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C rating

Old 12-23-2010, 11:35 AM
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shaf
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I have two batteries, one with a 15c rating and the other at 30c. What exactly is the c rating and can I use them interchangably? Specs are otherwise the same.

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Shaf
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Old 12-23-2010, 11:47 AM
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firemanbill
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Originally Posted by shaf View Post
I have two batteries, one with a 15c rating and the other at 30c. What exactly is the c rating and can I use them interchangably? Specs are otherwise the same.

Thanks

Shaf
The "C" rating is the rate at which you can safely draw amps out of them. The formula is MAh x C/1000 = amps.

So if you have a 2100 mah 15c battery it is

2100 x 15 = 315000/1000 = 31.5 amps

for a 30c it would be

2100 x 30 = 63000/1000 = 63 amps
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Old 12-23-2010, 12:49 PM
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cliffh
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...and yes you can use them interchangably. Depending on age, useage and other factors, you may see a slightly larger amp draw and more power with the 30C battery as the voltage will likely drop less under load.

Cliff
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Old 12-23-2010, 01:00 PM
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firemanbill
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Well you can use them interchangeably if the max amp draw is under 31.5... if it is above that then the 15c battery won't be up to the task.
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Old 12-23-2010, 02:59 PM
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Originally Posted by firemanbill View Post
Well you can use them interchangeably if the max amp draw is under 31.5... if it is above that then the 15c battery won't be up to the task.

Good catch. I never use my batteries near the max ratings, so I didn't think to mention that.

Cliff
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Old 12-23-2010, 03:02 PM
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That's a good thing to do, Always give yourself some leeway amp wise. If you are running a battery at it's maximum c rating all the time it's like driving you car everywhere with the gas mashed all the way to the floor all the time. Not too good for it.
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