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Lipo Bags Rule OK!

Lipo Fire..Lucky Escape

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ChrisB02/07/2017 21:04:01
1220 forum posts
34 photos

I had an email from a club mate today. He woke up in the middle of the night and thought he could smell a bbq as it was a hot night and the windows were open, he looked around the house and found nothing so went back to sleep.

The next day he went into his modelling room and found his Lipo bag shredded and several lipos melted. All lipos had deans connectors and hadn't been touched for several weeks due to him being unwell. The Lipo bag saved the day....just!!

I've been to the local army surplus store today and invested in some ammo boxes and will also be making sure my lipo bags are up to scratch!!

lipo fire 1.jpg

lipo fire 2.jpg

lipo fire 3.jpg

Edited By ChrisB on 02/07/2017 21:07:03

Dave Hopkin02/07/2017 22:22:13
3672 forum posts
294 photos

Only ever had one Lipo go up (my own fault) and there was virtually nothing left of it bar a few shreds of wire - so the photos of the Lipos surprise me

John Bisset02/07/2017 22:33:05
237 forum posts
6 photos

Ouch. What does your friend think started it?

I use a stainless steel box about 30cm eachs ide (old surplus item), with the Lipo bag inside. I wondered if that was OTT - I think I've decided it is not.

John

Bob Cotsford02/07/2017 22:33:40
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8941 forum posts
498 photos

I've 'discharged' a few for disposal and found that some do unpack themselves while others just blow out one side. I've moved storage for my LiPos out to the concrete garage and also use neoprene lined ammo boxes both for storage and for transporting them.

Simon Chaddock02/07/2017 22:46:58
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5844 forum posts
3100 photos

If all those 'blown' LiPo were in the same bag then it is not surprising they all went up.wink 2

Individual physical separation is a vital safety feature.

ChrisB03/07/2017 09:01:52
1220 forum posts
34 photos
Posted by John Bisset on 02/07/2017 22:33:05:

Ouch. What does your friend think started it?

I use a stainless steel box about 30cm eachs ide (old surplus item), with the Lipo bag inside. I wondered if that was OTT - I think I've decided it is not.

John

No, he doesn't know. None of them were puffed and he'd left them as they were, without any checking of capacity/charge.

I think a lipo bag inside a box is a good idea! Ideally each lipo should be individual such that is can't spread to its neighbour but that's not realistic when you have more than ten or a dozen.

The Wright Stuff03/07/2017 09:13:21
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1402 forum posts
227 photos
Posted by ChrisB on 02/07/2017 21:04:01:

and hadn't been touched for several weeks due to him being unwell.

That's the aspect that concerns me most. If we believe it to be literally true, then why did the fire occur then (and not earlier or later)?

What changed?

The only possible provocation must be temperature change, surely?

ChrisB03/07/2017 09:25:23
1220 forum posts
34 photos

Its difficult to know. They are the only lipos he had. Never abused through charging or impact etc. Only used in his glider a few times a year. It looks as though the fire started on the right hand side of the photo above, that looks the most charred.

Tim Flyer03/07/2017 10:31:28
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1397 forum posts
251 photos

Good post. I keep mine in my workshop shed away from the house. I have two separate steel boxes and use LIPO bags inside. Separating each LIPO into separate bags and boxes would be impractical as I have quite a few. I think one possible reason for a fire is if a soldered connection on a deans plug breaks. The deans plugs don't have proper sleeves for the two wires and rely on shrink wrap. If a solder joint fails and there is any uncovered portion on the plug there is a chance of shorting. I have seen some club members wrap elastic bands round the battery and leads when putting them away to keep the leads from moving . Maybe that helps?

Edited By Timothy Harris 1 on 03/07/2017 10:32:09

ChrisB03/07/2017 11:22:14
1220 forum posts
34 photos

That had crossed my mind. I suppose that over time the wire and or insulation can wear. I think i'll stat storing them with bands over the wires.

