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Old 08-17-2008, 11:22 AM   #16
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Originally Posted by CarbonJoe View Post
Do you use one for your cell phone? Laptop? iPod? All 3 of them use LiPo batteries...

Why not require them for NiMH as well, which don't burn, but explode.
Sure don't, but then again all of those devices have electronic protection to keep from using them in a unsafe manner and are never subjected to the amp loads RC requires.

also my cell phone, laptop and ipod use a lithium ion battery.
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Old 08-17-2008, 11:28 AM   #17
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Originally Posted by CarbonJoe View Post
Do you use one for your cell phone? Laptop? iPod? All 3 of them use LiPo batteries...

Why not require them for NiMH as well, which don't burn, but explode.
if you don't get it then none of us can help you understand and you'll just have to experience it for yourself

but would i think that if the ruling bodies had had the forsight to know that manufacturer's would have pushed the capacity envelope as far as they have then we would have been forced to use some sort of bomb-proof container long ago
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Old 08-17-2008, 11:31 AM   #18
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All lithium based chemistries (except the nanophosphate A123 chemistry) have the potential for thermal runaway. There have been many documented cases of Sony and Dell laptops catching fire.

What is different between the electronic circuitry in the cell phone, laptop, or iPod that is so much better than that in a Pulsar or ICE charger? Don't they charge using the same CC-CV charging method? The thermal runaway is due to over voltage, right?
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Old 08-17-2008, 11:34 AM   #19
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aren't every cellphone charger basically a wallplug trickle charge type of unit, whereas all the RC-based chargers are going at a much higher amperage rating?
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Old 08-17-2008, 11:38 AM   #20
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I use one for charging and transportation.

Better safe than sorry. It's a small price to pay compared to burning down your house.
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Old 08-17-2008, 11:45 AM   #21
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if you don't get it then none of us can help you understand and you'll just have to experience it for yourself

but would i think that if the ruling bodies had had the forsight to know that manufacturer's would have pushed the capacity envelope as far as they have then we would have been forced to use some sort of bomb-proof container long ago
I've seen one LiPo fire, due to someone trying to make a last minute adjustment to a 4wd buggy, and puncture the battery with a screwdriver. It started smoking, but luckily he was able to rip the pack out of the car before it was damaged. But there is a big difference in dead shorting a pack through physical abuse causing the issue than using a Li compatible charger in a normal manner. Why doesn't ROAR also mandate use of a thermal cutoff in every charger as well?

Interestingly, the label on the bottom of the Orion 3800 states "do not charge at less than 1C or more than 2C". What's up with the less than part?

How many LiPo charging fires have there been? Maybe the airplane guys can help with this one, as they have been using LiPo a lot longer than car guys have. Almost every large race has had reports of NiMH packs blowing up. Heck, even certain NiMH packs were banned for a while in Europe for this specific reason.
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Old 08-17-2008, 11:55 AM   #22
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are you asking a specific question or just stirring the pot ?
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Old 08-17-2008, 12:01 PM   #23
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I keep a sack in my pants..

Hot stuff ...
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Old 08-17-2008, 01:17 PM   #24
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Quote:
Originally Posted by ratherBracin View Post
are you asking a specific question or just stirring the pot ?
A specific question... other than the YouTube videos where people purposely destroy a LiPo pack by cooking them with overvoltage, are there any documented examples of LiPo fires specifically from following recommended charging practices? Just playing the part of the sceptic. Given the big issues in Europe about some NiMH batteries being banned because of pack blow ups earlier this year, I would have expected so see the same stories for LiPo.

Even for off-road nitro, I would have expected to see stories about LiPo Rx packs flaming up, given the close proximity to 250 degree .21 buggy engines, especially in hour long mains. Not much air flow inside a sealed battery box under a lexan body. Look at where the XRAY battery compartment is in relation to the engine.

