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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 06-30-2012, 07:24 AM   #1
rocco61
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Default Lipo fire

Have been running a Emax 2836-24 inrunner , 11.1v 2200mah 30C EZ Flite
Lipo Battery 6x3 prop and a 30amp ESC
in a wild hawk airplane. Always charged the battery at 2amps and
balanced it frequently. I live on 5 acres and fly over adjacent
vacant parcels that have a lot of dry grass this time of year. A few
days ago the front of the plane exploded and caught fire. The plane
crashed in dry grass about a 100 yards away. Fastest 100 yard dash I
think I ever ran. I was able to get the fire out before it turned
into the unthinkable. I had heard that lipo batteries could catch
fire if damaged or charged improperly. This one however just blew up,
one cell burnt up completely while the other two cells appear to be
undamaged, not even swollen . the battery had approximately 50 cycles
on it. I have talked to several of my friends , none of them have
ever had a lipo failure like this, they say usually the batteries will
puff up a bit when something is wrong and at that point they replace
the battery. I would like to continue to fly at home through the
summer , I am seriously considering going to nimh till the end of
the fire season at least. Did a search on EZ-Flite batteries didnt much on them.
Anyway I am looking for recomendations on lipo batteries. a brand that is least
likely to have any problems.
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Old 06-30-2012, 08:55 AM   #2
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Did the fire start after the crash or was it the fire that brought the plane down? Lipos burning (more often just a lot of white smoke actually) after a bad crash is not unheard of, if the battery is damaged in a crash then that can cause smoke and in a few cases fires from the battery. On the other hand, it's very very unusual for a battery that's in good condition, not subject to physical damage and not being over-charged or otherwise abused to simply burst into flames.
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Old 06-30-2012, 01:23 PM   #3
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I am with Steve....

Batteries do not consistently just burst into flames. I suspect something punctured the cell then yes they can burn and even explode. The lithium is very volatile when exposed to air. I saw this when the Horizon Corsair first came out. The motor mount screws were too long and if you pushed the pack those screws could and did puncture cells.

Also my ONLY battery fire was a NiCad pack - so don't think they are immune. It was an odd situation. It was a TX pack. I was testing at home. Standing over a sidewalk in the back yard. The battery cover came off - out came the 8 cell pack. It smacked the concrete - caused a direct short of the pack and started on fire. I kicked it into the grass and got it out quickly.

All of the store vast amounts of energy if release all at once.

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Old 06-30-2012, 03:24 PM   #4
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A short at a poorly soldered battery connector would be my first guess for an in flight fire on a system that had been performing normally.

A badly soldered (or crimped) joint can have enough resistance to get hot enough to melt. Battery connections and wires should never be hot.

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Old 06-30-2012, 06:49 PM   #5
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there was a loud pop, the canopy blew apart and a trail of smoke, no response from the controls, it fell out of the sky. the plane was on fire when I got to it, cant remember if there were any flames coming from the battery itself. the battery sits in the nose surrounded by foam, nothing there to punture it. this battery was pretty new and had not ever been involved in a crash. appears that of of the cells just burst, some kind of internal failure I suspect. all the solder joints are fine none of the wiring shows any sign of over heating. checked the current draw on the motor afterward. about 17 amps at full throttle , was at about half throttle at the time of the battery failure. about 10 amps. I take it that if I do everthing right and dont use damaged batteries, this would be extemely unlikely to happpen again ? what batteries are you guys using? probably nothing wrong with EZ-flite, but would like to use something that has good reputation for quality. I put together a 10c 2000mah nimh pack last night from AA cells and tried it out this morning. 3oz heavier , really makes the plane slugish. I agree that a short circuit in a nicad or nimh can cause a fire as well, so regardless of the type of battery there is going to be some risk. Is there insurance I can buy? someone told me the AMA insurance only covers you if you are at ama sanctioned club flying field.
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Old 06-30-2012, 07:11 PM   #6
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If there was no crash (ever) to the battery or EVER dropped and you are SURE it was the battery, not the ESC, that went up in flame FIRST....then it was a aberration.
My bet would be the ESC. You did not mention a brand. Some are pretty cheesy.

This statement make me think ESC:
[there was a loud pop, the canopy blew apart and a trail of smoke, no response from the controls]. A lipo that blew a single cell still could have adequate voltage to run the ESC IF the wiring was intact. A blown ESC would likely not function at all.

