Motor Cutting out intermittently

joceton

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12
Hey folks, just upgraded to ONYX 4000kv Motor and 70 amp ESC combo (ONXS0501) with a Spektrum STX 3 radio (SPMTX300) and receiver. I'm running a 7.4V NIMH battery, at 3300 mah. my first run with it this morning, the motor would cut out intermittently, but would return when I turned off the ESC and turned it back on. During this time, I did not lose steering. The instructions stated that the receiver requires 3.5V and if the receiver falls below 3.5 it could cut out. The other piece is the ESC states that the default low cut off voltage is 3.0 V per cell. I can adjust the low voltage cutoff, but is the simple solution here that my NIHM at 7.4 V is just not powerful enough, and I need a Lipo battery? Its a pretty big powerplant, so maybe the NIMH just isn't enough?
 
You can run the NiMH battery if you set the LVC to 0. The low voltage cutoff is designed for LiPo not NiMH chemistry. NiMH does not need and can’t run long with a cutoff enabled.

That said - run a LiPo. I moved to a 2S LiPo on the stock brushed truck and electronics and it worked great. I now have a brushless system in it and it rips.
 
I have the same Onyx combo on my AMP and indeed, you MUST turn off the voltage cutoff if you re using NIMH. I know the Onyx manual seems to imply that there is a voltage conversion for NIMH and it should work, but my experience is that it doesn't! Just turn off the low voltage cutoff (LVC) on the ESC.

Also the esc does have an issue: You cant accelerate and immediately reverse. It has a huge delay basically: Accelerate, stop (1-2 secs) then reverses.

This is a problem if you are wanting to reverse mid air on jumps to control your vehicle in the air.

By the way I switched to Lipo (turning LVC on, obviously) and the punch is MUCH greater and fun. And also faster.
 
That run mode is standard on all ESCs. That is what you want, forward and when you reverse it is proportional braking. Reverse only engages after you stop and then push the throttle title to reverse. To go from fwd to reverse would be extremely hard on the motor and drivetrain. The good news is you don’t need to, hitting a jump and hitting the brakes will rotate nose down. Not as much as a 4wd of course but it still works well enough to make your landings flat.
 

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