Reversing the polarity

G'day,

I am interested in getting the Bafang 48 volt 25a mid drive motor because it is programmable to go the speed you want it to..
Two things though that I am unsure of is if you can actually fit a 48V 20A lifepo4 battery to it without it overheating or damaging it..
the second thing is if i reversed the polarity of the motor to make it go anti clockwise instead of the normal clockwise rotation, I was wondering how would that affect the controller and the lcd display/reading?

I have a yuba mundo which i believe will fit a bafang motor.. though i do not believe that i should have to pull apart any gears with a mid drive..
I do have other ideas on how i could set up a mid drive motor, though that might take an external bracket to fix to the frame and i dont have the tools/resources to make and get what i need.. Blah..

Anyway, I appreciate any feedback about it.. the basics was putting positive to negative and negative to positive to run the motor anti clockwise while seeing if i can keep the 3 gear chain ring on the right side of the bike

You can use any battery of the correct voltage that can give enough current. The one that you have should be OK. You can't have a battery that's too powerful because the controller in the motor takes only the power that it wants.

You can't make the motor go backwards because it's a three-phase AC motor even though it uses a DC battery. The controller in the motor converts it to AC.

Yep, not like a brushed motor that can reverse. Direct drive motors can reverse, but assuming your bafang is a geared motor, reversing it would just make the motor spin but not the wheel. Because of an internal clutch/freewheel.

It has a freewheel on the final drive so can only go in one direction.
I use 44volt of Lipo on mine and it runs just great.
I also had a 48 volt Headway pack on it and it runs just the same.

dogman said:

Yep, not like a brushed motor that can reverse. Direct drive motors can reverse, but assuming your bafang is a geared motor, reversing it would just make the motor spin but not the wheel. Because of an internal clutch/freewheel.

Click to expand...

Well the basic idea was to reverse a motor and get another chain ring on the left side of the bike with a free wheel cog either on the motor or on the chain ring and run the power through the crank.. might lose a bit of torque, though still get the same basic results....

Just thinking of different ways to make it compact, or being able to use a hub motor on the back middle section of the yuba mundo would be good. though i need to know the sizes of the back ect.. i know i can more than likely get brackets made as i have seen one for the yuba ..
https://www.youtube.com/watch?v=R5ZdbAGKJ90
This one though below is to expensive..
http://urbancommuterstore.com/M-Drive-Conversion-Kit-for-Yuba-Mundo-V33-V4-YM-MDRIVEKIT.htm
I have lots of ideas.. I am trying to pick one that's viable and cost friendly if you know what i mean..

If the motor you have has disc mounts, you could put a sprocket on there instead. That'd give you the left side drive you're after, without turning the motor around.

Then the freewheel would be just the regular clutch/freewheel inside the motor.

This thread should be linked with the KFC thread :lol:

Doc

Just get a direct drive motor of some kind. Then it can become a motor that runs in either direction.

The more I read that first post, the more confused I get what you want to do. A bafang bb drive would not need to be reversed. Or ARE you talking about making a mid drive with a bafang planetary gear motor running in reverse?

Between the first two posts by the OP, I think that he's wanting to do essentially what teh Stokemonkey did, and drive a *leftside* chainring on the cranks.

If he wanted to thread on a sprocket or southpaw freewheel (and secure it somehow so it didn't unscrew) to the normally-rightside of the motor, and hook it in like that on the leftside, then yeah, he'd need to reverse the motor, but that won't work for the typical geared motor because of the internal freewheel/clutch (unless you take the motor apart and reverse that, too).


However, if the motor has disc mount, on the left side, all he'd need to do is bolt a sprocket to that (no freewheel needed because of the internal one, AFAIK), to drive a leftside chainring, as the orignal SM did.

amberwolf said:

Between the first two posts by the OP, I think that he's wanting to do essentially what teh Stokemonkey did, and drive a *leftside* chainring on the cranks.

If he wanted to thread on a sprocket or southpaw freewheel (and secure it somehow so it didn't unscrew) to the normally-rightside of the motor, and hook it in like that on the leftside, then yeah, he'd need to reverse the motor, but that won't work for the typical geared motor because of the internal freewheel/clutch (unless you take the motor apart and reverse that, too).


However, if the motor has disc mount, on the left side, all he'd need to do is bolt a sprocket to that (no freewheel needed because of the internal one, AFAIK), to drive a leftside chainring, as the orignal SM did.

Click to expand...

Well since then i had been thinking.. I could still get a normal mid drive kit.. say a gng if i can get a 48v 650wat motor and keep it on the same side as the chain.. just run the chain under the cog and then add two more cogs, the last one at the front being a tension cog. Either way just need to extend the chain a bit more and then decide whether or not to put the motor at the top cog or the back cog position..

A kit like this maybe?
http://www.aliexpress.com/item/60V-650W-or-48V-450W-ELECTRIC-BRUSHLESS-MOTOR-MID-MOUNTED-ELECTRIC-BIKE-KIT-Electric-Bicycle-Conversion/1378268464.html