BAFANG motor issue

[Robequain]

Hi,

I am cyclist (able for maintenance on any bike) but new e-bike enthusiast using a BAFANG motor with C963 display.
I have a cargo-bike (Yuba) which is secondhand bike used daily for school drop and pick-up (2 kids).

The joy ended end of December. It is not working anymore. Motor stopped when riding back from school…

As it was secondhand bike, I didn’t know how old the battery was (and what was previous owner usage), so it was for me the obvious root cause. A new battery arrived yesterday, and it did not fix the issue. During the battery installation, by random, I was able to see that the walking assistance is working fine (pedals are spinning with by using the “ – " button).
The old battery did power the C963 diplay and I was still able to see that the speed sensor is working fine, but I thought that the battery delivered enough power for the display, but not for the motor.

It means that the battery is OK and that the motor is not totally out of order.

Thanks to the walking assist mode, I was able to test the brakes sensors, and both are working fine: it is properly stopping the engine when I use the breaks but let the motor go if no break…

I checked all the electrical connections inside the motor (and just to make sure, I unplugged and plugged back all of them). At the end, I have the same (bad) result: walking assistance working fine, but no motor when spinning the pedals.

Do you have any idea? Thank you very much in advance for your time and help.

 

[tomjasz]

Which Bafang motor?

I kindly suggest you own a multimeter. It's a primary tool and important if you want help and to learn to troubleshoot.

I'm guessing that since it's a C963 display the motor could be 3-5 years old. It could well be a problem display. I haven't seen a C963 available in several years.

If it's a Bafang mid-drive there will be markings under the motor. A picture would be helpful. That was I can see the build date and the model version.

After re reading I'm leaning towards the display. You say the speed sensor is flashing when the magnet passes and the brake sensors are functioning and you have power. It would be interesting to know the state of charge. Both batteries fully charged?

 

[Robequain]

I will buy a multimeter and learn how to use it. Never used one.

Bafang motor is (as indicated under the motor): BBS02B 48W 750W 16050778688
I think the first 4 digits = DATE = May 2016 ?

The display seems to be OK.
A long time ago, after rear wheel problem issue (ball bearing replacement), I had the error message 021 (speed sensor issue) and it was making sense. I fixed the issue, the sensor was not in the right position...
Today, I can read the speed when the rear wheel is in move.
When the wheel is moving, I can see also a red light shining near the speed detector. Everything seems to be OK.

The 2 batteries are fully charged.

Sorry for the quality of the pictures, I did too quick. The water on the Serial Number picture is just water used to do the cleaning under the motor. The motor is in good shape, no infiltration.

Thanks.

 

[tomjasz]

Well if batteries check out at 54v, you’ve checked speed sensor, brake cutouts function, throttle is functional, you’ve checked wiring harness for continuity on all pins, there are no error codes displayed...

It sure does sound like a display problem. C963 were in little use in May of 2016. I grabbed a few of the last available because I like simple. But they did fail and we’re more 2014 tech.

Bottom line, display, throttle, or wiring harness.

 

[Robequain]

Thank you for you help. Today, I will stop by a e-bike shop that was recommanded to me.
I will sure update this discussion when I will get the "pedal assist" feature back.

 

[harryS]

Does this bafang have a throttle, and does it work? I didn't see that written up. I know Walk mode was described as working.

If throttle works, and pedal assist does not, it could still be a bad pedal sensor in the motor. If neither work, it could still be electronics in motor.

Unless your ebike shop does Bafang conversions, you'll be paying for them to learn how to buy and swap components.

 

[tomjasz]

I guess I missed the mark here. It's only pedal assist that doesn't work?

We have had motors come in with loss of PAS due to a controller failure. Sometimes troubleshooting means checking every possibility. A BBS02B pulling a cargo bike and kids is under a heavy load. The controller do overheat and do fail. Individual controller components can fail, making troubleshooting a real pain.

Using high levels of PAS and being in a road gear when taking off can definitely create issues too.

 

[Robequain]

Hi,

Answer to Harrys: I am not sure about the "throttle" ; I think I don't have any on this bike. I choose a level between 1 to 9 on the device, then I use my legs to pedal when I want to start, and then the motor is helping (a lot). In order to keep moving forward, I always use my leg, very ligthly and the motor runs... Very enjoyable. But no throttle I think.

Answer to Thomas: yes, absolutely, only pedal assist is out of order. It might be a "loss of PAS due a a controller failure".
But how to make sure? What do you call the controller? Is it the C963 display? Is it a piece which is inside the motor?

I understand that a cargo bike might be heavy (total charge with kids and bags might be 330 pounds + bike itself) but it did so well for 6 months that I think this is not the root cause. Our usage is limited to quite flat paths, and short ones, around 6 miles per travel twice a day. I don't think this is controller overheat. The issue happened in December, was quite cold. And the bike was fine in June when it was hot.

"Using high levels of PAS and being in a road gear when taking off can definitely create issues too" => I do a lot of road cycling without motor, so I am used to always have the right gear, easy one to start, then switching to a bigger development when I go fast. I am helping a lot the bike when it starts. The motor had this issue as we were riding quite fast. It was not just after "taking off".

Anyway : how can I make sure what piece is out of order ? Display, internal piece within the motor ?
How can I find a Bafang specialist in New York (Manhattan would be a dream for me)?
Or should I buy now a new motor? If so, what is the best model for a cargo bike?

Thank you very much.

