Front hub works in walk mode, not with PAS.

[rich_r]

I've just fitted a Panda 250W 36V Pro front hub kit to my wife's bike - all went pretty smoothly apart from the front wheel going in the wrong direction with the wire coming up the left fork. Luckily I tested it in walk mode as it said in the manual to discover that issue...

So now with the wheel the other way round, it pulls forward in walk mode at 5kmh, which I take to be a good thing. However when I ride the bike and pedal there's no sign of the motor doing anything despite the red LED on the PAS sensor flashing every time a magnet on the disc passes it. I've checked that P3 is set to 1 in the KT LCD (though not changed any parameters since supplied)

The only thing I'm wondering about at the moment is maybe my battery setup. As I couldn't afford to buy the kit and a lithium battery in the same month, I decided to use some 5Ah sealed lead acid batteries that I have many of temporarily to test things. I have three in series giving me a terminal voltage of around 38V unloaded, but only 5Ah obviously. That seems enough for walk mode, and the battery gauge is showing full initially..

I'm going to try six batteries (3S2P) tomorrow when they've charged to give me 10Ah at 36V - although I am very aware that SLA discharge characteristics are very different to lithium battery ones.

Could this be the cause of the lack of power to the hub motor when pedalling?
Or is it worth me speaking to Panda just in case there's something wrong with the controller?

 

[Deleted member 4366]

The battery will make no difference. Are you testing on level 0, in which case the PAS is disabled?

 

[rich_r]

I've started off by cycling slowly with the assist on 0, then increased it to 5 but there was no sound from the motor or change in the relationship between the bike's speed and the amount of effort I was turning the pedals.

 

[Deleted member 4366]

Just to eliminate the obvious: the red light flashes when you turn the pedals forward?

 

[rich_r]

Heh, yes - it flashes when I pedal forward (ie I can see it flashing when I'm cycling along normally).

 

[Deleted member 4366]

Have you got brake switches? If so disconnect them.

 

[rich_r]

Disconnected brake switches - no change.

I tried putting all six batteries on so there's 10Ah at 38V) anyway as I had them ready - no change (not that we expected there to be any though).

Checked the pins in all the connectors (they're the waterproof round black type) - though I guess it's possible there's a break in the signal wire from the PAS sensor to the controller or between the connector and the controller.

The LCD seems to show speed and distance correctly so I guess that means the sensor in the hub are working and in all probability the LCD unit is fine too.

 

[Deleted member 4366]

How many pins in the connector - 3 or 4?

 

[rich_r]

Three pins in the PAS sensor plug. It's got a yellow plastic interior.

 

[Deleted member 4366]

Have you got a throttle you can try?

Right, the only logical conclusion is that you have it plugged into the wrong connector. Are there two connectors the same?

No, cancel that. You have the harness with the Julet connectors.

 

[rich_r]

Sadly not. I could probably rig something up if it's a simple potentiometer though. 5k Ohms seems a common value quoted.

Tomorrow if I get chance I'll see if I can work out what each pin is on the PAS sensor. I see from previous posts on here it most likely would be +5V, 0V and a pulse output. I'll see if my oscilloscope shows anything happening on that output pin when a magnet is moved near.

 

[Deleted member 4366]

5k or 10k pot would work, but you need to figure out which pins are which. You can use a meter to test which is 5v and which is ground. Connect those 2 to the outer pins on the pot and the remaining one to the wiper. The controller needs to see a zero throttle signal before it'll respond to anything else, so you need to turn the pot right down first.

 

[rich_r]

Oliver is sending me a KT-LCD3 display so I can take a look at the C parameters. My existing KT-LCD1 can only get at the P ones. Hopefully it just needs the setting for the PAS type and sensitivity altering.

I didn't get chance to drag the oscilloscope out to the garage (or cut all the cable ties to take the sensor into the house), so I'll work with Panda to find what the problem is.

And if my car passes its MOT without too much expense next month, I'll buy a lithium battery (and possibly a throttle).

 

[rich_r]

All sorted

With the KT-LCD3 display I can adjust the C settings on my Kunteng controller. C1 was set to 7, which according to the manual seems to be correct for a 12 magnet PAS sensor. I set it to 8 and it now responds to the pedal rotation.

Oddly though, 8 isn't listed as a valid value in the LCD3 manual. So I might try it on 5 or 6 which are (5=most sensitive, 6=sensitive, 7=standard).

But tonight I got my first taste of what a 250W front hub pedelec is like, even with the 5kg weight of SLA batteries on the back. Tomorrow I hope to go for a longer ride to see how long my batteries last and enjoy the feeling of assisted cycling. Or actually what'll happen is that my wife will enjoy it (it's her bike), whilst I try to keep up on my unassisted bike...