Speed control mobility scooter.

[CJay]

I did give the solder side of the pcb a good look under a large light magnifier. I couldn't see any bad joints, or dry one's, it's a single sided PCB through hole circuit.

I dunno which board that is but it's not the one in the first post.

[davelectronic]

Yes it's the same board, not a very good image as taken in poor light and flash not working. I have two of some components (pcb's) I'm sure I've got the right one photographed. I will double check. I've acquired a few spare parts from a friend that has scrapped a bit of electrical stuff, I asked him if he comes across control units and any tiller circuit boards if he'd keep them for me. Probably never need them, but they don't take up much space. All I know is the solder side of the tiller circuit board looks fine. I think the software parameters need looking at first. Then if there ok, then there is a fault somewhere.

[aqibi2000]

What do you understand from circuit boards?

There are basically no high power semiconductors shown anywhere on your pcb and ONLY relays.

Only 1 high wattage ceramic resistor at the bottom which I believe would be the soft start… check this and it’s subordinates

Therefore it’s not variable speed it’s all relay driven, as simple as can be!

[davelectronic]

The control unit is responsible for the pwm to the motor. That's rated at 24 Volts 70 Amps, I understand the tiller PCB circuit is mostly low power relays, one or two would be responsible for switching a larger contactor in the motor controller. My knowledge is that of a hobbyist that is interested in analogue electronics. I can get the scooter to crawl along slowly, but for slowly to full speed is to sudden, with not much variable control Inbetween very slow to full speed. So it doesn't behave very linear across the electrical travel of the throttle potentiometer. I'm going to have a look at the software parameters first I think, as if I change any components, it could inevitably affect these parameters where it's not intended. If that doesn't fix this, I might replace the motor controller and electrical brake. It can not be direct relay start at full power, just relay on or off. Have you ever applied full voltage to a brushed DC motor and noted the sudden huge torque that creates. If it where like that, it would very quickly destroy the motors armeture and commutator, and probably the start relay. It has to be low voltage controlling the motor controller, implicating pwm as the control mode.

[aqibi2000]

Replace it with your own BTS7960 43a brushed controller.

Easy to control, use and interface to. And only £7

[CJay]

Replace it with your own BTS7960 43a brushed controller.

Easy to control, use and interface to. And only £7

Which will fry in seconds if you try and use it for the motor in that scooter.

[DavidAlfa]

Check the blue module, that's what makes the power regulation.
Also, it could be a mechanical problem, like backlash in the gears.