 

[harryS]

Your prior owner may not have installed the throttle, if this was a DIY kit. If there is a dangling cable coming out of your motor, that would be a throttle connector, and I believe you could just have a shop try installing one and seeing if the motor works. If it does, it could be ridden by feathering the throttle as a work around.

Check that a brake lever cables are in tension with the levers closed. Sometimes a cable gets loose, the brake lever droops open, and the brake switch embedded in the lever will disable the motor.

Your bike may have a gear sensor too, so make sure the shift cable is taut. I have never seen a gear sensor though, so this may not be be how it's checked.

On the BBS02, The PAS sensor is inside the motor. It's the 4 harness in this (awful) video at 1:09. The sensor itself is about 25 dollars.

 

[tomjasz]

The throttle connection is out of the harness with the brakes and display, not a wire dangling from the motor. Usually motors this old won’t have a gearsensor connection direct to the motor.

 

[Robequain]

Hi,

Thank you for the 2 last comments. It helps me a lot.

I do have a wire free out of the harness with the brakes and display. It is protected with tape, and, following your advice, I will try to connect what you call a throttle connection.

But I do have also a wire dangling from the motor (see picture Motor2.jpg). This wire is not protected by tape... might be dirty or salty... Could it be the issue ? The fact is that is was not connected to anything, so it is not clear what is the purpose of it.

Should I buy this product

Bafang Brake/Throttle/Gear Sensor Extension Cable (12")– Ebike Essentials

This is a 12" Bafang Brake and Throttle Extension cable for Bafang ebike conversion motor kit ebrakes, ebrake sensors, throttle and gear sensor. The cable has 3 pin yellow higo connection plugs to connect to Bafang ebrakes, throttle, and gear sensor.

www.bafangusadirect.com

and make the connection between the free wire out of the harness with the brake and the one available dangling from the motor ?
If yes, I will buy 2 or 3 of them to have the sufficient lenght.

If it doesn't work, then I will buy a new motor unit (arount $500) and feel free to play with this one by opening it and learn more how they are built.

 

[harryS]

Here's the BBSHD wiring diagram, which is the same as the BBS02.

Bafang BBSHD Wiring Diagram - Mid-Drive eBikes

Bafang BBSHD Wiring Diagram courtesy of LunaCycle.com

rpev.org

I'll have to look at my throttle connector. Maybe we can suggest some ways to test it w/o having to buy a throttle.

.

 

[tomjasz]

The taped over connector will be the throttle on the harness. Out of the motor with two wires and a flat plastic connector will be a 5v lead for a light. If the wire out of the controller is a round Higo connector, just like the connectors for the brakes it is a Gearsensor connector. And yes shorted wires anywhere can create gremlins.

 

[tomjasz]

Sorry I missed the motor2 picture. that is a Gearsensor connection. No you don’t need to do anything with the Gearsensor cable. Do not connect it to anything except a Gearsensor. You could safely attach a throttle to the throttle lead from the harness. But only a Higo connector throttle from a BBSxx seller.

 

[harryS]

Your dangling harness connector should look like this. Unfortunately, these are male pins and are just too small for me to suggest testing them.

 

[tomjasz]

Call me tomorrow at California eBike tech support. I’ll help sort it with you. For the cost of flat rate shipping I can send a display and correct throttle to test. Including a harness to eliminate that possibility. OR you can send the motor to our shop for testing and repair. Changing a controller is easy but expensive if not the problem. Ideally there would be some one close to help. Repairing often means going through multiple possibilities. Not always straightforward as one would think. 5 years of supporting and building with BBSxx motors and I discover new twists frequently.

 

[Robequain]

Hi Thomas, sorry for my late reply. I will call you this afternoon.
Yes, display + correct throttle and new harness is interesting for testing.
After the test, I could ship the motor to your shop, but I am wondering about the total cost back and forth shipment and if it worth it?
What will be the cost, according to you ? The other solution is to buy a new motor if the issue is not fixed with the throttle.

Is it legal to ride a bike with a throttle? I am not so sure in NYC, so it is good for the testing but I will have to benefit from the Pedal assist sensor on a long terme perspective... I like it better than using the throttle I think.

I will call you in order to pay and share my mail address.

 

[tomjasz]

Hi Thomas, sorry for my late reply. I will call you this afternoon.
Yes, display + correct throttle and new harness is interesting for testing.
After the test, I could ship the motor to your shop, but I am wondering about the total cost back and forth shipment and if it worth it?
What will be the cost, according to you ? The other solution is to buy a new motor if the issue is not fixed with the throttle.

Is it legal to ride a bike with a throttle? I am not so sure in NYC, so it is good for the testing but I will have to benefit from the Pedal assist sensor on a long terme perspective... I like it better than using the throttle I think.

I will call you in order to pay and share my mail address.

I'm down with the flu today, but will return any call I miss.

Others will have to answer whether a throttle is OK in NY.

Looking back I missed whether you had any error code on the display? I'm thinking the C963 is limited in code compared to other newer displays.

A new bare motor with a warranty is $400. FEDEX shipping is around $40 one way. Making a repair at least $200. Finding a local shop would likely be a better solution financially. These motors have has small and incremental improvements since 2016.

 

[tomjasz]

Which electric bike motor is best??

Which eBike motor is best?

www.sleekrides.com

Tarryton NY about 25 miles away looks a good prospect.

 

[Robequain]

Sorry for the flu!
Today I have no error code on the display, but I had once the 21 for speed sensor issue. Was easy to fix.
I will be in touch with Sleekrides and will let you know.