MX25V2 current limited

[Leonsmits]

Dear Sir,

I have Fido 500W geared wheel conected to GM MX25V2 controller. Battery is 35 AH 48v with JK ballancer.

Motor is driving max speed about 50 km/h, so I limited to 55% in software (about 28 km/h now). Acceleration is set to 100% in software, but still have little torque. When speeding up scooter I can read in JK ballancer app motor is consuming 15Amps. When motor has reached max speed (28Km/h) motor is consuming about 7 amps.

It looks if controller current is limited to 15 amps, but in the software I set voltage to 48v and max current to 40 amps. Because my scooter has no peddels and I don't have PAS sensor, I left PAS in the software in the "high" mode.

Please advice to get more power.

Kind Regards Leon

[Bikemad]

Hi Leon andto the forum.

Most BLDC motors will draw their maximum current at very low speed, and the current being drawn from the battery will automatically decrease as the motor rpm increases (and when the motor reaches its maximum governed rpm) which is why the current draw is so low at 28km/h.
However, if you were doing a constant 28km/h whilst going up an incline, I would expect the current draw to be higher than 7A.

Please note that a battery current draw of just 15A @ 48V = 720W, which is still 44% higher than the motor's 500W rating.

The Max Current settings available in the miroMAX version of the programming software is 30A Continuous and 70A Peak:



Unfortunately, I think this value is for "Phase Amps", which are typically much higher than "Battery Amps".

You could try setting the controller's "Motor Voltage" parameter to 24V instead of 48V to see if the torque increases.

Alan
 

[Leonsmits]

Hi Alan,

Thank you for reply. I will try 24v setting.

But it seems that the acceleration curve is so defined that from standing still and accelerating it takes a while before 15Amps is consumed by motor ( the current is slowly building up). I would expect when starting with full trottle moter would consume 15 amps immediate and taking down the current when reaching max speed.

Kind regards leon

[Leonsmits]

Hi Alan,

I tried and it worked, it makes a big difference in accelerating. Thank you for your advice, problem solved!!

Kind Regards leon

[Bikemad]

Hi Leon,

Thanks for the update, it's good to know that the 24V setting has cured the problem.

Alan
 

[Leonsmits]

Hi All,

In the software for setting " Max Current" you have continuous Amps and peak amps. I was wondering if the controller will shut off when reaching these settings or does the controller limit the current to these settings.

Kind regards Leon

[Bikemad]

Hi Leon,

The controller simply limits the Phase current output to ensure that it doesn't exceed the programmed settings.

However, if the controller becomes too hot under sustained high current output (and high current regen with a non geared motor), it may shut down completely to prevent internal damage until it cools down enough to allow normal operation to be resumed.

Alan
 

[Leonsmits]

Hi Allan,
I use high torque geared motor ( 48v /100n/m) 500W What would be the setting of peak current in the software? I want to limit at 800W power, but must I devide current by 3?

Leon

[Bikemad]

Hi Leon,

The Magic Pie Edge is also a high torque 500W motor (although it's direct drive instead of geared) and the default rated phase current is 56A with a default battery drawn current of 21A.

For a motor running at 80% efficiency, an output of 800 Watts @ 48V would require a battery current of 20.84 Amps, so the above mentioned Magic Pie Edge settings will hopefully be suitable for your motor too.

Default Phase Amps/Battery Amps ratios used on GM hubmotors:
Smart Pie: 50A/18A = 2.78:1
Magic Pie Edge: 56A/21A = 2.67:1
Magic Pie: 80A/30A = 2.67:1

Alan