ANY dropping on a hard surface or crash of a lipo can cause damage that may not be seen but can bite you later. Usually not and folks get away with it all the time but when it bites YOU, it's a different story.

Sometimes shorts happen to the wiring inside the case. Pulling on wires, crappy wires (unfortunately WAY too common on the balance taps) or just lack of quality can do that.

Soldering together consumer grade AA will get you nowhere. They don't have enough output-internal resistance is too high.

Either get some A123 LiFe packs or decent NiMh from somewhere like:
http://www.cheapbatterypacks.com/

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Old 06-30-2012, 07:23 PM   #7
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Yep, it's far more likely that the ESC went up first. What was the state of the ESC when recovered?

Also, it's not a good idea to surround a battery with foam, it really needs air circulation around it for cooling. Same goes for the ESC but more so.. did it have good cooling airflow.
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Old 06-30-2012, 07:45 PM   #8
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The Wild Hawk/Bixler/EZ Star/Sky Surfer all have poor cooling. The draw on the battery is so low it should not be much of a concern for battery heat.
A hot ESC is more likely.

Another question-during the crash is it likely or possible that the crash itself caused battery damage or puncture? That certainly might make a lipo fire.

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Old 06-30-2012, 07:59 PM   #9
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The ESC is made by HURC, not sure how it ranks as to to quality. it is still functional and I used it when I tested the the current draw of the motor a few days after the crash. the the lipo cells are in series , wouldnt that cause a open circuit if I lost a cell? the nimh I am using are tabbed 10c 2000mah from all-battery.com they performed much better than the 1800mah that came with the wild hawk from harbor frieght. I switched out the brushmotor esc and went to brushless so I still had some of these cells left over and just added them to a pack I had previoulsy built. they perform fine, just heavy. , I have been buying stuff from headsuprc dont know the quality of the parts but they have been great with customer support. I stratch built a goldberg jr falcon electric and a jr skylark with twin electric motors . Headsuprc did all the calculations for me and let me know what parts I needed to buy. I am pretty new to RC, flew control line when I was a kid. actually enjoy building more than flying. may get around to flying the goldberg planes when my skills improve. anyway back to my question what are the better brands of batteries, esc's and motors ?. is there liability insurance I can buy? think I want to stay with lipo's just want to minimize the risk.
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Old 06-30-2012, 08:10 PM   #10
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Originally Posted by flydiver View Post
The Wild Hawk/Bixler/EZ Star/Sky Surfer all have poor cooling. The draw on the battery is so low it should not be much of a concern for battery heat.
A hot ESC is more likely.

Another question-during the crash is it likely or possible that the crash itself caused battery damage or puncture? That certainly might make a lipo fire.
actually the plane is intact, except of the canopy and some burnt foam it hit pretty soft. the esc isnt melted , doesnt smell burnt or even discolored. since you mention cooling, I think I will surface mount the esc next time so it gets some airflow. bought several spare wings and fuselages from harbor frieght. really inexpensive way to keep flying.
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Old 06-30-2012, 08:47 PM   #11
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Originally Posted by rocco61 View Post
I take it that if I do everthing right and dont use damaged batteries, this would be extemely unlikely to happpen again ?
When you ground check everything big failures are very rare.

Originally Posted by rocco61 View Post
I put together a 10c 2000mah nimh pack last night from AA cells and tried it out this morning. 3oz heavier , really makes the plane slugish.
AA cells are crap for our use - they just can't dish out the power as you are finding.

Originally Posted by rocco61 View Post
what batteries are you guys using?
The vast majority of us use LiPo's. The rest use LiFe. Very few use NiMh anymore.

Originally Posted by rocco61 View Post
Is there insurance I can buy?
Are you a homeowner? That likely covers you. Not sure about a fire however.

Originally Posted by rocco61 View Post
someone told me the AMA insurance only covers you if you are at ama sanctioned club flying field.
That someone was 100% WRONG. And there is no such thing as a sanctioned club flying field. Sanctions are for events. Clubs may also be covered by AMA as can land owners.

AMA coverage manages you wherever you fly - as long as you are abiding by the AMA safety guidelines.

