Powabyke repair.

[birdtrek]

Trying to repair a dead Powabyke. 36V front wheel motor with SLA batteries. Replaced the batteries. Fitted pack and all the lights show up. It doesn't power the motor. I've disconnected the joint between the motor and controller and my voltmeter shows 38v which doesn't change whether you pedal or throttle.
Any way of determining if the fault is the motor or controller?
Any help much appreciated. Thanks. Chris

 

[Alan Quay]

IIRC those are 36v brushed DC motors. If you are supplying it with 38v and it does not turn, it's the motor (or wiring to it).

Does it have two wires going in?

 

[birdtrek]

Hi Alan,
Yes, has block connector with two wires going to motor.
As the voltage is 38v even without throttle or peddle power, am I correct in assuming that the controller sends the voltage at a very low amps and increases with throttle twist?
If I put 36v direct to these two wires going to motor would that be a way of fault finding?
Thanks.
Chris

 

[Deleted member 4366]

If you put the battety voltage directly to the motor, it should spin. Be careful, it might spark a bit where you join the wires, and don't forget that it ill go at full speed.

For anybody else, you can't do that with your motor unless it's a brushed one.

 

[birdtrek]

Update.
Made up two cables to connect to block connector and offer to battery off bike. The motor came to life immediately and yes at full speed.
For anybody else trying this, I put the bike stand on blocks and weighted the rear end so the motorised front wheel could spin. I then used bungees attached to handlebars to keep the front wheel straight.
I presume the next best thing would be to check every wire the controller uses?

 

[Deleted member 4366]

Controllers don't cost much, but ones for brushed motors with a connector for a pedal sensor are very difficult to find.

When brushed controllers fail on their own, it's normally the output fets that go, which causes full speed as soon as you switch on. Others are wiped out when ham-fisted owners connect battery voltage to any of the sensor wires, like when they connect the wire for the throttle LEDs to the throttle itself. That's a very easy mistake when people don't know what they're doing.

 

[birdtrek]

Could not find any bad connections. It would be disappointing if the controller was faulty. I bought the bike as 'dead' and the charger had developed a fault and the batteries had just been left too long.
Is there anyway I can check the controller and throttle sensor independently? Would it make sense to buy a controller with throttle?

 

[Deleted member 4366]

The throttle has three significant wires, which are normally red for 5v, black for 0v and another colour for the signal wire. If you can find any way to connect a 5v supply to the red and black, you can measure the voltage between the signal wire and the black, which should change from 1v to 4v when you open the throttle.

A healthy controller will have 5v between the red and black throttle wires when connected to a battery and switched on.

 

[birdtrek]

Update.
This controller has two inputs, throttle and pedal sensor. I have 5v between red and black on both feeds.
Measuring at the joint feeding the throttle I seem to have about 4v when throttle not used dropping to 1v when twisted.
I did try using the pedal assist joint with the throttle but that made no difference.
If I connected the red 5v to the signal wire would that mimic 'full throttle' and if the motor kicked in would that prove that it was the throttle faulty or would I just damage the controller?
Many thanks
Chris

 

[Alan Quay]

Most controllers are clever enough to spot 5v and 0v as throttle fault/not present. That's why the signal is 1-4v.

 

[Deleted member 4366]

It looks like your throttle is working backwards for whatever reason. Normally, the controller won't give power until it sees zero throttle. You can try switching everything on with the throttle disconnected. Hold the throttle fully open and connect it, then let it down a bit to see if it works. Make sure that the motor wheel is off the ground.

 

[birdtrek]

Update:
Measuring the voltage more carefully this time at the back of the throttle connector ...... it seems to be minus 4v at off and minus (-) 1v when twisted.
I missed the - sign last time, sorry.
At the back of the pedal assist connector, this is 5v whatever.
So can I presume that both the pedal assist and throttle are faulty?
Thanks ..... Chris

 

[Deleted member 4366]

That's OK. I see to remember from another thread that Powabyke throttles work backwards. So, throttle is working, battery is working and motor is working. I've never ridden a Powabyke, but someone said that there's some strange logic in how it works. IIRC, you have to pedal first before the throttle is allowed, but after that, it works normally. There's two switch positions that changes something somehow. Have you read the manual?

 

[birdtrek]

No I hadn't read the manual - but I have now.

'quote'
The ignition has two settings.
The first ‘click’ gives Pure Power when pedalling to start it then you can stop pedalling. This is be controlled by the throttle. If you stop and do not pedal for 5 seconds the motor will cut out.
The second ‘click’ gives power when pedalling is constant. Again this is be controlled by the throttle. As soon as pedalling ceases the motor will cut out. It is possible to switch between ‘modes’ whilst the bike is moving.
'unquote'
So my constant 5v at the pedal sensor joint means that it is faulty and so the throttle won't kick in to get the motor going. If there was some way I could fool the controller to think the pedals are turning, I could prove the rest was working.
Thanks .... Chris

 

[Deleted member 4366]

Not correct. 5v is the power to the throttle and pedal sensor to make it work. When your controller is switched on, the 5v is activated. There's a CPU in the controller that reads the pedal sensor and throttle signal wires, which it then processes to decide how much power to give. Everything seems to be working. Did ou try pedalling to activate the throttle?

 

[birdtrek]

d8veh you are a genius. It powers up
Working out how to get two wheels off the floor and turn the pedal and throttle the same time proved the most challenging.
If I had road tested first after fitting new batteries .......
...... but at least now I understand how the electrics work on this model.
Many thanks for your help.
Will take it to local country park tomorrow to see how it performs.