20C vs. 40C Watts at same discharge rate? - RC Groups
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Feb 25, 2010, 06:37 PM
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20C vs. 40C Watts at same discharge rate?

Given three exact batteries except the C rating...

1800mAh 4S Lipo Pack 20C
Constant Discharge: 20C (36A)
Peak Discharge (10sec): 30C (54A)

1800mAh 4S Lipo Pack 30C
Constant Discharge: 30C (54A)
Peak Discharge (10sec): 40C (72A)

1800mAh 4S Lipo Pack 40C
Constant Discharge: 40C (72A)
Peak Discharge (10sec): 50C (90A)

With the same discharge rate of 36Amp for each pack, would the 40C pack hold its Voltage better and offer higher Wattage?
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Feb 25, 2010, 07:44 PM
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write2dgray's Avatar
Theoretically, yes .
Feb 25, 2010, 07:59 PM
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Challenger 413's Avatar
Adding to that...Depends a lot on the cells and if they can hold voltage under a load. It could be that a 25C pack that is better made (better cells) can hold higher volts under a load than a cheaper 40C pack...

Feb 25, 2010, 09:04 PM
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earlwb's Avatar
Also if the packs C rating is correct, then the 40C pack won't get as warm as a 20C pack would at the same discharge rate. The 40C battery is supposed to have less internal resistance than a 20C pack.
Feb 26, 2010, 12:28 AM
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Himalaya's Avatar
using acurately rated(neither over nor under rating) 40C and 20C packs:

at 20C discharge, you get roughly 5.6% more voltage and 11% more power from the 40C pack.

at 40C bursts, you get 12.5% more voltage and 26.6% more power from the 40C pack.
at 5C mild discharge, you get 1.3% more volts and 2.6% more power from the 40C pack.

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