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Old Apr 28, 2012, 11:17 AM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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Quote:
It's kind of late to deal with a LIPO problem once a flaming spewing toxic smoke emitting mess is in your house.
LiPolys do not go from charging just fine to a crital mass in a matters of moments . Have you watched any of the numerious deliberate flaming LiPoys video and paid any attention to how much overchargeing they received before venting with flames.

Charge a LiPoly to 4.3V and it does not puff or vent, it will have a reduced life span however.

I have charged LiPolys thousands of times in my house and will continue to do so. I charge them attended and I do in fact pay attation to their charging. / balancing.

I have deliberated over charged LiPolys out in the open in a fire safe location and long before they reach critical state they are over 4.2 per cell, they heat up beyound 140F and they puff.


Read several hundred of hoppy's LiPoly Fire reported incidents.

Thiose which RC experienced are along the lines of ,was charging my LiPolys and went out to dinner came bachk to duened down house. Left LiPolys charging and remembered them several hours later rushed home and fire department was putting out the fire. Left LiPolys charging down in the basement or out in my shop and go a phone call or wife want me to do something for her etc.


Bottom line is if the cells volatges are normal, thier temperature is normal, they are not puffied or puffing are not over 4.25V ,the charge rate stsrted to decrease (CV stage) when the cells reached 4.2V then they are not going to be an issue.

Charles
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Old Apr 28, 2012, 12:12 PM
Who Dat!
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United States, LA, New Orleans
Joined Sep 2011
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Quote:
Originally Posted by C₄H₁₀ View Post
Could we extrapolate Schrödinger's cat-in-a-box concept to apply to lipo fires? Rather than killing a kitty, we just make it so your house is simultaneously perfectly safe and burning to the ground
only if we seal the house in a box and disallow anyone to view it.
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Old Apr 29, 2012, 12:05 PM
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Greensboro/H.Pt/Win-Salem P.T. Intl, North Carolina, United States
Joined Dec 2001
806 Posts
Hi Charles,
Do we still have lipo fires? Is it as common as when we first started using Lipos? Weren't most of the fires due to having the wrong cell count selected on non balancing chargers? When I first started using Lipos, I had to set the cell count and the charger was not smart enough to dispute my selection. With all the hitech chargers we have in the market today. Every charger now has balancing and even the cheap Chinese ones will tell you if you have the wrong cell count. I guess you could do NiXX mode but then you are asking for it.

What I would have like to see (4-5 years ago) was a poll on what charger was being used when the pack cought on fire. Were some chargers more susceptible to letting you make a mistake than others?

I have been using Lithium batteries in RC since Sony first put them in camcorders. In the begining I sat there the whole hour+, but now I am guilty of leaving the charging station 5-10 minutes at a time because of one excuse or other (wife, children, phone call, etc). I guess we get complacent after some time. We begin to trust the equipment more and more as time goes by. The gasolin in the car example is an exanmple, we dont think twice about keeping it in the attached garage.

We need to be more careful, I agree.

Vip.
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Old Apr 29, 2012, 01:37 PM
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seefest's Avatar
United States, MA, Bristol
Joined Sep 2009
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Electrical devices fail. People make mistakes.

The stories that concern me are the ones where the battery was not being charged. There was a guy on the other Lipo fire thread that had one burst into flames sitting on his kitchen counter.

Not very common, but it does happen.
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Old Apr 29, 2012, 02:27 PM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
34,760 Posts
Vip.

I started this thread long ago to answer that question and got opinions but no facts (direct answers).

http://www.rcgroups.com/forums/showthread.php?t=1206726

I do know of on incident with a major brand balancing charger that did start a LiPoly fire not to long before I started that thread.Best I could gather one of the firmware updates for that brand was the issue. It was a rev. which was updtaed(replaced) shortly after its' release but the chargers owners had not installed a more recent Ver.

I have posted numerious times that I do not like fireware revesions as it takes me on average 40 hours to go back and check for new bugs (errors / issues).

More recently a major brand charger was relesed with what I consider serious issues and even though it has been updated several times IMO it still has issues. No bad enough to flame a LiPoly but treats them a lot harsher than I care to have mine treated.

Also remember their are stiill a lot of non balancing chargers being used and many without external balancers or balancers which can not termintae the charge if a cell goes to high voltage wise.

I still use my Astro Flight AF109 (from time to time)which likely as a brand / model started more Lipoly fires than any other but only because users refused to follow very simple directions.It is still the best LiPoly charger I own to recover overdischarged LiPolys or to charge a single cell in a battery to get it up even with the rest.

Charles
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Old May 01, 2012, 01:24 PM
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United Kingdom, England, Ipswich
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I charge my LiPos in the garage - the charger and battery sit in a heavy and deep metal tray, and I have a sheet of metal nearby to drop on top of the tray if things get exciting. There are a couple of fire extinguishers within easy reach (3 distributed around the garage). I also have a thermal sensor under the pack, and the charger is set to raise an alarm and stop charging if the temperature gets too high.

