Bafang Ultra Fatbike build

[Daxxie]

amazing build. is installing the phaserunner something a newb could do?

what are your speeds and battery life with this setup?

thanks

It wasn't so hard to install. But you have to be comfortable with cutting wires and soldering on new connectors.
I modified the Cycle analyst from JST to Higo connectors.

Mounting the Phaserunner inside the Ultra is not for the faint harted. (There is a hacksaw involved!)
Making the Ultra's torque sensor work was the hardest part.

I will put some instructions for people who would like to do the same.


About speed and battery life. I still have to build the battery for it.
I ordered 120X 30Q's to make a 72V 20S6P battery.

With the "old" battery of my other fatbike (52V 14S5P 40A max)
it reaches a top speed of 59km/h. @2200W

[Daxxie]

The reason for installing a Phaserunner was:

- I had another Ultra drive at home with a broken controller. And spare parts are impossible to find.
- I wanted more power.

The plan was to remove the Controller and replace it with the Phaserunner.
But would a phaserunner fit inside an Ultra drive?

Only one way to find out.
I ordered a CA3 and a Phaserunner and took some measurements.

First I hooked it all up and did some tests.



The Ultra runs quite well with the PR.

The Phaserunner is about 1cm to big to fit inside the Bafang drive.
With a little modification (hacksaw!) it might fit.

The PR can be shortened a bit.



And the motorcasing needed some milling.

[Daxxie]

How I wired it:


Phase
Phase wires go to Phase wires on Phaserunner


Hall
Hall Connector has 6 wires.
5V and Ground + 3 Hall sensors and a white cable that is a NTC thermistor that I connected to the CA to monitor the temperature.


PAS
It took some time before I figured this one out.

The Ultra's PAS needs 5V, you can steal 5V and ground from the CA or from the Phaserunner. (There is 5V and ground at the PR throttle connector.)
The CA didn't pick up the PAS signal from my Ultra. I had to add a 20K pull-down resistor between Pas signal and ground to make this work.
The Green Dir cable is not used
The Purple Pas Phaseshift is connected to the dir tab on the CA
Brown Torque goes to the Trq on the CA.

My Ultra had a Higo6 connector for the PAS with the right colours, which made it a bit easier.




This is a diagram I made:



I used the standard Bafang Speed sensor.
Gearsensor and 1X Magura MT5e rear brake.

[Daxxie]

Some Ultra motors have the white connectors for PAS/Torque.
How to determine which wire is which?




+5V and GND is easy.
You can see it on the backside of the controller board.



I still have a picture of my plug that will make it easier.


orange | purple | white
black | brown | green

These colors correspond with :

+5V | Pasphase | PAS
Gnd | Torque | Speed/Dir



You can check with a multimeter

Between Gnd and PAS : gives you a pulse signal when rotating the crank FWD and REV 0V | 5V | 0V | 5V etc...

Between Gnd and PASphase : gives you a pulse signal when rotating the crank FWD and REV 0V | 5V | 0V | 5V etc...

Between Gnd and Speed/Dir : gives you a pulse signal (0V or 5V) when rotating the crank FWD and 5V constant when pedaling backwards

Between Gnd and Torque : gives around 1V and a bit more when you put torque on the pedals.

[weetard]

Some Ultra motors have the white connectors for PAS/Torque.
How to determine which wire is which?




+5V and GND is easy.
You can see it on the backside of the controller board.



I still have a picture of my plug that will make it easier.


orange | purple | white
black | brown | green

These colors correspond with :

+5V | Pasphase | PAS
Gnd | Torque | Speed/Dir



You can check with a multimeter

Between Gnd and PAS : gives you a pulse signal when rotating the crank FWD and REV 0V | 5V | 0V | 5V etc...

Between Gnd and PASphase : gives you a pulse signal when rotating the crank FWD and REV 0V | 5V | 0V | 5V etc...

Between Gnd and Speed/Dir : gives you a pulse signal (0V or 5V) when rotating the crank FWD and 5V constant when pedaling backwards

Between Gnd and Torque : gives around 1V and a bit more when you put torque on the pedals.

yup, too much for me! thanks for posting tho!


i got the bbshd coming this week...ill just run it with the stock settings!

[JPLabs]

Awesome info in this thread!! Thanks.

[AZguy]

+1

Very awesome. That is very mechanically different than the BBSHD and from the photos looks well-engineered and manufactured particularly given it's chinese.

Three sets of reduction gears vs. two in the BBS. Do you know the reduction ratio(s)?

[ncmired]

Do you know the reduction ratio(s)?

Eric (with Josh) said 25:1 during the Luna Ultra teardown video (2:38 point): https://www.youtube.com/watch?v=1lki_sGQfJ0

This motor, along with the Max and some other Bafang "integrated" motors, might have more chainline correction possibilities via the splined chain ring spider. I would like to see wider market acceptance for this motor series.

[Daxxie]

+1

Do you know the reduction ratio(s)?

The Bafang Ultra has a Reduction ratio of 1:18.26

9t Motor shaft > 23t
25t > 66t
17t > 46t

9/23 * 25/66 * 17/46 = ~ 18,25569 : 1

[AZguy]

That's *less* than the BBS - I'd have thought they'd gone with a higher reduction (higher motor speeds)... It's believable - it appears from the photos each reduction is not very great. Perhaps same motor core with same KV and lower reduction will give a higher top speed for a given battery if same KV motor.... dunno...

[AZguy]

I was thinking the same.... Just off the top it should be easy to confirm same poles and coils but who knows about the windings....

Enquiring minds want to know =]

[JPLabs]

I guess coil resistance and inductance (capacitance, help me here....) might be a good indicator? If either are significantly different, then motor winding design must have changed? Resistance actually might match, if thicker but fewer windings were used, so we need more than that, right?

[AZguy]

Wouldn't worry about C but L and R would be very telling...

[ncmired]

Apologies for my bad reference info - what's the BBS02/BBSHD reduction ratio(s)?

[AZguy]

Very close to 22:1

When I took mine apart I made notes:

8 poles
12 coils
9t (motor shaft)
32t - 11t (nylon gear and shaft)
68t (secondary reduction final)

9:32 * 11:68 = ~21:97979...:1

[xcnick]

How does the Ultra do bottom bracket size?. I realize no bottom bracket per se, but I want the big Q factor to go around a fat bike tire. Really just the chainring from center as far as possible.

[ncmired]

Really just the chain ring from center as far as possible.

I thought that maybe they could accommodate a pretty wide range of chain lines using different depth spline chain ring carriers, out to a hard limit set by the drive side crank spindle distance. But I've not seen other chain ring carriers available, or even if the Max chain ring carriers would fit on the Ultra.

[TOLM]

Amazing build. So clean. As good as a fat e bike can be