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Old 12-14-2006, 12:32 PM   #1
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Default Battery question

Hi there guys,

So I was having a bit of a discussion with a few of my fellow racers and it all revolved around battery performance according to mA.

Knowing a bit about electronics I have the following opinion:

If you have a RC car that has a certain power requirement, call it x watts. If I have a battery say a 2400mA battery and the battery charged is rated at 7.2V unmatched cells. Then if I have a 3000mA battery that is also exactly rated at 7.2V, there will be no performance difference due to the current pull being the same. My understanding is that having that extra 600mA will only allow the battery to last longer than the 2400mA before it loses all power and needs to be recharged.

I understand that voltage is exponential when being discharged but is not enough to be effected in a 5 min race. If mA was so important then my understanding is that a GP4300 would be prefered over a IB4200, but that is NOT the case.

My main arguement is that our local rules allow only 2400mA batteries to be run and that allowing any range of unmatched batteries will make races very unfair. Which I completly disagree with but am open minded enough to hear the pros of RCtech prove me wrong and allow for me to get a better understanding if I have missed the boat.

Apologies about the newbie question and all info will be great!

Naut
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Old 12-14-2006, 12:43 PM   #2
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There will be a performance difference between cells of different capacity due to the internal resistance of the cells.
The higher capacity and newer nimh cells have lower IR than previous versions. This means more V at the motor and more speed/punch as a result.
Basically less of the charge is wasted as heat.
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Old 12-14-2006, 01:06 PM   #3
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Quote:
Originally Posted by loopedeloop
There will be a performance difference between cells of different capacity due to the internal resistance of the cells.
The higher capacity and newer nimh cells have lower IR than previous versions. This means more V at the motor and more speed/punch as a result.
Basically less of the charge is wasted as heat.
I understand why having an internal resistance difference will make a difference. However what happens if I came across a pack that has a better lower internal resistance than the higher mA pack? Surely then the lower mA pack will be better?
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Old 12-14-2006, 01:14 PM   #4
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Umm generally yes.

We use nicds in NZ for stock. The limit is 1500mah.
Most drivers tend to prefer sanyo 1300's as they have more punch, even though they have a lesser capacity.
This is due to the lower IR compared to say tamiya 1400's.

You see what I mean?
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