MP5 max speed dropped from 42 to 32kmh

[Dainis]

Hi! Any clue why after a wheek of riding my MP5 with fully charged 48V battery can reach only 32 kmh instead of 42kmh? What may happened?

[Bikemad]

Hi Dainis andto the forum.

It sounds like the Maximum RPM setting may have changed.
Using the USB programming cable or Bluetooth dongle you will need to check if Maximum RPM setting is still set to 360/380 rpm.

Alan
 

[Dainis]

Hi!
I checked with USB. It is set to 380 rpm but bike do not go over 273. 

[Dainis]

I connected throttle wires directly and MP worked just fine. Verdict the throttle needs a repair or a change. Any suggestions?

[Bikemad]

I connected throttle wires directly and MP worked just fine. Verdict the throttle needs a repair or a change. Any suggestions?

The throttle signal output should be above 3.25V at full throttle for the motor to run at maximum rpm.

If it is not reaching this voltage at full throttle, it may be a problem with the throttle Hall sensor itself (Honeywell SS49E Hall sensor can be used as a replacement), or it could just be a poor connection on the throttle signal wire between the Hall sensor and the cable connector, or it could even be due to a weak (or dislodged) magnetic strip inside the throttle unit.

As you have only been riding for a week, I presume that the throttle will still be covered by the warranty, so I suggest that you contact the seller and explain the fault and ask if they can send you a replacement throttle unit under the warranty.

Alan
 

[Dainis]

  Just received replacement throttle. It has the same problem as previous. Does it have too big resistance? I noticed also that without connected bluetooth MP spins faster.

[Bikemad]

It sounds like the +5V supply coming from the controller is a bit on the weak side and the voltage is dropping with the additional load of the Bluetooth dongle.
If plugging in the dongle reduces the +5V supplying the throttle Hall sensor, then the maximum throttle output signal voltage could also be reduced.

If you can measure the +5V supply on the Pedelec connector (measure between the Red and Black wires) you should be able to see if it is noticeably dropping.

I suspect it may be a poor +5V voltage regulator in the motor controller, but it might also be worth temporarily unplugging the brake switches to see if it makes a difference, as a partial short circuit within the brake switch wiring could also cause a similar fault.

Alan