Bafang Ultrawithout hall sensors

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garyal1   10 W

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Bafang Ultrawithout hall sensors

Post by garyal1 » Jul 11 2019 7:55pm

I was in the process of converting a second Bafang Ultra bike from 48 volts to 72 volts with the Grin PR and CA3. I did one already at 60 volts and liked it so much, I bought all the items from Grin and a large capacity triangle battery.

When I went to remove all of the internal Bafang controller and such, I found this unit is different from my 1st one. It does not have hall sensor wiring! It has a little magnet on the end of the motor shaft and that spinning gives some signal to a board and that somehow simulates the 3 hall sensors. This cannot be used with the PR and CA 3.

So I tried doing the sensor-less auto tune and it does run the motor. It does so after some bang and pops. Not a smooth start up like my other unit with hall probes.

Can anyone tell me if this will give me a lot of problems? Should I just abandon this project and leave it at 48 volts with Bafang controller and 30 amps? Should I go ahead and install it in sensor-less mode without hall sensors? It seems like it would not be good unless I only had the motor start after pedaling.

Can I buy some hall effect sensors and install them into the windings?

Looking for advice......

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amberwolf   100 GW

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Re: Bafang Ultrawithout hall sensors

Post by amberwolf » Jul 11 2019 10:33pm

garyal1 wrote:
Jul 11 2019 7:55pm
It has a little magnet on the end of the motor shaft and that spinning gives some signal to a board and that somehow simulates the 3 hall sensors. This cannot be used with the PR and CA 3.
Why not?

If it gives 3 outputs that match the phase positions, then it doesnt' matter if it's actually hall sensors or not, as long as the signals are the same and the same timing.

garyal1   10 W

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Re: Bafang Ultrawithout hall sensors

Post by garyal1 » Jul 11 2019 11:10pm

The reason it cannot be used is because it is all internal in the control board for the stock Bafang controller which I was going to replace with the PR and CA3:

1) The control board will be removed.
2) The circuits are internal to this board so even if I could leave the boards in the system I could not get the singals out to the Grin unit.

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