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Old 02-28-2007, 07:40 AM   #1
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Default Mamba 7700 and 3s Lipos

Hi guys, Ive been reading into this alot lately and was looking for some advice.

Basically what i have read

The Rotors are limted to 65000rpm hence why the motor is limited to a 2s lipo pack, however to me it doesnt make sense.

heres why

a 2s lipo is 7,4v x 7700kv = 56980rpm

however when charged, a lipo reads 8.4v

so 8.4 v x 7700 = 64680rpm which is the supposed limit of the rotor.

However CC say the 5700 is the quickest as it can actually run 3s

so 11.1v x 5700 = 63270rpm

And when full charged, is around 12.2v

12 x 5700 = 68400rpm which is over the safety threshold.

So my point is this. What is the real LOADED KV of the mamba motors, namely 7700. If this can be worked out then I can run a 7700 with a 3s lipo and run some resistors from the battery so that I can limit the voltage so that it maxes out at 65000rpm. This way I wouldnt have to buy another motor. Otherwise I could just use the software to peak the throttle curve at around 85%.

If this is not possible, then i guess I wil have to buy the 5700, but im pretty sure this would work fine.

So please let me know what u think.
Thanks
Dean
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Old 02-28-2007, 08:43 AM   #2
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Default

A lipo at the load expected at full speed cruising will be around 3.9V/cell, and that's probably a high (safe) estimate.

Don't use resistors. Limiting the throttle throw after calibration is much better.

The interesting part is that Castle could fairly easily program in a rev limiter that is adjustable through the Castle Link. But, they haven't.

They also haven't got the ESC to work with other brushless motors.
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