Mike
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Old 06-30-2012, 08:50 PM   #12
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It does sound like it was a bad cell that was the problem, you are right in that for series cells one cell going 'open circuit would cause the voltage of the battery to go to zero. If the ESC is still working then that obviously wasn't the cause of the initial problem.
This is a very unusual occurrence, don't let it put you off LiPo's, just buy decent quality ones and mount where they will get some cooling.
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Old 06-30-2012, 09:12 PM   #13
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Are you a homeowner? That likely covers you. Not sure about a fire however.



That someone was 100% WRONG. And there is no such thing as a sanctioned club flying field. Sanctions are for events. Clubs may also be covered by AMA as can land owners.

AMA coverage manages you wherever you fly - as long as you are abiding by the AMA safety guidelines.

Mike[/QUOTE]


thanks for the information Mike, Yes I am a homeowner, I did call my homeowers insurance, they didnt know. My renewal is this month will shop around with that question in mind. the AMA insurance sounds like a good deal. enventually hope to join a local club ,that has a flying field nearby, they are really heavy on membership though , place is really busy most of the time.

thanks for the link flydiver, the thunderpower brand on that site checks out to be a good option.
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Old 07-01-2012, 01:11 AM   #14
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Originally Posted by rocco61 View Post
Have been running a Emax 2836-24 inrunner , 11.1v 2200mah 30C EZ Flite
Lipo Battery 6x3 prop and a 30amp ESC
in a wild hawk airplane. Always charged the battery at 2amps and
balanced it frequently. I live on 5 acres and fly over adjacent
vacant parcels that have a lot of dry grass this time of year. A few
days ago the front of the plane exploded and caught fire. The plane
crashed in dry grass about a 100 yards away. Fastest 100 yard dash I
think I ever ran. I was able to get the fire out before it turned
into the unthinkable. I had heard that lipo batteries could catch
fire if damaged or charged improperly. This one however just blew up,
one cell burnt up completely while the other two cells appear to be
undamaged, not even swollen . the battery had approximately 50 cycles
on it. I have talked to several of my friends , none of them have
ever had a lipo failure like this, they say usually the batteries will
puff up a bit when something is wrong and at that point they replace
the battery. I would like to continue to fly at home through the
summer , I am seriously considering going to nimh till the end of
the fire season at least. Did a search on EZ-Flite batteries didnt much on them.
Anyway I am looking for recomendations on lipo batteries. a brand that is least
likely to have any problems.
Another heavier, physically larger option is those 2300 Mah A123 cells. You would need four of them to match the 11 volts of your LiPo. These cells can not ignite and catch fire. I screwed up several years ago, and charged a two cell A123 pack with my power supply set to 3 Amps. And the voltage set to 15 Volts DC. Those cells just blew off the covers, with absolutely zero fire. Just a lot of carbon dust to clean up. Five years ago, I shorted a 6S2P A123 pack out, burned a hole right through one cell's aluminum casing. Zero fire, but ruined one cell in the process. Sounded like my 180 Amp Arc welder.

You can buy ready to go A123 packs, but to save a bit of $$$$, check out http://www.voltmanbatteries.com/serv...1-dsh-A/Detail. Both many club members, and I have ordered from voltmanbatteries, and had zero problems.

Wiring these up is not a real problem, if you've got the proper equipment. These cells put out about 2.8 Volts DC at about 30 Amps. They weigh in at about 2.6 ounces each cell. You can store them fully charged, half charged, don't seem to matter much.

They don't seem to wear out. I've got some with over 300 flights on them, and they actually improved a few percent in performance. They can also be charged at what ever current your charger will put out. I'm charging my cells at 7.5 Amps.

For my giant Big Stick, I'm charging the 12S2P A123 pack as a 6S4P pack, charging current is 30 Amps. The charger is a Cellpro Powerlab 8. Recharging time for all my A123 packs is about 17-18 minutes. Maximum current on that Giant Big Sticks Hacker A60-16M motor is about 75 Amps. With this, those A123 cells only get slightly warm, perhaps 15 degrees above ambient temperature. I've actually had these cells sitting in the sun on a hot day, and found the cells cooled off during and after a flight.

These A123 cells will never match a quality LiPo battery in regard to weight and power output, but they can be safer to operate. Generally, the equivalent A123 pack will weigh about 140% of a LiPo with the same Mah and watts output.

