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Old 01-16-2009, 12:31 PM   #16
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Shawn, the voltage rule should be changed (for a 2 cell pack) to 8.40 volts max, not the 8.40 +/- .04 volts. Now you have everyone charging to 8.44 volts. Let's stop the nonsense and make it 8.40 volts max.
I agree, the jokers at CE are even encouraging this behavior by modifying their chargers to make it easy. Oh, right, it's to allow it to be "adjustable" in case you've got a bad volt meter. Whatever.
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Old 01-16-2009, 02:32 PM   #17
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Dont see it bieng a hassle unless you leave your car standing static on the hot surface for a long time.
The track temp can be 60 deg/c but wont lend to the pack being teh same temp.

So dont worry you wont have any issues with it unless you negligent with your charging and discharging.
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The December meeting at CMCC was extreme! The track temp actually reached 64C ... brushless systems were thermalling and rollouts had to be dropped ... 5 minutes track time over a surface @ 64C + sitting on the grid until XYZ sorts out his xtal problems

I think my telemetry temp sensor is going on my battery and not on my motor!
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Old 01-16-2009, 02:44 PM   #18
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Any pack heating should be banned! Otherwise it becomes an enforcment nightmare.
Pack heating - what if someone stores his batteries inside his cab with the heater on? Ambient temp inside the cab much greater than outside @ this time of year in the USA ... would this be classed as 'pack heating'?
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Old 01-16-2009, 03:01 PM   #19
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I agree, the jokers at CE are even encouraging this behavior by modifying their chargers to make it easy. Oh, right, it's to allow it to be "adjustable" in case you've got a bad volt meter. Whatever.
As a note, my bantom charger was only charging to 8.32, which was a noticeable difference from the 8.40 I was getting with my CE (oval racing). It'd be nice to calibrate it to my liking (reality).

I'd also much rather the jokers who try to push the .5% tolerance doing it in an automatically cut off Lipo mode than Nimh mode wher they can forget to cut it off and burn down the hobby shop.

Basically, being able to calibrate your charger isn't a bad thing.
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Old 01-16-2009, 03:32 PM   #20
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As a note, my bantom charger was only charging to 8.32, which was a noticeable difference from the 8.40 I was getting with my CE (oval racing). It'd be nice to calibrate it to my liking (reality).

I'd also much rather the jokers who try to push the .5% tolerance doing it in an automatically cut off Lipo mode than Nimh mode wher they can forget to cut it off and burn down the hobby shop.

Basically, being able to calibrate your charger isn't a bad thing.
That's a good point. I guess the jokers are the guys that "calibrate" them to charge to 8.44 rather than 8.40, 'cause the rules say you can. That's a pretty sketchy way to use the most accurate charger on the market. If anybody should get to 8.40 every time, it's them. The +/- was put in there for people with chargers that aren't as accurate, and now it's being abused by guys that think .04 is more important than the safety of you, me, and the places we race. I can't think of anything nice to say about that.
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Old 01-16-2009, 04:39 PM   #21
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I suppose another consideration is whether or not you really want to use a charger that's so far off with its voltage sensing. It could be a sign of damage, or poor quality control by the manufacturer.
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Old 01-16-2009, 05:07 PM   #22
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Originally Posted by jiml View Post
Shawn, the voltage rule should be changed (for a 2 cell pack) to 8.40 volts max, not the 8.40 +/- .04 volts. Now you have everyone charging to 8.44 volts. Let's stop the nonsense and make it 8.40 volts max.

Any pack heating should be banned! Otherwise it becomes an enforcment nightmare.

And where did you get a ROAR hat???
I understand what your saying but without any tampering when I balance charge my SMC 4000 packs at 1C and they finish the charge @ 8.42 - 8.44. I use a Hyperion charger...so...I thought 8.44 was what lipos peak at normally??
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Old 01-16-2009, 05:33 PM   #23
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I have yet to see/read about a LiPo that says to charge it outside of 4.2 volts per cell, which is 8.4 volts.

When was the last time you balanced the pack?
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Old 01-16-2009, 05:53 PM   #24
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Are people using tire warmers or hair driers? I don't see any of this at our track. How are they warming them.?
And to my knowledge I thought some manufacturers were actually presetting chargers to peak at 8.44 and it was safe. And then a rule was determined. If its safe and you can afford a 50 cycle pack why worry. At what point is over charging not safe.? 9v 10v?. If .4 is pushing the pack then maybe we are to close now. I saw an Orion pack bulge till 18v before it blew up.
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Old 01-16-2009, 06:19 PM   #25
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If nobody is allowed to heat the packs then we are all on the same level. If everyone heats there packs we are all on the same level. Wouldn't it just be easier, safer, and smarter to all be on the same level that doesn't burn down the RC tracks?
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Old 01-16-2009, 06:25 PM   #26
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If nobody is allowed to heat the packs then we are all on the same level. If everyone heats there packs we are all on the same level. Wouldn't it just be easier, safer, and smarter to all be on the same level that doesn't burn down the RC tracks?
+1 but if .4 is of no consequence either way whats the big deal? If someone thinks .2 millionths of a boost costing 350 cycles is going to help who cares. And if .4 is a safety issue then there is no room for error. I'm curious as to know what the concern is and at what magnitude. This topic was foreseen when the lipo revolution started and here we are.
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Old 01-16-2009, 06:28 PM   #27
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If nobody is allowed to heat the packs then we are all on the same level. If everyone heats there packs we are all on the same level. Wouldn't it just be easier, safer, and smarter to all be on the same level that doesn't burn down the RC tracks?
Pack heating notwithstanding, being on the same level defies all rules of a competitive racer's logic. I'm just sayin'!
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Old 01-16-2009, 07:12 PM   #28
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I have yet to see/read about a LiPo that says to charge it outside of 4.2 volts per cell, which is 8.4 volts.

When was the last time you balanced the pack?
I balance about every few weeks or so...I balanced them last week. I have had these for several months.

I checked Kokam's site and they list the voltage for their lipos @ 4.2V +/- 0.03V. I don't believe in overcharging, but if charged properly I believe the packs will peak within +/- 0.04V of 4.2V...at least that's the way I understand it.
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Old 01-16-2009, 07:21 PM   #29
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That's kind of odd, actually...
I could see that voltage peaking if it wasn't quite balanced...

But if there's been no issues, I don't think it'll cause a problem
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Old 01-16-2009, 09:47 PM   #30
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I agree, the jokers at CE are even encouraging this behavior by modifying their chargers to make it easy. Oh, right, it's to allow it to be "adjustable" in case you've got a bad volt meter. Whatever.
CE are not jokers they are selling what racers want to buy. If a racer can't get his CE charger to go to 8.44 he can get an LRP charger that can be calibrated to go up to 8.44

18 months or so ago I said when racers start using Lipos you will see how this technology isn't as perfect as everyone claims it to be. Now that it's being used by the racers what I said at that time is has come through. At that time I was accused of propaganda to save my matching business.
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