So, after the ESC fire...

[Cpt Marvel]

Nite before last my ESC caught fire. I got a new one and motor today. The ESC was mounted directly under the battery. There is no damage to the battery THAT I CAN SEE, with the exception of a small scorch on the plastic. Is the battery still useable? Or could it be shorted?

What are the hazards of these li-po batteries? I have read about swelling, explosions. I was in Hobby-Lobby (of Hobby-lobby.com fame) today and they had a li-po charge back that a battery had blown in. What causes this? What precautions should be taken?

[osterizer]

If the battery isn't swelling and the foil isn't damaged it's probably still good. The Batteries and chargers forum has a lot of info. I would keep a careful eye on it for a while, maybe take a few short hops while measuring temps to make sure they stayed reasonable, and store it in a fireproof container.

The three things that usually kill lithium batteries are pulling too much current out of them, over discharge, and plain old overheating.

Too much current (especially a short circuit) or deep discharge can damage them physically, and either one can make them overheat. Do it a few times and they will get weak pretty quickly. Better still, at a certain temperature (I'm remembering around 200F, but I'm not sure; check the B&C forum for it), they get self sustaining and will burn up pretty quickly. Overcharging can do it too, which is why you have the warning not to charge them unattended. Videos and pictures of fires and the damage done from abused or ignored LiPos are easy to find.

The electrolyte is also said to be self-igniting if you expose it to air (by breaking open the pack when it has a charge), but I haven't tried that out yet :). You can short a cell through impact, also. For both reasons a crashed pack should stay in the ammo can.

[Cpt Marvel]

ummm...ammo cans. I like them...

Seriously; should I take an ammo can for say 5.56, which is pretty common around this here Army base, cut some holes for wires and put the bat in there while charging? Is it that much of a hazard?

[alan west]

ummm...ammo cans. I like them...

Seriously; should I take an ammo can for say 5.56, which is pretty common around this here Army base, cut some holes for wires and put the bat in there while charging? Is it that much of a hazard?

I have two ammo cans one for uncharged lipos and one for charging lipos. They are in the cans when being stored too. I love the smaller ammo cans the best. The lids can be removed to if need be.

AW

[simages]

Seriously; should I take an ammo can for say 5.56, which is pretty common around this here Army base, cut some holes for wires and put the bat in there while charging? Is it that much of a hazard?
lipo sack (http://www.youtube.com/watch?v=gSgjj6NT5U8) (3 min 8 sec)

I have two ammo cans one for uncharged lipos and one for charging lipos. They are in the cans when being stored too. I love the smaller ammo cans the best. The lids can be removed to if need be.
AWI use ammo cans as well for storage and if I leave home for an extended period, I place them in the oven. I'd go for 5.56mm at minimum, but I'd see what's around base many configuation to choose from. I currently charge in a Battery Bunker (http://www.batterybunker.com/) and have a Lipo Sack (http://www.batterystation.com/lithiumpolymer-liposack.htm) as well.

[osterizer]

ummm...ammo cans. I like them...

Seriously; should I take an ammo can for say 5.56, which is pretty common around this here Army base, cut some holes for wires and put the bat in there while charging? Is it that much of a hazard?

It's definitely not a huge hazard, but if you have 5.56 boxes lying around that you can charge the packs in, then by all means use them. There are those who people call the "Lipo-Nazis," who will excommunicate you and damn you to the 7th circle for charging a LiPo anywhere but in a 12" vault with automatic fire suppression. I dare say that isn't really necessary, but if you can isolate the packs while charging, it isn't a bad idea at all.

But... when you damage a pack it's different: as long as the pack is in the configuration and condition it was manufactured, it's safe as heck. If you damage it, then you have to put it on probation. Is it hot sitting on its own without any load? If not, then put it in a can and see if it's hot six hours later. If not, then keep it in the can and charge it, and so on. Treat it as a lump of stuff that may ignite at any time for a week or so. If it doesn't do anything untoward in that time frame, it should be ok. Understand though that damage can be 90%, and then the vibration of flying in a heli can finish the job.

Factory fresh packs are fine. Superficially damaged packs are usually ok. You can't tell if it's just surface damage without disassembling the pack, though, which would do a lot more than surface damage, so you're stuck: once you damage one, you can only be circumspect about trusting it again.

If all you did was scorch the outer shrinkwrap, you're probably fine, and all this discussion is just circling the field, but it's hard to tell by proxy when we're just typing on a forum. Without damage, LiPos are completely safe as long as you don't abuse them; once they're damaged you need to take a closer look, and keep them contained until you are sure they're ok. I don't want to think that you're fine and then have you wake up in a house on fire.

Keep it outside for a while, that's all.

[alan west]

I am not personally a lipo nazi. I just have seen a friends van packed with his audio gear............he sets up concerts at a live venue...$$$$$$ worth get charred by a lipo that he put on his charger in the back of his van. An RTF Trojan. Granted he crashed the plane while learning and the lipo may have been damaged. He walked away from his van while charging, which is not wise, came back and the insides of his van were burned up. I don't charge in my ammo cans at all times. Lots of times I remove the lid and set my lipo on the metal lid to charge it in open air. But I do not leave it unattended. I will fly other stuff while charging but I am close enough to put out a fire.

Just gotta have common sense.

AW

[osterizer]

Just gotta have common sense.

AW

Yep, no question. My point is to take reasonable precautions, not to tiptoe around them. What's reasonable, you get to know from learning, though-- if you have questions, then a couple of hours reading up in the battery forum is time well spent.