36v20 CS suitable for 500W 36v scooter motor?

Hi

  1. Would the 36v20 CS be suitable for driving the 500W 36V 17A rated motors commonly found in electric scooters, assuming active monitoring is done on the current sense pin for stalling?
  2. Are these controllers regenerative in any of the driving modes e.g. will they feed power back to the batteries if current is removed from the motor?

Much obliged … :slight_smile:

Hello.

The motor driver is probably insufficient for your motor. Stall is probably going to be past 100A, and you will likely be exceeding 17A all the time in normal use. However, if you happen to have a use that keeps the motor under the load it is meant to handle, you might be able to get away with this driver. You should probably use a fuse in addition to the current sense monitoring.

Like all H-bridges (I think), some operating conditions will lead to power getting sent back to the batteries.

- Jan

I am confused with the answer posted here based on the 2nd Paragraph in the “Real-World Power Dissipation Considerations”. pololu.com/catalog/product/1457 - It states:

Because there is no internal temperature limiting on the motor driver, the entire system should be designed to keep the load current below the 20 A limit. An easy way to achieve this is to select a motor with a stall current below that limit. However, because a good motor can have stall currents dozens of times higher than the typical operating current, motors with stall currents that are hundreds of amps can be used with this driver as long as the running current is kept low. For example, a motor with a 100 A stall current might run well at 10 A, leaving a safe margin for the current to double for several minutes at a time or to triple for several seconds. If the motor does stall completely for a prolonged period, however, the motor or driver are likely to burn out.

The Scooter Motor in Question: “500W 36V 17A”, You stated “The motor driver is probably insufficient for your motor. Stall is probably going to be past 100A, and you will likely be exceeding 17A all the time in normal use.”

These two statements are confusing me.

I have a “500W 36V 17A” ebike hub motor with a Stall Current of around 120A. If I use the “36v20 CS” and the current monitoring controlling it to say 17A, will this driver be ok to use? I will likely add a heatsink to allow for more current margin.

I think the advice is that, yes, if you can keep the current below 20A, this will be safe, and if that gives the performance you want out of the motor, then that’s great!
However, during acceleration, it’s likely the motor will want to draw a lot more current, and thus the necessary current regulation may prevent you from getting great performance out of the motor.
It’s impossible to tell exactly which shade of grey this will fall out as without actually testing the specific case, though.

Hi.

What it comes down to is that 17A is a lot more than 10A, especially when the 10A is already presented as a borderline case. The closer you operate to the limit, and with a motor that is likely to draw well past the limit, the more vigilant you have to be about currents and temperatures; that in turn means it will be more of a pain in the neck and more likely that a mistake will lead to destruction of the driver. Plus, you might end up with a lot less power out of the motor than you need.

So, I still advise against it.

- Jan