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Old 07-04-2014, 01:01 PM   #31
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Originally Posted by frozenpod View Post
Lipo IR reduces as temperature increases within the operating temperature range.

Hence why people use warming pads higher charge rates ect to warm the cells.
The last big race I went to, they were checking battery temps. You are not allowed to heat your packs.

ROAR rule governing warming packs:

8.3.2.5.4: Maximum temperature for a charged li-poly battery pack shall be ambient temperature +/-5 deg.

Nobody in their right mind would intentionally build a bad, high resistance LiPo so it would warm itself under load.
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Old 07-04-2014, 03:30 PM   #32
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I don't think it's the high charge rate that's heating up the pack. It's the high discharge before the charge. The high charge rate is used to "keep the heat" in the pack before it has time to cool down from the high discharge. That's why it has to be perfectly timed before your race starts, otherwise the pack cools down and you loose the bennifit of a heated pack.
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Old 07-04-2014, 04:47 PM   #33
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If the battery is six degrees over ambient, you are disqualified.
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Old 07-04-2014, 05:20 PM   #34
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From the little experience I have: lighter (low MAH) packs for mod and small tracks, Lager MAH packs for Blinky 17.5, 13.5, 21.5, 25.5 big tracks with long full throttle back straights. C ratings to me differ from company to company pack to pack. I had a 20c turnigy 5000 mah that I swear it had more punch than my SMC 6500mah 70c (or maybe it was just lighter).
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Old 07-05-2014, 02:19 AM   #35
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Not everyone on this forum runs under all roar regs.

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Nobody in their right mind would intentionally build a bad, high resistance LiPo so it would warm itself under load.
No they wouldn't, not sure why you would suggest the idea?
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Old 07-05-2014, 02:21 AM   #36
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I don't think it's the high charge rate that's heating up the pack. It's the high discharge before the charge. The high charge rate is used to "keep the heat" in the pack before it has time to cool down from the high discharge. That's why it has to be perfectly timed before your race starts, otherwise the pack cools down and you loose the bennifit of a heated pack.

Both can increase the temperature of the pack. Some people are charging at 40A and it certainly increase the temp.
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Old 07-05-2014, 02:26 AM   #37
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100% right !!!! That would also mean that the lower capacity packs would heat up more when the the max amp charge rate has been fixed by the event officials...I see that most events limit everyone to a 14 amp max charge rate, which will not heat up a 7600mah pack, but will crank the heat in a 2700mah/3300mah pack.....
Depends on the IR of the pack. A low grade lipo even if warm will still not be as good as a high end lipo.
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Old 07-05-2014, 04:25 AM   #38
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My car weighs in at 1170g without a battery, would using a 300g battery still be wise (orca 6200mah 90c). I don't need the most competitive car, but I would still like to be able to compete
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Old 07-05-2014, 05:19 AM   #39
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Firstly the Orca 6200 90C is a rebranded IP 6000 90C, great battery.

Which car is it, why is your car 1170g, which shell LW ect?

Given the weight of your car I would suggest using the lightest battery that balances your car with no extra weight.
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Old 07-05-2014, 05:36 AM   #40
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The car is a TB04 pro V2 it weighs 1096g without body or battery, I just assumed a lightweight protoform shell is about 70g, hence the 1170g.

It just so happens that a 300g battery will balance my car left to right.
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Old 07-05-2014, 05:47 AM   #41
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There are a number of batteries that are around 5700-6200mAhr that are around 295g that should work for you.

The last 3 LW shells I have had weigh 87-90g.
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Old 07-05-2014, 06:01 AM   #42
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Quote:
Originally Posted by frozenpod View Post
There are a number of batteries that are around 5700-6200mAhr that are around 295g that should work for you.

The last 3 LW shells I have had weigh 87-90g.
My guess was a bit off then, going to have to look for weight saving in other places too then.

The lhs sells the orca 6200mah 90c so I think that's the route I'll choose
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Old 07-05-2014, 07:20 AM   #43
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My guess was a bit off then, going to have to look for weight saving in other places too then.

The lhs sells the orca 6200mah 90c so I think that's the route I'll choose
I depends how many stickers and paint you cake on your body. If you paint them lightly and only use a couple stickers you can achieve 65 gram bodies.
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Old 07-05-2014, 07:48 AM   #44
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65g wow. Which body?
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Old 07-05-2014, 08:17 AM   #45
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65g wow. Which body?
Protoform lw Mazda speed 6. I've got the ltc-r lw down to 70 as well.
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