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VintageMA · 11.27.2006, 05:58 PM

Be careful with the calculations on power density. If you drop from a 4Ah cell to a 2Ah cell (regardless of the # of S) you still lose the amount of current you can push out. Even if the cell was fully capable of pushing out 20C you are dropping from being able to safely push out 4Ah x 20 = 80 Amps to 2Ah x 20 - 40Amps. With twice the voltage across the ESC and motor, the current draw will go up and it is likely that you will ruin the cells.

As a side note - I am (was) running a 9920 in a 1/8 buggy conversion with a 7XL motor and 4S @ 9000 mAh - close to 30 minute runtime with WOT geared 14/46 with MOD1 gears. The buggy weighs close to 9lbs with the batteries but I easily get over 40MPH, not sure exactly how much over, but I run in a park along side a road with a 40MPH speed limit where people tend to drive faster and I can easily keep up and pass. The motor gets warm (never over 130-140) and the 9920 stays just barely warm to the touch.

I was in the same pradicament as yours when I accidentaly drove through a very deep puddle this past weekend and my ESC went up in a huge cloud of silicone smoke 5 minutes later. After reading the articles of people having all these heat problem with the Quark, and never having a single problem with my 9920 on 4S I decided to go ahead and order another 9920.

My question now is would the 9920 handle 6S? I have two 3S @ 8000 mAh packs I am going to run in series with a a MGM 16024 and LMT 1950/7 motor on a LST2, but would like to try the 6S on the buggy while I wait for the motor to come from BK.

	(#4)
VintageMA RC-Monster Aluminum Offline Posts: 660 Join Date: Sep 2006 Location: CT	11.27.2006, 05:58 PM Be careful with the calculations on power density. If you drop from a 4Ah cell to a 2Ah cell (regardless of the # of S) you still lose the amount of current you can push out. Even if the cell was fully capable of pushing out 20C you are dropping from being able to safely push out 4Ah x 20 = 80 Amps to 2Ah x 20 - 40Amps. With twice the voltage across the ESC and motor, the current draw will go up and it is likely that you will ruin the cells. As a side note - I am (was) running a 9920 in a 1/8 buggy conversion with a 7XL motor and 4S @ 9000 mAh - close to 30 minute runtime with WOT geared 14/46 with MOD1 gears. The buggy weighs close to 9lbs with the batteries but I easily get over 40MPH, not sure exactly how much over, but I run in a park along side a road with a 40MPH speed limit where people tend to drive faster and I can easily keep up and pass. The motor gets warm (never over 130-140) and the 9920 stays just barely warm to the touch. I was in the same pradicament as yours when I accidentaly drove through a very deep puddle this past weekend and my ESC went up in a huge cloud of silicone smoke 5 minutes later. After reading the articles of people having all these heat problem with the Quark, and never having a single problem with my 9920 on 4S I decided to go ahead and order another 9920. My question now is would the 9920 handle 6S? I have two 3S @ 8000 mAh packs I am going to run in series with a a MGM 16024 and LMT 1950/7 motor on a LST2, but would like to try the 6S on the buggy while I wait for the motor to come from BK. “Everyone has a right to be stupid; some people just abuse the privilege.”