CB

Kelly03/07/2017 11:30:18
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1241 forum posts
191 photos

Have any model shops reported lipo fires,they must be at more risk with the amount of lipos in stock???

The Wright Stuff03/07/2017 12:37:25
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1402 forum posts
227 photos

The fact that model shops are not burning down left right and centre underlines that LiPo's don't just spontaneously self-destruct for no reason.

Model shops stock them, lots of them. But they don't handle them, so failure modes like broken wires or shorted connectors would not be likely in that case...

Bob Cotsford03/07/2017 12:41:50
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8941 forum posts
498 photos

Model shop stocks would also be at storage level voltage as they come from the manufacturer.

Tim Flyer03/07/2017 13:28:54
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1397 forum posts
251 photos

Yep it's seems to be handling that's the danger. A solder connector popped off one of my charging leads yesterday, that gets a lot of handling. It was a "bought " multilead so not my handiwork 😊, so I guess the same can happen on a battery's lead, but luckily not often.

MattyB03/07/2017 18:12:05
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2418 forum posts
47 photos
Posted by ChrisB on 03/07/2017 09:01:52:
Posted by John Bisset on 02/07/2017 22:33:05:

Ouch. What does your friend think started it?

I use a stainless steel box about 30cm eachs ide (old surplus item), with the Lipo bag inside. I wondered if that was OTT - I think I've decided it is not.

John

No, he doesn't know. None of them were puffed and he'd left them as they were, without any checking of capacity/charge.

I think a lipo bag inside a box is a good idea! Ideally each lipo should be individual such that is can't spread to its neighbour but that's not realistic when you have more than ten or a dozen.

Posted by The Wright Stuff on 03/07/2017 09:13:21:

That's the aspect that concerns me most. If we believe it to be literally true, then why did the fire occur then (and not earlier or later)?

What changed?

The only possible provocation must be temperature change, surely?

No, not necessarily. Whilst extremely rare lipos can internally short due to dendrite growth - if the dendrites get long enough the anode and cathode meet. This normally requires long term storage of the pack at elevated (>4V/cell) voltages throughout the life of the pack, though. Another good reason for storing them at storage (~3.7-3.8V/cell) voltage!

Edited By MattyB on 03/07/2017 18:26:42

PeterF03/07/2017 19:14:05
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602 forum posts
743 photos

If storing in ammo boxes then I have seen some info and videos that this can be dangerous if a lipo burns because it builds up pressure. I believe the recommended thing to do is either drill some vent holes or remove some of the rubber gasket. I have removed some of the rubber gasket from mine as I both charge and store in ammo boxes. Remember, lipo bags do not seal, they will let the hot gasses vent, but hopefully keep flame inside.

Another caution about ammo boxes, make sure you do not shut the lid on the balance lead, that is one for the embarrassing moments award. Try and solve one problem to create another.

IanR03/07/2017 20:38:59
780 forum posts
4 photos

I can see I need to get an/some ammo boxes. There hasn't been an ex army surplus type store near me for 40 years or more. I've seen some on t'internet but would ask if anyone can point me at a particularly good buy - both for practicality and price.

Thanks. Ian

onetenor03/07/2017 22:08:19
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1901 forum posts

Those cases called flight or equipment/instrument case are handy for carrying lipos.Again drill holes for safety .

OZ e flyer03/07/2017 23:00:38
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152 forum posts
28 photos

I highly recommend looking at the bat-safe boxes. They are well constructed and make life easy for storing and charging lipos. Check out their web site. I know they're a little more expensive but for me that is money well spent. It's bought me real peace of mind that any alternative just couldn't achieve. I'm away often and the thought of a house fire from my batteries frankly scared the hell out of me. Not any more.

TP

Martin Harris - Moderator04/07/2017 01:02:55
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Moderator
9766 forum posts
264 photos

I'd be wary of so-called aluminium flight cases. Most of the cheaper ones are some form of cardboard/fibre composite faced with thin aluminium foil. The composite is combustible and I suspect that the foil would burn through very quickly.

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