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Old 09-15-2008, 12:42 AM   #1
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Default 4 and 5 cell gearing ???

How would you gear a brushless motor running 4 cells and running 5 cells as opposed to the regular 6?

Would you gear up or down??

I would use a Novak 5.5L or 8.5SS in my T4, B4, or BJ4.


Thanks for any replies.
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Old 09-15-2008, 12:52 AM   #2
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How would you gear a brushless motor running 4 cells and running 5 cells as opposed to the regular 6?

Would you gear up or down??
You have to gear up (lower FDR). Not just a little bit, at least a few pinion teeth.
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Old 09-15-2008, 01:05 AM   #3
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Back when I was trying 5 cell I believe I went up about 3 teeth.
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Old 09-15-2008, 01:44 AM   #4
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Thanks for the info.

I have also heard that the motor uses more of the battery capacity with less cells, is that true?

Is it just because you gear up or do less cells get taxed more by the motor somehow?
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Old 09-15-2008, 02:28 AM   #5
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Thanks for the info.

I have also heard that the motor uses more of the battery capacity with less cells, is that true?

Is it just because you gear up or do less cells get taxed more by the motor somehow?
There is a larger current draw to compensate for the "missing" voltage. If we were to say that 5.5t/4 cells = 8.5t/6 cells, hen your setup might roughly comsume a third more current than the later.
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Old 09-15-2008, 02:45 AM   #6
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There is a larger current draw to compensate for the "missing" voltage. If we were to say that 5.5t/4 cells = 8.5t/6 cells, hen your setup might roughly comsume a third more current than the later.
No...if the resistance of the motor and speed control remain the same and the voltage drops, the current would then drop.

You'd have less IR in the battery pack because you have one less cell...but you're mostly going to use more battery because you're going to be on the gas more and you're running a taller gear...or a lower-resistance motor.
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Old 09-15-2008, 07:35 AM   #7
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Thats right - the 7.2v motors are less efficient at lower voltage.
So what gearing / Motor / ESC Combos are you guys using for 4cell 2WD Mod.?
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Old 09-15-2008, 02:00 PM   #8
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A lower weight car will accelerate faster than a higher weight car.

Because it is lighter, your 4 cell setup can be designed to accelerate faster than your previous 6 cell setup IF you chose the right gearing and motor.

As far as your gear question goes, I would say try lower AND higher...you never know!

Last edited by haulin79; 09-15-2008 at 10:27 PM.
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Old 09-15-2008, 11:53 PM   #9
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My idea is to try a Novak 5.5 Lite with GTB in my BJ4 with 4 x 4200 cells.
I will try a FDR of around 9.75, 78 spur with 20 pinion.

I will temp gauge it after 5 minutes and maybe decide to gear up more.

If i ran my B4 i would probably use the same gear and ratios.

How does this sound?
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Old 09-16-2008, 12:01 AM   #10
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5 cell didnt really work out in 4wd because you need to torque provided by that 6th cell. In 2wd it really smoothed out the power band and made it much easier to drive on loose/low traction tracks. Thats just what a teammate and I found in testing.
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