Help! Problem with Assist

[Caramoz]

Hi! I just bought a used Fischer Proline 1401. However there seems to be a problem with the assist. While riding it even though I can hear the motor the assist doesn’t kick in at all. However when the bike is upside down for examination the assist does kick in in that the wheel is going round but most of the time not at the level set but at a lower level. Sometimes it kicks in at the correct level though ( but never kicks in while riding)
I don’t have a manual. Trying to get one but don’t hold out much hope. Fischer just seem to have generic manuals online and not one specific to that model ( even if it says it is the display and controls etc are different.
I’m a total novice with these bikes so it may be something I’m doing wrong. Would greatly appreciate some help!!! The battery is fully charged by the way
Thank you

 

[sjpt]

Could be connections. Make sure all the connections are fully tight and the battery is properly seated, and the battery connections clean.

Could be a dying battery. Even a very tired battery will take full charge, but will just fall off immediately there is any attempt to take significant power from it.

 

[vfr400]

If you can hear the motor turning, but it's not driving the bike, either the clutch is faulty or you've stripped the internal gears. If you tell us the circumstances when the problem started, we should be able to say which of the two it is. In either case, you have to open the motor to see what's wrong. You have a Shengyi motor that has dogs to unscrew the side-plate, which means you have to make or buy a tool to open it.

All such motors work the same, so if you can't open it, you can replace it with any motor wheel you want.

 

[Caramoz]

Could be connections. Make sure all the connections are fully tight and the battery is properly seated, and the battery connections clean.

Could be a dying battery. Even a very tired battery will take full charge, but will just fall off immediately there is any attempt to take significant power from it.

Thank you!! But this doesn’t explain why it works when it’s not being ridden?? Or does it?? Is there any way to test the battery ?? Anyway it shows full charge and doesn’t deplete at all ...would this be the case if it was dying??

 

[Caramoz]

If you can hear the motor turning, but it's not driving the bike, either the clutch is faulty or you've stripped the internal gears. If you tell us the circumstances when the problem started, we should be able to say which of the two it is. In either case, you have to open the motor to see what's wrong. You have a Shengyi motor that has dogs to unscrew the side-plate, which means you have to make or buy a tool to open it.

All such motors work the same, so if you can't open it, you can replace it with any motor wheel you want.

Thank you!! Ok I couldn’t actually ride the bike when I bought it as it had a flat tyre. But we tested it by lifting it up to check that the wheel was turning and it was. So changed the tyre etc but now it doesn’t kick in while riding it but does if it’s upside down and we’re turning the pedals ( albeit not at the level that it’s supposed to be ...but sometimes it does) Hope that makes sense??

 

[Gliggsy]

Have you tried to offer resistance to the drive wheel whilst it's upside down other than applying brakes?

 

[sjpt]

Thank you!! But this doesn’t explain why it works when it’s not being ridden?? Or does it?? Is there any way to test the battery ?? Anyway it shows full charge and doesn’t deplete at all ...would this be the case if it was dying??

Yes, when you are riding the battery is having to give significant current to drive you along; when just running with the wheel off the ground there is almost no resistance so almost no current is needed to turn the wheel. The depletion will still be fairly slow even on a dying battery when the battery isn't actually generating much current. The only way to test is if you can measure the voltage at the battery while riding. Some meters show that; even on a new battery the meters instantly show voltage sag when you drive hard uphill.

Much of the same argument applies to any clutch; enough friction to turn the wheel but not enough to drive you along. vfr400 has much more experience than I do; so it's more likely his theory is correct. If it is the clutch the motor will turn quite fast on a good battery as it is only driving itself.

 

[vfr400]

It's simple. If the motor stops when the wheel stops, it's an electrical problem, and if the motor turns while the wheel is stopped, it's the internal gears or clutch. In rare circumstances, it can be the woodruff key between the clutch and motor shaft that snaps.

If the seller genuinely didn't know about the problem, I would guess that the bike had been left for a long time and the clutch has gone rusty. They must have rdden it to get the puncture and the puncture wasn't fixed, so the bike hasn't been ridden since.