Absolute Maximum Current Discussion - Set to 150% Max Current or to Controller's Current Rating?

Help Desk
1

Curious what the General Consensus is on what to set Absolute Maximum Current to: 150% of Motor Current Max, or the Max Current rating of your controller? Assuming that 150% of Motor Current Max is within your controller’s rating of course.

Have seen both said and done, so curious what the general consensus is, especially from those who might know better haha. Of course there’s other factors, such as how conservative manufacturers are in stating controller specs, as well as how likely they might be to overshoot beyond Max Current.

In general, a lower Absolute Current Maximum (150% Motor Current Max) prioritizes protecting the controller and assumes your motor control loop won’t overshoot beyond 150% of your set max. While a higher Absolute Current Maximum (setting to controller’s spec’d maximum current) prioritizes protecting the rider against potential cutouts from motor current overshoot for any reason. Thoughts?

2

I’d say it depends on the context. If it is for a race, I’d always prioritize the rider’s safety, same logic as choosing a charge only BMS for instance.

Manufacturers always use a safety factor; that being said, from my experience electronics are far more sensitive to overload/surges than motors. You might just fry the controller while the motor would still run, though that doesn’t mean it’s not damaging it overtime.

3

Main difference here compared to the charge-only BMS or low vs high voltage cutoff comparison, is if you prioritize “rider safety” too much and blow your controller from excessive peak current somehow, that’s obviously still gonna drop the rider haha, rather than just something like running too low voltage degrading/damaging the battery. So there’s a balance there for sure.