Li-Po amps question for a Top speed car
02-23-2006, 08:46 AM
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Li-Po amps question for a Top speed car
Hi Guys-
I am building a Associated 1/10th scale RC10L pan car as a project. The goal is the 90 mph range. The original plan was 16-18 "C" NIMH cells for a total of 20ish volts, a Lehner 2800XL or 3100XL brushless motor, anda BK WARRIOR 9920 speed control.
After talking to a experienced brushless shop, they basically told me that the NIMH was going to be VERY heavy and possibly thermal the speed control (which is rated at 99 amps continuous) and recommended running TWO 11.1v 3 cell lipo's in series for a total of 22.2 volts, or a 3 cell and a 2 cell for a total of 18.5 volts. I believe he mentioned that they were 3 cell 3000 mAh lipo's, and could handle a 99 amp burst? does this sound correct?
My question is this- When I am looking for Li-pos that can handle that kind of amp draw, what am I looking for? I am trying to figure out the formula that will give me a particular batteries max amp draw. I know it has something to do with the batteries mAh rating, voltage, and 20C or 30C rating, but cant figure out the formula. Any help would be appreciated!
Thanks!
I am building a Associated 1/10th scale RC10L pan car as a project. The goal is the 90 mph range. The original plan was 16-18 "C" NIMH cells for a total of 20ish volts, a Lehner 2800XL or 3100XL brushless motor, anda BK WARRIOR 9920 speed control.
After talking to a experienced brushless shop, they basically told me that the NIMH was going to be VERY heavy and possibly thermal the speed control (which is rated at 99 amps continuous) and recommended running TWO 11.1v 3 cell lipo's in series for a total of 22.2 volts, or a 3 cell and a 2 cell for a total of 18.5 volts. I believe he mentioned that they were 3 cell 3000 mAh lipo's, and could handle a 99 amp burst? does this sound correct?
My question is this- When I am looking for Li-pos that can handle that kind of amp draw, what am I looking for? I am trying to figure out the formula that will give me a particular batteries max amp draw. I know it has something to do with the batteries mAh rating, voltage, and 20C or 30C rating, but cant figure out the formula. Any help would be appreciated!
Thanks!
02-23-2006, 08:54 AM
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RE: Li-Po amps question for a Top speed car
Oh, and I honestly don't know what kind of Amps my motor will draw under load with the tall gearing. I just was told 99 amps would be a safe number-
02-23-2006, 10:51 PM
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RE: Li-Po amps question for a Top speed car
Dear Thickstack
You can play with the figures yourself and it will be more fun. Open LIPO Expo/LIPOCALC II at
http://www.fmadirect.com/tech_data/lipoCalc/index.htm and plug in 22.1V as the voltage (That is a 6S pack) and 99 amps. I should assume the 99 amps is the peak the speed control can handle. The KOK 3200 in a 6S2P pack will run the car for about 3.5 minutes at 99 amps. probably by that time, the ESC would be history. So assume that the continuous is about 70% or 70 amps by reducing throttle to 70 %. the run time is now 5.5 minutes and that is probably very realistic and doable.
In the event that you want longer run time, we have coming into stock a 4.8 AH pack that could be done in a 6S2P for 9.6AH. if you want to play with that, use the custom lie at the bottom of LIPOCALC II.
Please stay in touch. call us and talk to Eric at X12 when he gets back from the WRAMs show in NY next Tues. if you are from teh NY area, fell free to hit the show and talk to our crew there.
[email protected]
You can play with the figures yourself and it will be more fun. Open LIPO Expo/LIPOCALC II at
http://www.fmadirect.com/tech_data/lipoCalc/index.htm and plug in 22.1V as the voltage (That is a 6S pack) and 99 amps. I should assume the 99 amps is the peak the speed control can handle. The KOK 3200 in a 6S2P pack will run the car for about 3.5 minutes at 99 amps. probably by that time, the ESC would be history. So assume that the continuous is about 70% or 70 amps by reducing throttle to 70 %. the run time is now 5.5 minutes and that is probably very realistic and doable.
In the event that you want longer run time, we have coming into stock a 4.8 AH pack that could be done in a 6S2P for 9.6AH. if you want to play with that, use the custom lie at the bottom of LIPOCALC II.
Please stay in touch. call us and talk to Eric at X12 when he gets back from the WRAMs show in NY next Tues. if you are from teh NY area, fell free to hit the show and talk to our crew there.
[email protected]