If it eases your mind to charge in a "bunker", save yourself some money and get a surplus 50 cal ammo box for less than $10.
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Old 08-17-2008, 01:42 PM   #25
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I have a lipo sack and use it when I charge, as well as to store the batteries when they aren't in use. It's just a precautionary thing, I treat them right and charge them correctly, so they shouldn't have any issues...but you just never know. When you're dealing with combustible chemicals, it's better to be safe than sorry. Same as wearing safety goggles in a lab or anything like that. Accidents happen.
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Old 08-17-2008, 03:08 PM   #26
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Quote:
Originally Posted by CarbonJoe View Post
All lithium based chemistries (except the nanophosphate A123 chemistry) have the potential for thermal runaway. There have been many documented cases of Sony and Dell laptops catching fire.

What is different between the electronic circuitry in the cell phone, laptop, or iPod that is so much better than that in a Pulsar or ICE charger? Don't they charge using the same CC-CV charging method? The thermal runaway is due to over voltage, right?
Almost all household lipo chargers (Laptop, cell phone, ect...) cut off when the pack reaches 4.2V per cell. They do not keeep charging the last 10% that our hobby chargers can. Thermal runaway can also be caused by physical damage shorting out the internals.

Quote:
Originally Posted by ratherBracin View Post
aren't every cellphone charger basically a wallplug trickle charge type of unit, whereas all the RC-based chargers are going at a much higher amperage rating?
Cell phone as ,most other household chargers are not really chargers they are just power supplies. The charger is built into the unit. I would guess that most are able to charge close to the 1C rating and a cell phone pack is pretty small.

Quote:
Originally Posted by CarbonJoe View Post
I've seen one LiPo fire, due to someone trying to make a last minute adjustment to a 4wd buggy, and puncture the battery with a screwdriver. It started smoking, but luckily he was able to rip the pack out of the car before it was damaged. But there is a big difference in dead shorting a pack through physical abuse causing the issue than using a Li compatible charger in a normal manner. Why doesn't ROAR also mandate use of a thermal cutoff in every charger as well?

Interestingly, the label on the bottom of the Orion 3800 states "do not charge at less than 1C or more than 2C". What's up with the less than part?

How many LiPo charging fires have there been? Maybe the airplane guys can help with this one, as they have been using LiPo a lot longer than car guys have. Almost every large race has had reports of NiMH packs blowing up. Heck, even certain NiMH packs were banned for a while in Europe for this specific reason.
I agree I have had more than 10 packs puff up on me but only one fire (That I didn't cause for my own pleasure) almost all have been from charging a damaged pack. I have had a couple puff for no real known reason. One pack was a brand new brand name pack the other a pack only used a couple times, also from a well known manufacturer. Both during charging and I caught them before anthing bad happened. (Also all happened to be airplane packs, IE no hard case)

I would guess that orion states that because most good lipo chargers have a time cutoff and if you charge at .5C it will timeout before it is done.

I also agree about the NiMH packs if I was running the cells that everyone has been having trouble with I would put them in something. I have to say though in 25+ years of racing I have only seen one pack explode and it was a NiCd 20 years ago.


Quote:
Originally Posted by CarbonJoe View Post
A specific question... other than the YouTube videos where people purposely destroy a LiPo pack by cooking them with overvoltage, are there any documented examples of LiPo fires specifically from following recommended charging practices? Just playing the part of the sceptic. Given the big issues in Europe about some NiMH batteries being banned because of pack blow ups earlier this year, I would have expected so see the same stories for LiPo.

Even for off-road nitro, I would have expected to see stories about LiPo Rx packs flaming up, given the close proximity to 250 degree .21 buggy engines, especially in hour long mains. Not much air flow inside a sealed battery box under a lexan body. Look at where the XRAY battery compartment is in relation to the engine.

If it eases your mind to charge in a "bunker", save yourself some money and get a surplus 50 cal ammo box for less than $10.
I don't think there are many fires from undamaged packs being charged correctly but at the track the ones I have seen have been from racers charging in the wrong mode, such as NiMH mode for a Lipo. That is when a battery bunker comes in, in my opinion. Just a saftey precaution for idiots and us that try charging damaged packs.

another thing industrial lipos, such as used in houshold devices are made to be much more tolerant of our abuse, be it heat, physical damage or overcharging, their trade off is that they can't supply the kind of amps at the low weight we demand.

