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Old 11-08-2007, 10:46 AM   #16
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My understanding is that there are chargers that will let you go beyond the cutoff of 4.2V/cell, so you could specify something like 4.3V for example. You can charge them higher, and get more voltage. Of course, you risk causing a fire and doing severe damage to your cells... but since when has that stopped anybody? :-(

It's deeply irresponsible, and the practice should be banned with severe penalties for breaking the rule... but it's out there. And if you can count on anybody to push the envelope, it's the R/C crowd. Scary, huh?
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Old 11-08-2007, 11:02 AM   #17
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Sindrome I do not know any charger where one can do that. And if there is any, is problably old.

The choose one can do is the number of cells. Is the standard that the manufacturers adopted to avoid problems with lipos as far as I know and I am with lipos in airplanes for some years.
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Old 11-08-2007, 11:38 AM   #18
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Default charging lipo beyond 4.2v a cell

Which charger lets you charge beyond 4.2v a cell? Just because something exists doesn't mean it is a pandoras box waiting to be opened.

Have you tried to charge LIPO's to 4.3v a cell and gotten a higher voltage? Anecdotal evidence cannot be relied on to be anything but anecdotal.

Why does everyone think that LIPO will be overcharged? Why is every common sense issue disregarded because r/c racers will push the envelope? You have idiots in every activity that you can do, people who don't give a damn about safety or anyone other than themselves. Competition brings out these tendencies in people. But the simple way to stop the behavior is to do random checks of people charging batteries. If they are overcharging, they are banned. Simple as that.

In addition, if a track is so woried about overcharging LIPOs, only allow chargers that fix the voltage and the current at 1c or 2c, or whatever.

Given the current state of NIMH used in competition, quality cased lipo's are much safer. I have personally seen numerous NIMH cells blow that were being charged at 6amps. I have yet to see or hear of 1 cased LIPO catching fire, ever.
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Old 11-08-2007, 11:56 AM   #19
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Quote:
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Sindrome the only way that one can overcharge a lipo is selecting 3 cells instead of 2 in the charger isn't it?
Sorry to be quoting myself but I was trying to do this with my charger and it does not allow it. I am using a Simprop Intelli-speed charger and with a half used Trakpower lipo battery the charger won't start if I choose 3 cells, 11,1v.

So as you see this is not a expensive charger and it is protected to that type of mistake. I cannot see how can someone do to overcharge a lipo.
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Old 11-08-2007, 11:59 AM   #20
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Did you look at the pack that blew up? Its a IB cell.... it pretty much common knowledge that the last batch of IB cells has problems... thats why you cant find any at the moment... the importer sent them back to IB.
If one brand of LiPo suddenly has a problem should we ban all LiPo cells?
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Old 11-08-2007, 12:24 PM   #21
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ottoman I think the problem is not only with the IB, is mainly with IB but I have seen photos of some other brands.

The situation is that IB have tryed to allow for a superior power from their cells and they were suceded. The explosions are the price to pay. Everybody was using IB because of that superior power. If other manufacturer decide to put the some power on their cells they will have the some problem certainly. I believe it is the limit of NiMhs, nothing else.

Look that any middle range lipo will have more power that those top IB that explode, so what are people waiting to change?

Is because the rules? Change the rules.
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Old 11-08-2007, 12:33 PM   #22
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ugh.. here we go again...

flame thrower or a shotgun...
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Old 11-08-2007, 12:51 PM   #23
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adamliehr, ok the conversation will lead to nowhere. Ok.

But as least do you have a rational explanation why people where happy to move from 1500Nicad to 1700Nicads because they where more powerful and with better runtimes. People moved happily from 2400 Nicads to 3200Nimh (new chemistry) because they were more powerful and gave better runtime People moved happily from 3200NiMh to 4200Nimh because they were more powerful and gave better runtimes. And now people is not happy to move from 4200NiMh to 4900LiPo (new chemistry) because they are more powerful and give better runtimes???

I realy do not understand.
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Old 11-08-2007, 01:05 PM   #24
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How many racers have wanted the individual cell voltage pushed higher and higher even by the small steps, only to be happy to go to 5 cell which encourages the practice of getting even more out of a cell because they just gave up 1.2*** somthing volts.
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Old 11-08-2007, 01:28 PM   #25
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GP needs to get a good cell out again

I never remember hearing about gp cells blowing up.

Its always the IB cells we hear about
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Old 11-08-2007, 02:16 PM   #26
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Quote:
Originally Posted by PDM View Post
adamliehr, ok the conversation will lead to nowhere. Ok.

But as least do you have a rational explanation why people where happy to move from 1500Nicad to 1700Nicads because they where more powerful and with better runtimes. People moved happily from 2400 Nicads to 3200Nimh (new chemistry) because they were more powerful and gave better runtime People moved happily from 3200NiMh to 4200Nimh because they were more powerful and gave better runtimes. And now people is not happy to move from 4200NiMh to 4900LiPo (new chemistry) because they are more powerful and give better runtimes???

I realy do not understand.
PDM:

Whoa buddy...

This conversation will lead the same way, every other lipo vs. nimh did.... with a bunch of people pissed off and nothing ever solved.

Honestly, I could care less about which cell that we run. I'm going to run whatever the race/track tells me I can run.

Personally I have never run a lipo pack, because there have been no races/tracks that have allowed them to be run in my area. I also have never had a nimh cell blow up on me.

It's funny how worked up people get over this issue, and make themselves look foolish (not yourself in particular, but everyone is gets on here "flipping out"). Run whatever you want to run, don't run what you don't want to run.... it's that simple

When I made my previous comment, I was not bashing either side of the argument. Just makeing a somewhat truthfull joke. So please, take it as a joke.

Last edited by adamliehr; 11-08-2007 at 02:23 PM. Reason: Didn't like previous wording....
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Old 11-08-2007, 02:27 PM   #27
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...So please, take it as a joke.
No need

I just did not understand it I have to blame my bad english.

Friends as before?
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Old 11-08-2007, 03:10 PM   #28
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LOL... all good
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Old 11-08-2007, 04:34 PM   #29
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Quote:
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Which charger lets you charge beyond 4.2v a cell? Just because something exists doesn't mean it is a pandoras box waiting to be opened.
...
billjacobs - overcharging lipos is a pandora's box waiting to be opened.
Yes - overcharging will give better discharge performance.
It is also extremely unsafe. Repeated slight overcharges will make a safe cell unsafe as well as killing the cycle life tremendously. Please read the thread title "Lipo Fires 101" for a detailed explanation. A gross overcharge will destroy the cell and have a high liklihood of a fire.

Great - now that I confirmed it, there will be a ton of people who will try it.

If ROAR ever legalizes lipos, there should be a rule to prevent this. It's fairly straight forward to spot an overcharged lipo. All someone needs to do is measure the open circuit voltage with a voltmeter - it should never exceed 4.20V/cell or 8.40V as a pack.

It's quite easy to overcharge a lipo. Anybody can get a hold of an adjustable voltage benchtop power supply. You can also charge a lipo in NIMH or NICAD mode where the voltage can greatly exceed 8.40V. You can also go inside your charger and twist the little voltage calibration potentiometer so that when the charger thinks it' at 8.40V, the battery is actually at 8.60V. One of the integy chargers (which I think should be banned) even has a setting for 4.25V/cell.
The bottom line is: DON'T OVERCHARGE A LIPO....EVER.
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Old 11-08-2007, 04:34 PM   #30
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...
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Last edited by linger; 11-08-2007 at 04:35 PM. Reason: double post
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