Despite all that, when I'm charging I usually spend the time tidying up the garage so I'm never more than 10 yards away from it. I also monitor the pack every few minutes while it's charging.

But I still have a niggling doubts about LiPos!
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Old May 01, 2012, 01:58 PM
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hoppy's Avatar
Space Coast
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Quote:
Originally Posted by David Jenkins View Post

But I still have a niggling doubts about LiPos!
And well we should. Probably 99.9+% problem free, but bad things (like this) still are happening, so an ounce of prevention.........
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Old May 01, 2012, 02:10 PM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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I see from reading that thread that many still not not believe LiPolys create much pressure when the go thermal and they still do not understand that LiPolys do not need an external source of oxygen to burn. Nor do they understand the design purpose of Ammo Boxs.

Ammo boxs are to keep ammon ,dry and clean not prevent it from going off in a fire. Believe me I have seen what happens when am Armered Personal Carrier goes over a land mine or gets hit with an RPG. Believe me the M 16, M60 , 50 Cal.40MM ,90 and 105 recoilless rounds along with the C4 and C6,frag gernades etc. all end up being part of the explosion.

Charles
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Old May 01, 2012, 04:59 PM
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Greensboro/H.Pt/Win-Salem P.T. Intl, North Carolina, United States
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Hi Charles,
It is interesting how, in your thread, no one came up and said they have had a fire, let alone what charger they were using. Wonder why?
I still have a few of those non balancing chargers, now delegated to only doing 1S duty. I have retired one since I know it charges a cell to 4.3+V and I am not comfortable with that.

I keep my packs in clay pots and lipo bags, I have wanted to get a couple of ammo boxes; but, from your post above do you mean the ammo boxes are not safe for keeping the rest of the house going up in flames when one or more of these packs blow up? What is the safe way to keep them then?

Vip.
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Old May 01, 2012, 05:19 PM
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Space Coast
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AMMUNITION BOX TESTS
FWIW

UN-VENTED
Lipoexplosion in einer Munitionskiste (2 min 1 sec)



PROBABLY VENTED
- http://translate.googleusercontent.c...c5EH3lUqAe7Ixg
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Old May 01, 2012, 11:20 PM
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With all the batteries and chargers being purchased direct from China with no quality control at all, I'm surprised there are not more fires!
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Old May 03, 2012, 03:19 PM
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I've never had a problem with lipo reactivity / instability. Just toss the questionable ones, a policy I've recently applied to all parts after a few unfortunate incidents. I've noticed a lot of my problems are rooted in the fact that I push things to their breaking point. An ounce of prevention is worth a pound of cure, it keeps small problems (puffy lipo) from turning into big ones (onboard fire in flight).

You carry your cell phone in your pocket without worrying about a fire right?
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Old May 03, 2012, 04:01 PM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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Cell phones PDA, I Pods etc. mostly use 1S and they have on baord battery management systems. Most take several hours or longer to charge and they last 8 hours or longer per charge and yet from time to time they do go thermal, most of the time with after market (cheaper batteries) and after market (faster) chargers. Seems a bit like the ones many RCers use to me.

Charles
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Old May 04, 2012, 06:12 AM
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Joined Apr 2012
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I'm aware there are different operating conditions and that these usually include a smart circuit with a thermistor. I was only referring to the cell's construction material. Laptop batteries are multi-cell. Used properly, reliable, unmatched power to mass ratio. Most problems are due to operator error or carelessness, you'll get a warning before catastrophic failure in all but the most extreme cases.

Since you're splitting hairs, all but a few of these types of devices has an internal charging circuit and can't be charged at a faster rate under normal use.

My point was that these batteries are in common use. The difference between them that matters is that the responsibility for safe operation falls on the user, which is the weak link that causes the most failures.
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Old May 04, 2012, 06:46 AM
Electric only
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Graz - Austria
Joined Nov 2002
287 Posts
And your cameras and laptops are also stored in the garage ?

We tried it some weeks ago and had serious trouble burning a lipo. Older ones didn't do anything at all. Others needed 4-6s to get them burning after 1-5mins. A nail through the lipo just works with rather new lipos. Just a not so old, big and charged one did burn only by close circuit (90A). It also needed some time.

To the point of not using fuel in the house: isn't it common in the states to cook and heat with gas ? That's something I'm much more afraid of. There are regularly reports of fire or suffocation around gas. A Lipo is just a possible ignition source but represents not much material and no explosive power.

I have a much more lazy attitude around lipos. I always use a balancer as a safety device. But I charge at home without sandboxes.... I can hear the beeps but otherwise they are on their own. They are stored just in a wooden cabinet. Some are even a bit puffed, but as long as they work, it's fine.

And I sleep well :-)

I had one case of a near accident some years ago when I wasn't using a balancer, yet and chose a NICD charging program. The battery got puffed but the voltage must have droped because the charging stopped. Battery was dead of course. But that just means I must be more careful. I have some really badly damaged batteries (Funjet vs. earth). Most of them even deliver power and none of them burned. The accidents at our club field were screw through battery (unintentional) and two battery packs connected in the wrong way.

RK
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