Ok to Ride Ebike Without Battery?

[geeeyejo1]

Ok maybe a stupid question - but I have assembled and connected my Yescom Rear Hub kit as per previous build thread. I want to road test the bike to ensure gears and brakes are set properly. I do not have my battery yet. Can riding the bike without the battery generate any current that could damage the controller? I understand phase connectors could short against each other but if connected to controller will all be ok?

 

[SamTexas]

Yes it's ok. That's one of the idea behind an electric bicycle, you can still use it without the battery.

 

[Icewrench]

Foggy recall but maybe with a direct drive motor some folks have had problems going downhill fast without a battery???
If you need to test ride it stay slow or disconnect the phase wires from the controller.

 

[amberwolf]

I don't see any problem with it; as SamTexas says, it's kind of the point of htese things--the bike is still a bike, too.


It is possible that on a steep downhill with a non-freewheeling motor, you could coast to a speed that would generate a voltage higher than the controller could handle, but that isn't somethign that would be different with or without a battery. The voltages would still be on the phases themselves, even if the controller was powered off, and if the voltage across two phases grew beyond what the FETs between them could handle, they could fail. If they failed shorted, you could experience a nastily quick end to the ride as it could add so much sudden drag to the wheel that you could lose control (and on a front wheel if you're fast enough and in a forward tuck, down a steep hill, you could even flip over the bars). But these are not very likely things to have happen in most cases just riding around, with or without power. You'd ahve to be going very fast, probably much faster than most poeple feel safe going downhlll on any bike--certainly faster than teh bike could go on the flats by motor power alone.

 

[itchynackers]

FWIW, I rode down Pikes Peak with regen the whole route, and nothing bad happened.

 

[amberwolf]

I think you would be more likely to damage somethng by *not* using regen or other braking, because the voltage across the phases could be high enough for damage if you are going fast enough--but as I said above, it'd have to be at minimum faster than you can go with the motor on the flats at WOT, as that is essentially the same voltage out of the motor as put into it, so the FETs have to be safe with that voltage already.

It';s just when you go higher in phase voltages than the FETs can take, that you need worry. Probably not going to happen for most people.

(although myself I always worry about Johnson and Murphy)

 

[dogman dan]

Shouldn't be a problem. Won't damage a controller unless it's defective anyway. You will experience some resistance, and the faster you pedal the more the resistance will seem to incerase. You won't be going fast enough for what AW was talking about. I've coasted down some big mountain passes without damaging controllers.

Also, you could just unplug the controller from the motor. Nothing bad could happen then except for the motor wheel coming loose from the bike if the nuts aren't installed correct.

If you have a short in the phase wires, you'd have a LOT more resistance. So that's one way to check for a shorted controller. Plug it into the motor and if it's resisting more than before, the controller has shorted a fet.

You can "lock" an ebike, by unplugging the controller and plugging in a wire that deliberately shorts the motor phase wires. With the plug in place, it will be incredibly hard to ride it away.

 

[geeeyejo1]

Thanks guys - I ended up " bench testing" her today - I have a pully system that raises the bike off the floor for minor repairs and allows to manually rotate the pedals and shift gears. The 6 speed twist index shifter I installed works perfectly with the freewheel that came with the kit! The rear rim is so much wider that the original I had to open the Vbrakes to prevent rubbing. The wheel spins free but you can definitely feel the resistance of the magnets in the hub. Quick question- how many times should the rear wheel spin free before the magnets stop it?
I also wrapped and secured the rear wheel wiring routing it up the leg of the rack to the battery bag - nice and neat now!
Been raining all weekend but will definitely take her for a small road test to see the efficacy of the brake adjustments before I go under power.