions as to the amount of batteries you can carry. Between 100Wh and 160Wh you are limited to two battery packs total per passenger. Above 160Wh you are not permitted to carry the packs as carry-on. Let me know how it goes. I'm trying to figure out how to transport Golem and its batteries.

05-15-2015, 09:16 PM
Yes -- I'm banking on those regulations! That being said, when I move soft pouch batteries around, I don't want the softness to be a significant issue to my ability to have working batteries when I get to the destination :-)
I will undoubtedly report back.

05-16-2015, 05:34 PM
Maybe these rules are consistent between companies in the US, but check what the company has to say before packing, all the more if you fly internationally. I've flown a lot at the end of last year and surprisingly some companies have quite different rules. Some will not be happy about unique cells and limit heavily the number you can carry or completely ban them, while they might have less stringent limitations for batteries inside products.

If you define the robot as a product, maybe they would consider differently the batteries when they are in the robot, and when they are packed separately...

05-16-2015, 11:04 PM
Some will not be happy about unique cells and limit heavily the number you can carry or completely ban them, while they might have less stringent limitations for batteries inside products.

The checkpoints are run by the airport or authorities, not by the airlines themselves. Thus, for hand luggage, while the companies may have different written policies, they may have a hard time enforcing those.

For checked baggage, the problem is that cargo may ride in colder/less pressure environments than passengers. This may cause rupture if the cells aren't designed for it, and if there's a fire, it's much less quick/convenient to put it out. I think the only reason we're allowed to send equipment with LiPos installed, is that it's too much of a hassle to try to get everyone to open the gear and take it out (some gear doesn't even have that option.) Note that they count "power bank" type devices as actual "batteries," not "devices with installed batteries."

My robot has lots of big holes (lots of "webs" for structure, rather than big plates) so the battery isn't all that enclosed. I plan on taking it out for travel. I also plan on bending a bit of polycarb on the heat strip to make a cover for the parts that can be shot by an enemy mech -- I wouldn't want a well-placed shot to make the bot go up in smoke...
I have 11 days to do it!

05-17-2015, 07:24 PM
I've flown with lipo and li-ion batteries many times, all explicitly below the 100Whr limit. If they are soft packs, I put them in a fireproof bag, inside a cardboard box for rigidity, and some padding inside the box around the fireproof bag to keep them from bouncing. And yes, always as carry on. I've never had a screener even comment on them, but they will if you pack a motor and a bag of random wires!

I guess a few dozen successful flights doesn't really put that good of a bound on how well that technique works, but at least I feel comfortable with it.

05-17-2015, 10:55 PM
Overkill is my middle name!