Choosing 24V or 48V ODrive for a 6S Lipo system


#1

I just stumbled across this ODrive community and am eager to get hold of an ODrive and start testing. :star_struck:

I’m a member of another group that’s currently building mobile robots using reworked e-bike motors (similar to these). The typical setup uses a pair of 24V/250W/328RPM motors, and a 6S lipo battery. The motor specs seem similar to the hoverboard motors that @madcowswe is using on Project HoverArm. The 6S lipo would be a little over 25V when fully charged.
My question is; would this push the project over the specs of the 24V ODrive (3.4) and require the 48V version? Or is a 6S battery within the 24V specs?


#2

Cool, I’m excited to see how it goes, make sure to keep us posted about any builds with these.

Hm it’s a tough call, the bus capacitors are rated to 25V, and I actually don’t know how much shorter their life span is if you go over slightly.


#3

Thanks! I’ll play it safe and go with the 48V version, and will definitely share my experience.

Another couple of quick questions;
These motors have hall sensors, which I see were once supported by ODrive in place of an external encoder. Eventually, is it planned to support hall sensors again?
Also, I see that during startup motors will move as a homing procedure. Do they typically do a full rotation, or is it just a small amount?


#4

Yes the plan is to support hall sensors again, can’t tell you how soon that will be though.
The encoder calibration procedure moves 2 electrical turns, so it depends on the motor. For example if your motor has 30 permanent magnets - > 15 pole pairs - > the motor will turn 2/15th of a turn.
If you have an encoder with index pulse you can set it up to only move to the index, which may be shorter if you set it up right.