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Old Sep 27, 2003, 08:15 PM
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Fl
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Gary,

I will be curious what mr schulze has to say about this.

Alot of us have his chargers......Hopefully it was a freak mishap........Too bad it was in that machine it was flying beautiful..

Well tonight i ran to get an extinguisher for my room where i charge and also for my car... I am not taking any chances...

I only posted the photos for everyone to realize that playing with lipos does pose certain risks and to take precautions.... the purpose was not for everyone to second guess what was done right or wrong.........As we all know gary has been using these batteries for a while and knows what he is doing... this was a freak mishap.

So hopefully we all learn from something like this to be carefull,things do happen..



Larry
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Old Sep 27, 2003, 08:42 PM
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Let's start over. Thank you for posting those pictures. Some (many) modelers still are saying that LiPo's are no more dangerous than any other chemistry and reporting these incidents will hopefully cause other modelers to be more careful with how they handle these cells. Did all the cells burn or just one. There have been some discussions on whether a burning cell would cause the others to ignite. Maybe this accident can throw some light on that subject, it's just too bad it happened but maybe some useful info will come out of it.
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Old Sep 27, 2003, 09:05 PM
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I had the charger set for 10 cells and it was 10S4P that was in the plane. I looked at the charger and it was at 39+ volts (not 40, forget what decimal), still at 8 amps (8200mah pack) and I went out to fly my sp400 pylon plane (also flying on lithiums, so it goes for a while on the 3S 2100mah pack). I only flew it 9+ minutes and landed. As I was removing the wing to unplug, my friend Mike Weiss yelled at me, and when I looked over, there was a very tall plume of thick black smoke, and 2 to 3 foot high flames, and he was pulling what was left of the plane away from his trailer by the tail (from about the rear of the canopy back is intact, but that's all that's left). He flies turbines, so he keeps a fire extinguisher in the trailer, which he used. It didn't do anything to the fire. Dave Elias got his extinguisher from his car, and it took quite a bit of spraying with the dry power type extinguisher to get the flames out. Complete loss along with the charger, which was sitting on the cowl of the plane while charging. I should not have been charging them in the plane, but as stated earlier, it's complacency from doing that many times in other planes over the last year. Secondly, I should have more closely monitored the charger, voltage and current,.. with the voltage approaching max. I've charged lithiums now hundreds of times, and that charger has worked flawlessly, so I guess I've become too "trusting". When I do the same thing over and over and over hundreds of times, I simply don't expect it to be any different on the next iteration. Wwhen hoppy asks about how many cells burnt, all of them, along with the plane.
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Old Sep 27, 2003, 09:20 PM
GBZealous
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I just got My 636 in yesterday......I would be interested in Garys' thoughts on NOT choosing another Shulze.....getting a Stricly Lipo Charger AKA the Astroflight?

Noah
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Old Sep 27, 2003, 09:23 PM
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I've only had my 636 w/8.06 software for about 1.5 weeks now. So far it's working super. I only have a max of 6S4P @ 8200 MAH which I've only hit at 6.5 amps.

I had no idea this charger would pump 8 amps in a 10S4P pack.

SORRY AGAIN GARY!

That's a rough one to stomach...

__________
Best regards,

Ron Osinski
aka - GMRO
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Old Sep 27, 2003, 09:50 PM
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Gary, my take on your last message is that the charger really didn't "burn out." From your description, it sounds as if you're saying that something in the total charger-pack system failed. In other words, either the charger malfunctioned and caused the pack to fail, or the pack failed due to its own problem unrelated to the charger. As best I can tell, you have no way of knowing whether the charger or the cells was the source of the problem. The only thing you know is that the cells failed and burned down your aircraft. Is that about right?

>> He flies turbines, so he keeps a fire extinguisher in the trailer, which he used. It didn't do anything to the fire. Dave Elias got his extinguisher from his car, and it took quite a bit of spraying with the dry power type extinguisher to get the flames out.

This is a critical data point. Think about the implications here: A fire extinguisher owned by a turbine flyer would not put out a LiPo fire. Either the turbine flyer has an inadequate fire extinguisher, or LiPo fires are pretty darned nasty, and to be avoided by any reasonable means.
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Old Sep 27, 2003, 10:05 PM
GBZealous
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There are 4 types of Fire extinguishers
http://www.hanford.gov/fire/safety/extingrs.htm#fetypes
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Old Sep 28, 2003, 12:00 AM
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Quote:
Originally posted by Dave Hederich
Think about the implications here: A fire extinguisher owned by a turbine flyer would not put out a LiPo fire. Either the turbine flyer has an inadequate fire extinguisher, or LiPo fires are pretty darned nasty, and to be avoided by any reasonable means.
I think before anyone jumps to any conclusions (not to say you are, Dave), we need more facts. Many of the turbine guys use the Indian Fire Pump type of extinguishers, which use plain water and are intended for grass fires.



