MPIII on 24 volts: power surges

[Vnomad]

Greetings. New here. Magic Pie 3 in Norway 

My MP3 has been running like a champ for about 3 years now. It has been USB programmed for 36 volts, running on a 36v battery.

Recently I "inherited" a nice 24 volt battery, and reprogrammed the unit for 24 volts. It runs, but not steadily. Instead I get intermittent surges followed by depowering with approximately 1 or 2 second intervals as I try to accelerate. I have verified that the battery stays steadily above 24 volts while riding.

Is this a known issue? Is there a  recommended solution?

TIA!

[Bikemad]

Hi andto the forum.

Does this happen when using the throttle, or only when using the pedelec sensor?

This pulsing effect has been observed by some members, but I think it is only when using the pedelec sensor.

If you are using standard GM pedelec sensor, you might be able to improve the surging by adjusting the PAS and/or Acceleration settings.

If that doesn't help, using a "Voltage mode" pedelec sensor connected to the throttle signal wire should cure it.

Alan
 

[Vnomad]

Thanks for the Welcome, and helpful reply
It happens as I turn the throttle only.
The pedelec wires are not connected at all. In the Personalized Setttings Uint1.1 PAS is left on "high", Acceleration on 100%.
I have noticed a similar, but much weaker pulsing tendency, when I connect a 36v battery while the controller is still programmed for 24v. This occurs as the battery voltage drops slightly under nominal.
I looked through the "Voltage mode pedelec sensor" thread referenced, but does not that option also require installation of an accessory Cycle Analyst?

[Bikemad]

I have noticed a similar, but much weaker pulsing tendency, when I connect a 36v battery while the controller is still programmed for 24v.

Have you tried setting the controller to 36V and using the 24V battery?
This won't work with later MP4 or MP5 controllers because the 36V low voltage setting will be too high for a 24V pack but it may work with your MPIII controller.

I looked through the "Voltage mode pedelec sensor" thread referenced, but does not that option also require installation of an accessory Cycle Analyst?

The Cycle Analyst allows greater control over the Pedelec sensor signal output, which means it can be fine tuned to suit the rider, but The Voltage Mode pedelec sensor should still work OK without a Cycle Analyst if wired directly to the throttle signal wire.

If the output signal from the Voltage Mode sensor was passed through a suitable variable resistor (probably 3-5KOhm) it should be possible to adjust (reduce only) the assistance relative to the pedal rpm.
More magnets could be added to the magnet ring to increase the assistance relative to the pedal rpm.

Alan