Twisted gear sensor cable, now BBSHD won't respond

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
Post Reply
hbgb
10 µW
10 µW
Posts: 6
Joined: Sep 29, 2017 11:29 am

Twisted gear sensor cable, now BBSHD won't respond

Post by hbgb » Jan 13, 2018 2:53 pm

Hello, newbie here. The last few weeks I've been working on converting my first fat bike with a BBSHD. I installed the BBSHD and plugged in the battery for the first time a week or two ago and both the throttle and the PAS worked fine. I didn't have my brakes set up though, so I didn't take it out for a real ride.

In the meantime, I started waterproofing various components mostly following this guide. I applied silicon sealent to the BBSHD gasket and liquid tape to various parts of the display and throttle. While I was waiting for those to dry, my new tires arrived and being excited about them, I wanted to do a quick test ride on my driveway after installing them. Nothing on the BBSHD was plugged in, so I simply tucked the cables into my battery bag a rolled around a few feet. Being the idiot I am though, I must've missed the gear sensor cable and I realized that it had wrapped around the crank. Here's some pictures of the damage:

Image

It's hard to see, but there is a tiny cut on the casing, but not much in the way of exposed wires. The cable was twisted pretty good though.

Well, after things dried, I put everything back together and plugged in the battery. I'm not using a gear sensor or speedometer (yet), so I just ziptied those cables them out of the way. The display turns on and shows the battery is fully charged, but when I engage the throttle or turn the pedals to engage the PAS, nothing happens. I did the following to try and troubleshoot:

- Checked all the connections. I had applied dialectric grease, but nothing looks wrong.

- Unplugged my ebrake.

- Tried a spare throttle. I would expect the PAS to work even if the throttle was broken, but worth a shot.

- Plugged in an ebrake sensor to the gear sensor and held the magnet up against the ebrake sensor. Didn't expect this to work either, but again, worth a shot.

So, I don't know how the gear sensor cable works, but my thought is that when the gear sensor cable twisted/ripped, the internal wires connected and are telling the motor to shut off. To someone with more knowledge, does that make sense? I figure a fix could be for me to cut the gear sensor cable below the twisted and fix the internal wires with silicon sealent or epoxy or something to keep them separated. Before I do something like that though, I wanted to explain my situation here. Any thoughts?

Thanks in advance.

User avatar
Rassy
1 MW
1 MW
Posts: 1958
Joined: Apr 08, 2007 10:58 am
Location: Eugene, Oregon USA

Re: Twisted gear sensor cable, now BBSHD won't respond

Post by Rassy » Jan 13, 2018 3:23 pm

I would be inclined to try what you suggest, particularly if you have no plan to use the gear sensor. Before cutting any wires you could just try to remove the outer part and expose the small wires inside. Also, those same wires may have been damaged inside the controller housing if you can't find anything wrong with the external wires. Hopefully it didn't pull stuff out of the controller.
-Rassy-
One Tadpole Trike equipped with a Bafang BBS02
https://endless-sphere.com/forums/viewt ... 28&t=69419
One Delta Trike equipped with a Bafang BBS02
https://endless-sphere.com/forums/viewt ... 0#p1291260

hbgb
10 µW
10 µW
Posts: 6
Joined: Sep 29, 2017 11:29 am

Re: Twisted gear sensor cable, now BBSHD won't respond

Post by hbgb » Jan 14, 2018 9:32 am

Rassy wrote:
Jan 13, 2018 3:23 pm
I would be inclined to try what you suggest, particularly if you have no plan to use the gear sensor. Before cutting any wires you could just try to remove the outer part and expose the small wires inside. Also, those same wires may have been damaged inside the controller housing if you can't find anything wrong with the external wires. Hopefully it didn't pull stuff out of the controller.
By "remove the outer part", do you mean the wire casing? Would you recommend just using a utility knife or is there a better tool?

Thanks for your suggestion about the controller. I'll try taking that off next. I guess if the worst case scenario is that I'm replacing the controller, then I'll consider myself lucky.

User avatar
Rassy
1 MW
1 MW
Posts: 1958
Joined: Apr 08, 2007 10:58 am
Location: Eugene, Oregon USA

Re: Twisted gear sensor cable, now BBSHD won't respond

Post by Rassy » Jan 14, 2018 12:38 pm

Yes, the wire casing is what I meant by outer stuff, so you can actually see if the wires have been damaged. Probably fairly tough stuff so a razor knife of some sort would probably be required, you may be able to score the entire length and then just pull the wire casing apart by hand.

As far as I know and have read elsewhere the gear sensor works just the same or almost the same as the brake cut outs so that when the circuit is connected the motor shuts down.

I wouldn't bother removing the controller except as a last resort, but there is a tangle of wiring in there and an extreme pull on one wire may have dislodged a connection, etc. With the controller just hanging by the wires you can carefully test the system to make sure it is working before putting it all back together. This is where a spare controller comes in handy so you can verify that it is indeed the controller that needs to be replaced.

My experience is all with the BBS02 models, but I expect they are wired pretty much the same.

Good luck getting it figured out.
-Rassy-
One Tadpole Trike equipped with a Bafang BBS02
https://endless-sphere.com/forums/viewt ... 28&t=69419
One Delta Trike equipped with a Bafang BBS02
https://endless-sphere.com/forums/viewt ... 0#p1291260

hbgb
10 µW
10 µW
Posts: 6
Joined: Sep 29, 2017 11:29 am

Re: Twisted gear sensor cable, now BBSHD won't respond

Post by hbgb » Jan 14, 2018 6:24 pm

Aha, I simply cut the wire below the twist and sure enough- it worked! Perfect timing too as I was able to test it out my fat bike on the fresh 10" of powder we got this weekend. I'll simply epoxy the end to try and permanently prevent the wires from ever touching again. And I'll be sure to zip tie what's left of the cord! Thanks for your help Rassy!

Post Reply