This may be a case of simply the wrong type of extinguisher for this type of fire or it may have been improperly used.

Data, we need data.

Daren
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Old Sep 28, 2003, 01:06 AM
BEC
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Interesting and scary. And truly sad to see this happen to a gorgeous and good flying airplane.

It will take rather more info to sort this one all the way out.

Schulze's documentation (as currently posted on is web site) says the 636 can "only" do 6.5A into 40V so if it was at 39V and still indicating 8A that indicates something was not right.

I echo the question about what the source power was. Even if the charger is 100% efficient in stepping up the voltage it would have to be drawing nearly 30A from a 12V source to put out that much current at 40V. That's a hefty power supply or a BIG deep cycle battery. I wonder, lacking any information, if the innards of the charger were somehow damaged/weakened by something other than a pure DC input - perhaps not even on this charge cycle. Schulze is rather strident in his documentation about how most power supplies and no battery chargers are suitable as sources.

As for the 8.06 software catching a cell count error...... I've just put 8.06 in my 330d and 636. The 330d is batting .500 in catching an intentional cell count error. I wouldn't depend on that function at all (the test was with two 3s packs and setting the charger to 4). I haven't tried the 636 yet to see if it's any better.
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Old Sep 28, 2003, 05:25 AM
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Bernard, supply is 115AH deep cycle marine battery.
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Old Sep 28, 2003, 06:42 AM
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"... It will take rather more info to sort this one all the way out..."

BEC, we may never know. Something like a partial gap in a connecting wire (hidden mfg. defect) causing high impedance won't be found. If not in this case, then another down the road.

Something Fred Marks said has stuck in my mind: "Safety is a matter of discipline". It's a pain, but "taking pains" limits the loss to the pack per se and, possibly, the charger.

Gary, I don't know you except for your participation on ezone, but I feel sorry for your loss.

- RD
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Old Sep 28, 2003, 06:55 AM
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Quote:
Originally posted by Daren
I think before anyone jumps to any conclusions (not to say you are, Dave), we need more facts. Many of the turbine guys use the Indian Fire Pump type of extinguishers, which use plain water and are intended for grass fires.


On a related note, the extinguisher pictured is suitable only for class A fires. A turbine model has a whole lot of flammable liquids in it, and using water is an invitation to spread the fire. Since almost all flammable liquids float on water, they will just run off downhill, happily burning atop their cushion of water.

Those who are using these pressurized water extinguishers for turbine models should get rid of them immediately and get hold of CO2 or dry chemical extinguishers rated for the threat they actually face.

Similarly, multi-class extinguishers would seem to be indicated for LiPoly fires, especially where there may be proximity to a 120 volt power supply. Spraying water on energized electrical equipment is not a good plan.

Matt
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Old Sep 28, 2003, 07:04 AM
luc
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My feeling is the following: charging close to 40V at 8A gives a lot of watts, a lot of heat. I would not charge at that level, because that's too much heat generation.
Presently with my SC2, even if it can charge at 4A*2, I prefer to avoid overheating and stay at much lower amps, even if it takes more time. I prefer to have an extra battery pack and give a low charge: better for the charger and certainly not bad for the packs.
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Old Sep 28, 2003, 07:39 AM
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Yes, Daren, I also would like to have more information on that first charger. As I said, it may have been an inadequate charger for a turbine owner to have, or LiPo fires may be unusually stubborn. Note that the second dry powder extinguisher took "quite a bit of spraying" to put out the fire.

Gary, sorry if it seems as if we're grilling you here. It's just that the details of what happened in your experience could save others in the future. Do you have any way of knowing what type of extinguisher the first one was? It sounds as if that's a type for LiPo users to avoid.
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Old Sep 28, 2003, 07:44 AM
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Quote:
Originally posted by Dave Hederich
Yes, Daren, I also would like to have more information on that first charger. As I said, it may have been an inadequate charger for a turbine owner to have, or LiPo fires may be unusually stubborn. Note that the second dry powder extinguisher took "quite a bit of spraying" to put out the fire.
Dave:

Don't get too hung up on the "quite a bit of spraying". Dry chemical extingushers work by smothering the fire. You have to get sufficient agent on the material involved in the fire to cut off the supply of oxygen. This can take a bit of effort.

You also have to be careful if the material involved has the capacity to retain a lot of heat, because removing the layer of agent can allow the fire to re-kindle.

Matt
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