That is also why some companies have better lipos than others, they can be made to take more than 4.2V per cell and many of the top brands can, that is why sanctioning bodies have put in place voltage rules. To keep guys from pushing the limits.

In closing, I have been using lipos for 5 years now and my problems with them have gone down every year, companies make better cell and better chargers. I saw a real drop when it became norm to leave 20% in the packs and balance chargers became available. If A123 systems could make cells that fit in cars and had a more normal voltage they would be selling tons with almost no chance of fire. In air they are taking over.

Lockhart
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Old 08-17-2008, 07:16 PM   #27
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Lockhart -

Thanks for posting your experiences. It appears that most of the apparent problems are from a) physical damage to the cells (either from a crash or mfg error) b) over-discharging or c) plain old user error. Hopefully, hard shell cases and mfg quality control should take care of a) above. Unfortunately, you can't idiot proof LiPo charging with a multi type charger. They'll only make better idiots.

I too wish that A123 could make RC specific (meaning size, voltage, and capacity) cells. Their Hypersonic charger can charge them in 15 minutes and the cells are supposedly intrinsically safe. Not sure that their chemistry can achieve 4.2V per cell.

Not sure I completely agree with some charger's 4.2V cutoff. If a charger cuts off as soon as the cell hits 4.2V, then it is missing half of the recommended CC-CV charge profile. Apparently, either the Orion or LRP chargers cut off as soon as the cell hits 4.2V.

What is the definition of "fully charged" for a LiPo pack?
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Old 08-18-2008, 02:48 AM   #28
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Quote:
Originally Posted by CarbonJoe View Post
Do you use one for your cell phone? Laptop? iPod? All 3 of them use LiPo batteries...

Why not require them for NiMH as well, which don't burn, but explode.
They charge at a much much lower charge rate and they do still explode

Quote:
Originally Posted by Tubaboy View Post
cell phones & laptops use li-ion, not lipoly.

But hey, up to you, just if you ever do, please sit in the corner by yourself so you don't put another racer's equipment at risk. Our track doesn't require them for nimh's, but does recommend that our racers do. Our club's flight area requires the charging of any battery to be done in a bunk of sorts.

Cya,
Paul
My cell phone and laptop use lipoly

Quote:
Originally Posted by ratherBracin View Post
aren't every cellphone charger basically a wallplug trickle charge type of unit, whereas all the RC-based chargers are going at a much higher amperage rating?

Basically a trickle charger about 0.1 amps or less




And yes i use lipo sacks and so does my dad
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Old 08-18-2008, 03:23 AM   #29
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I use one, I charge and store my lipos in there. Better to be safe, than sorry
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Old 08-18-2008, 09:37 AM   #30
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Quote:
Originally Posted by CarbonJoe View Post
Lockhart -

Thanks for posting your experiences. It appears that most of the apparent problems are from a) physical damage to the cells (either from a crash or mfg error) b) over-discharging or c) plain old user error. Hopefully, hard shell cases and mfg quality control should take care of a) above. Unfortunately, you can't idiot proof LiPo charging with a multi type charger. They'll only make better idiots.

I too wish that A123 could make RC specific (meaning size, voltage, and capacity) cells. Their Hypersonic charger can charge them in 15 minutes and the cells are supposedly intrinsically safe. Not sure that their chemistry can achieve 4.2V per cell.

Not sure I completely agree with some charger's 4.2V cutoff. If a charger cuts off as soon as the cell hits 4.2V, then it is missing half of the recommended CC-CV charge profile. Apparently, either the Orion or LRP chargers cut off as soon as the cell hits 4.2V.

What is the definition of "fully charged" for a LiPo pack?
From the chargers I've seen it's looking at the total voltage and not cell voltage - as far as the cutoff is concerned. For example my charger can display each cell's voltage but it's looking for a total voltage of 8.4 or 12.6 for 2s and 3s packs. That's the reason for needing to keep them balanced, it's possible to have one cell at 3.9v and another at 4.4 and the charger will keep putting in amperage. Same for LVCs, as far as I know all of them only look at the total voltage, so a pack out of balance could have one cell at 3.0v and another at 3.7v and it will continue to run.

To me that's where most of the lipo danger is - not keeping a pack in balance.
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