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Old 08-17-2011, 04:04 AM
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Foxy
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Default RE: RC18T or T2 for a high speed car?

The T2s are not ideal for speed runs. While the people saying go shaft 'for the durability' are mistaken (belts can take twice as much power as shafts, and transfer that power more efficiently as well), it is actually due to poor design of the T2's specific belt system that it doesn't make a good choice. For racing it is a great car once you've worked out the kinks, and that's simply because in racing people use lower Kv motors for shorter periods of time with lower voltages, negating the heat and runtime issues that plague the T2. I couldn't get more than 5-10 minutes at a time out of a 3S 7500kv setup on that car, and I have now given up on it and will be selling it. Since then I bought a little Xray (my second one of these, but first brushless, previous was years ago) and I'm thrilled with it, it goes like stink and will finish a battery (20mins+) without getting anywhere near dangerous temperatures (using the exact same motor and ESC and very similar gearing that I had in the T2).

Get an Xray M18T pro if your budget will stretch. It's so much better than everything else out there, it puts the rest to shame (but you will have to pay for it ), see pic below.

Yakfish, the main advantage of increasing voltage is less amp draw. More cells is more efficient, as less strain is put on each cell. The power the motor uses is an expression of Watts. So lets say a 5000kv motor uses 400W at 37,000rpm max throttle with 2S. Since we know that watts=amps*volts, if you use a 2s battery (7.4v) that means 400W divided by 7.4v=54A. Now take the same situation and use 3 cells (11.1v) and the SAME RPM (in other words at 2/3rds throttle), it's using the same watts but more volts, your calculation becomes 400W divided by 11.1volts=36A. HOWEVER, now that you have added voltage, your motor will rev higher, using more watts, and therefore more amps, generating more heat. Bottom line though, more volts means less current for the same power.
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