Unwanted regenerative braking while pedaling.

[GordonT]

Hello all. I'm a new member. Just joined for this issue. I searched this thread (service and repair), but couldn't find anything similar. Maybe because I am mis-diagnosing the problem?

I have a Rad City 3 (2019). Great bike (heavy beast ). 1800 km. Lately, I've been having what I think are electrical problems. I've contacted Rad with the issue, but only bots have answered so far.

When I'm trying to bike  in  the power assist mode, I think the bike is trying to regenerate power into the battery. This leads to the pedals being intermittently slowed down, and then allowed to operate normally. which makes a very difficult ride. Sometimes the charging is seconds, other times dozens of seconds or even minutes. Good thing is the battery stays charged 

The regeneration is stopped if I turn the throttle. So now, whenever I want to bike, I have to keep the throttle engaged. it doesn't have to be much, but since it is on the same handlebar as the gear shifter it is annoying.

I don't know if this is a cable problem, or a controller problem, or perhaps a problem with the brake calipers themselves. I think the problem first occurred during a ride, right after braking. I was wondering if this was a known problem for any of you.

Thanks!

Gordon

[handlebar]

I don't know from personal experience, but I think all Radpower motors have freewheel, so they can't slow  you down.

My Radmission is somewhat like a Radcity. The PAS sensor, which tells when I'm pedaling, is between the left pedal arm and the bottom bracket. It's a black ring with a wire coming from the bottom. I think yours is intermittently failing to send pulses to tell the controller you're pedaling, so the motor stops helping you.

I have no first-hand knowledge of sensor problems. Maybe there's a bad connection, or the sensor is out of place, or the magnet it senses is out of place, or you need a new sensor. Someone here has complained that the sensor ring broke in half.

There's bound to be someone here who knows more about it than i. They might know how to pull the crank arm off and if a generic sensor would be a good replacement. On Amazon I've seen a replacement that can be installed without removing the crank arm, and I think a reviewer said it worked on a Rad bike.

[GordonT]

I don't know from personal experience, but I think all Radpower motors have freewheel, so they can't slow  you down.

My Radmission is somewhat like a Radcity. The PAS sensor, which tells when I'm pedaling, is between the left pedal arm and the bottom bracket. It's a black ring with a wire coming from the bottom. I think yours is intermittently failing to send pulses to tell the controller you're pedaling, so the motor stops helping you.

I have no first-hand knowledge of sensor problems. Maybe there's a bad connection, or the sensor is out of place, or the magnet it senses is out of place, or you need a new sensor. Someone here has complained that the sensor ring broke in half.

There's bound to be someone here who knows more about it than i. They might know how to pull the crank arm off and if a generic sensor would be a good replacement. On Amazon I've seen a replacement that can be installed without removing the crank arm, and I think a reviewer said it worked on a Rad bike.

Thanks for this. I will check the wiring down there, at least rule out a loose connection.

[handlebar]

Another possibility occurred to me. Last year I bought a Radmission. I got in the habit of holding a button a couple of seconds to shift because sometimes it was slow to recognize the signal. Even then, it could miss shifts. It could also double shift if I hit bumps while holding the button.

The controller had a rubber plug on one side. To see if the problem was moisture, I found a length of vinyl tubing small enough to insert. I have a 6-gallon compressor with a 25-foot hose and an attachment with a trigger valve. I screwed a tapered brass end into the attachment and pushed it into one end of the tube. I put the other end of the tube into the controller box. I set the regulator as low as it would go, about 8 psi. I tied the trigger down with a clove hitch and turned on the compressor. The tube was now bringing a stream of very dry air into the controller. The regulator kept the flow slow so that the compressor was off most of the time.

I let it work about 15 minutes, and for some weeks the shifting worked fine. When the problem recurred, venting with dry air would fix it. The controller seemed well sealed, and I didn't ride it in the rain. Apparently the humidity in the air could make it act up. Eventually I got an aftermarket controller.

If humidity could cause my controller to miss shift signals, maybe it could cause yours to miss PAS pulses.

[GordonT]

OK. I've figured the issue out, with some very helpful direction from Rad City service support (Cassandra).

As handlebar intuited, it had to do with the PAS. The sensor was fine, but the magnetic ring that goes around with the crank spindle had cracked, and was not tripping the sensor while I pedaled.

RAD is sending (free) a one time replacement of the ring, which I guess has failed often enough to be an issue. School has started, so today I repaired the broken ring (epoxy, nylon and electrical tape). It works for now, I'm not sure how many violent bumps it will withstand. Of course, the next few days will most likely be too hot to get much cycling in, but I got to practice taking the crank off, so putting the new ring on should be a charm. It is supposed to arrive next weekend or early the next week.

Thank you handlebar, for your insight. If I had known more at the time, your hint would likely have lead me to the solution. I know much more about the bike than I did 40 odd days ago, and that can only be a good thing. I've also got tools that I didn't know about previously, so there is that.

Keep on cycling, and thanks for the help.