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Old 07-01-2012, 01:54 AM   #15
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EZ-Flight from HeadsUp? Funny you should mention it, since I had a bit of an episode (albeit not nearly as dramatic) with an EZ-Flight battery. I was flying my 3DHS Edge 41" the other day. The usual stuff: Some crappy harriers and hovers and the occasional wall and spin. Towards the end of the flight, I felt some loss of power, so I landed without incident. When I disconnected the battery, it was almost too hot to touch and very puffed. Now, this is a 30C 1800mAh battery, and my motor pulls 400W, so 1,8*30 = 54A max amp draw is definitely more than the 400/11.1=36A my motor asks for on WOT.

Conclusion: Something was definitely seriously wrong with that battery. A little hotter and something unpleasant might have happened.

Coincidence? Maybe, but I won't putting my EZ-Flight batteries through any hard attempts at 3D flying anymore.

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Old 07-01-2012, 02:48 AM   #16
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Originally Posted by rcers View Post
AA cells are crap for our use - they just can't dish out the power as you are finding.
Yup
Last year, I did some checking on a club members 5 cell 2700 Mah "AA" Nih battery pack. He was using in in a $$$$ wet turbine model as the receiver battery. BIG NO NO!

All his servos can pull a measured 14 amps peak current when moving all the transmitter sticks. (That 14 Amps peak current was measured with a $350 Fluke 87V meter with the one millisecond peak reading feature) At 14 Amps, those "AA" batteries dropped below 3.6 Volts DC in less than a second.

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Old 07-01-2012, 06:09 AM   #17
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Yes, NJSwede, I got the EZ-Flite batteries from headsuprc. Jeff at headsup is a really nice guy, helped me a lot with sizing motors, esc's and batteries. I'm not knocking the batteries he sells, but yeah a bad experience definately changes the way you look at product.

thanks for the info Kyle, will look into a123 packs , definately a much safer option. I just joined this group yesterday, wow lots a help and information from everyone , I do appreciate it .

thanks, Robert
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Old 07-01-2012, 06:29 AM   #18
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Originally Posted by rocco61 View Post
Yes, NJSwede, I got the EZ-Flite batteries from headsuprc. Jeff at headsup is a really nice guy, helped me a lot with sizing motors, esc's and batteries. I'm not knocking the batteries he sells, but yeah a bad experience definately changes the way you look at product.

thanks for the info Kyle, will look into a123 packs , definately a much safer option. I just joined this group yesterday, wow lots a help and information from everyone , I do appreciate it .

thanks, Robert
No problem, let us know how it all works out.

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Old 07-01-2012, 08:35 AM   #19
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Originally Posted by rocco61 View Post
will look into a123 packs , definately a much safer option.
Robert,

I'd argue on the 'much safer' point. Yes, without a doubt A123 are more robust and remove the small risk of fire carried by LiPos. However the risk of serious fire is incredibly small; there are many hundreds of thousands of LiPos on use in model planes (maybe millions?) and to my best knowledge there has never been a serious fire caused by one. A few models have been lost for sure, but usually that was because the model crashed and the Lipo was damaged on impact. Most times with LiPos even if they are damaged nothing happens. There was one house fire that was reported a while back that was initially blamed on a Lipo under charge but turns out that it was caused by the totally unsuitable power supply the guy was using to power his charger, it could have been any battery (yes even an A123) he was charging and the result would have been the same.

I think you have been very unlucky to have one fail in that way so soon but that doesn't mean it will happen again.

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Old 07-01-2012, 02:53 PM   #20
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The A123 being promoted are the size of regular 'D' cells. OK for larger planes but not nearly so much for smaller ones. I seriously doubt they are a candidated for your application.
They do make (made?) an 1100mA 'VPX' cell, about the size of AA. That would work but be less capacity. I've used them, they are 'OK', no great shake, better than NiMh buy a decent margin but not as good as modern lipos.

One way or another you are gaining weight and giving up something if you abandon lipos. There's a reason they are so popular.
HobbyKing is selling LiFe packs...I've no personal experience with them but some folks might. Or, just get a couple and find out.

Since the ESC still works that pretty much rules that out. So you must have gotten a battery that was either defective or 'went bad' for some unknown reason like a short from a broken wire. Unlike NJSwede you should not have been working your lipo anywhere near capacity.

My take at this point is about the same Steve above, an unfortunate and scary fluke. Very low probability of happening again. I've had buddies hand me a half dozen 2200 lipos commenting that they wouldn't charge and maybe I could do something with them. They were mashed, bashed, punctured, and generally seriously abused. No fire, no hint of a fire.

