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Old 08-04-2008, 03:16 PM   #1
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Default Brushless Motor with 2S2P or 4S1P? Small or Large Pinion?

What are your thoughts on the following in selecting a battery/motor/pinion combination?

A. Battery/Motor Selection:
(With A123 cells)
1. 2S2P (with a high kv motor) or
2. 4S1P (with a low kv motor)

B. Pinion Selection
(assuming equal power output and equal top speed)
1. "low-rpm/high-torque battery-motor combination" with a larger pinion or
2. "high-rpm/low-torque battery-motor combination" with a smaller pinion

If brushless motor manufacturers published dyno/efficiency plots I would be able to see each motor's rpm and voltage sweetspot and make sure that I am operating in that regime with my pinion selection and battery configuration.

Last edited by haulin79; 08-05-2008 at 12:14 PM.
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Old 08-05-2008, 11:44 AM   #2
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Do you plan to race? What is this going in? These are needed to help you in your quest. The easy answer is that high v/low kv will be more efficient, Lower load on the batteries and longer runtimes. The lowv/High kv tends to pull more current and have lower runtimes. I have both setups right now, A rc10GT conversion with 5s lipo and a T4 with 2s lipo, both are strong and fun, but the 5s setup will run nearly a 50 minutes on a 2500 lipo where the 2s will get close, but with a 8000 mah lipo. To answer your question properly, you need to answer the two question above first
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Old 08-05-2008, 12:17 PM   #3
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I think you answered the battery part of my question. What you said is that high-voltage low-current is more efficient than the high-current low-voltage.
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Old 08-05-2008, 12:50 PM   #4
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The thing is, if you race, you will have to follow rules. If they have a 2s limit, you got to go with it.

One thing i forgot on the High V vs low V, thats geared for the same speed, not the same gearing. You get higher draw with higher V and same gearing, than low V. sorry if its a bit confusing
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Old 08-05-2008, 02:38 PM   #5
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I will be getting a B44 or a Caster Racing EX1 only $375


I don't race...but I do practice on the race track. I'm into RC for the product development side.
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