In terms of battery quality...well, that's a WHOLE different can of worms, a moving target, and no end of discussion on this forum. The ability to NOT burst into flames is generally not the main topics though. So, good luck there.
Note-I haven't bought a lipo in 2 years so I'm definitely not qualified to weigh in.

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Old 07-01-2012, 03:19 PM   #21
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Originally Posted by JetPlaneFlyer View Post
Robert,

I'd argue on the 'much safer' point. Yes, without a doubt A123 are more robust and remove the small risk of fire carried by LiPos. However the risk of serious fire is incredibly small; there are many hundreds of thousands of LiPos on use in model planes (maybe millions?) and to my best knowledge there has never been a serious fire caused by one. A few models have been lost for sure, but usually that was because the model crashed and the Lipo was damaged on impact. Most times with LiPos even if they are damaged nothing happens. There was one house fire that was reported a while back that was initially blamed on a Lipo under charge but turns out that it was caused by the totally unsuitable power supply the guy was using to power his charger, it could have been any battery (yes even an A123) he was charging and the result would have been the same.

I think you have been very unlucky to have one fail in that way so soon but that doesn't mean it will happen again.

Steve
A few weeks ago, a local club had an Electric Fun Fly. One of the military type models got tail ended in flight, and went in. The two 5000 Mah 6S batteries ignited, and burned for some 15 minutes. Nothing, even sand could put it out. After the fire, not much was left. Fires in these electric models are very rare, but in a flying site surounded by tinder dry grass or brush, even one fire might make the local TV news. Or worse.

We've also had one or two LiPo fires at our club in crashed models over the past few years.

That model crashed into a gravel road, missing a very dry giant brush pile by no more than 100 feet. If that pile had ignited, it might still be burning today.

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Old 07-01-2012, 03:55 PM   #22
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Kyle,

I appreciate that it's not unknown for a model to be lost to a LiPo fire, but usually that is as result of a crash, as was the one you mention. I'm unaware of any LiPo fire that has escalated and caused any further damage other than to the model... that's what I was referring to in my last post.
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Old 07-01-2012, 07:55 PM   #23
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I get that it is extremely unlikely that I will ever have a lipo fire again unless it is the result of a crash and yes I will probably use them again in small planes. I am going to stick with some of the more popular brands that document their quality standards . the best battery discussion as Flydiver mentions is a can of worms. not going to go there.lol thats like discussing the best engine oil in a harley forum. the A123 batteries look like a good candidate for bigger plane .I think I am ready for something aerobatic. I have plans for size .25 stik think I will give them a try in that. comfortable enough now with the wild hawk, (havent wrecked one in several months).yesterday I extended the nose on one and moved a 1300mah lipo forward to get the CG right. flys much better than it did with the 2200 just not as long. kept it in close, not near the weeds. yes I am paraniod. I dont leave my laptop plugged into the charger either since a dell with a defective battery burned down my coworkers house a few years ago.
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Old 07-02-2012, 02:14 AM   #24
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Originally Posted by JetPlaneFlyer View Post
Kyle,

I appreciate that it's not unknown for a model to be lost to a LiPo fire, but usually that is as result of a crash, as was the one you mention. I'm unaware of any LiPo fire that has escalated and caused any further damage other than to the model... that's what I was referring to in my last post.
We've had three club members that have had fires inside their homes because of LiPo fires. This was several years ago before the new modern chargers that balance while charging and so on.

A club member just picked up the Cellpro 10xp charger last week. Used it to charge his two cell LiFe receiver battery, the 10xp charger flagged an error. The total voltage on the balance cable didn't match the voltage on the power leads. Yup, the battery power connector was intermittent. He was going to fly a 30 cc gasser with it next day, that Cellpro charger likely saved an airplane.

Nice. Seems that fires during the charging process really dropped off, once we got chargers that monitor everything during the charging process.

But, as has been pointed out in this thread, some areas of the USA have real fire risks because of the tinder dry conditions in these areas. I'd hate to have a model go in, and start a grass fire. In the Milwaukee area, one TV stations showed a local fire chief dropping a 4th July sparkler into a very dry lawn. The grass was about 3 inches high. The lawn ignited, and burned a circle two feet in diameter within 5 or 10 seconds.

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