Radwagon 4 with an interesting malfunction

[HardWaterATX]

Bought this bike second hand to add to the e-bike lending library that we are building for charity work. I knew that it didn’t work but since it came with two batteries and all of the extras I took the chance for $650, the fella said that he thought it was an issue with the controller. Wouldn’t turn on so I replaced the display at which point it fired right up. But now with interesting malfunction, it will speed down the road just fine on either PAS or throttle but the moment you stop giving it juice it will motor brake and throw an error 21 and won’t let you throttle again until it has come to a complete stop.

Their website lists the error as electrical so I replaced the controller as I bought one with the display just in case. No dice, and it’s only now that I’m thinking what I should have thought from the get go with a geared motor that isn’t freewheeling and shouldn’t be capable of motor braking. Is it possible that the clutch has failed and now when it’s not under power it is essentially turning itself into a generator which then sends current to a controller that is definitely not expecting that and throws the error? And if so is there even a fix for this that doesn’t involve replacing the motor which you can’t even get from the partially defunct Radpower company?

I’m not against opening up the motor even though I’ve never repaired a hub motor in this way before. Our org has a very limited budget so anything that can get me out of buying a whole new motor and having it laced into the rim is preferable.

I have combed ES as well as Reddit and my best googling and have not run into this issue anywhere else.

 

[offGridDownUnder]

the e-bike lending library that we are building for charity work.

it will speed down the road just fine on either PAS or throttle but the moment you stop giving it juice it will motor brake and throw an error 21 and won’t let you throttle again until it has come to a complete stop.

Summarising:

1. It works as expected from throttle or PAS.
2. Releasing throttle or ceasing pedaling invokes behaviour that matches motor braking.
3. No further actions will exit motor braking until completely stopped (motor not turning).
4. Once fully stopped, normal behaviour resumes (except repeating the above problem).

Yes, it sounds like regenerative braking.

1. When you turn the motor by hand (no power) does it exhibit free-wheeling in one direction? Is the motor itself mechanically locked - this is separate from the sprocket cassette free-wheeling - many of those have their own freewheel.
2. Do you happen to know from other sources if this motor is supposed to freewheel or supposed to have a locked clutch to provide regenerative braking? Online research, manuals etc.
3. Given your 'lending library', do you have other motors to try substituting in to narrow the question to 'motor' or 'something in the rest of the set up'?

 

[HardWaterATX]

1. When you turn the motor by hand (no power) does it exhibit free-wheeling in one direction? Is the motor itself mechanically locked - this is separate from the sprocket cassette free-wheeling - many of those have their own freewheel.
2. Do you happen to know from other sources if this motor is supposed to freewheel or supposed to have a locked clutch to provide regenerative braking? Online research, manuals etc.
3. Given your 'lending library', do you have other motors to try substituting in to narrow the question to 'motor' or 'something in the rest of the set up'?

1 and 2. I don’t think so. It’s not as bad as when it’s powered up but when I suspended the rear ended and pedaled I could hear the sun and planetary gears which shouldn’t be the case on a geared motor.

3. The odd size of the rear wheel (22” I believe) will make subbing another wheel difficult and necessitate controller change as well most likely.

 

[gromike]

Radwagon 4 is a geared hubmotor, so no regen. With the 22" tires it's kind of a problematic ebike in the Radwagon line up.
That said, I'd closely inspect the cable into the hub motor and then maybe replace the controller (and display), depending on if Rad did a proprietary thing with the battery.

 

[HardWaterATX]

Radwagon 4 is a geared hubmotor, so no regen. With the 22" tires it's kind of a problematic ebike in the Radwagon line up.
That said, I'd closely inspect the cable into the hub motor and then maybe replace the controller (and display), depending on if Rad did a proprietary thing with the battery.

That’s what I’m saying, it’s a geared motor but it’s not freewheeling internally. I’ve already replaced the display, controller and inspected all the wiring. Regardless, none of those would make the motor behave this way.

I know geared motors use some kind of clutch and that there has been some people fusing theirs shut so that a geared motor behaves like a direct drive. This seems like that but derogatory and not playing right with the controller

 

[stancecoke]

This seems like that but derogatory and not playing right with the controller

The Radwagon 4 uses a Lishui controller and a display with 5s protocol. Error 21 means "abnormal current", so this could match the unexpected regen issue. You could flash the EBiCS firmware to the controller, that is able to control regen and will throw no error.

 

[HardWaterATX]

. You could flash the EBiCS firmware to the controller, that is able to control regen and will throw no error.

The larger issue would be that I still have a geared motor that shouldn’t even be able to do regen. The resistance when it’s faux braking is much higher than when it’s unpowered so something is going on there too.

After sleeping on it I’m thinking I need to crack the motor open, but I’m not finding anything about if it’s even possible to repair the clutch.

 

[stancecoke]

but I’m not finding anything about if it’s even possible to repair the clutch

Often the freewheel is integrated in the planetary gear carrier and available as spare part.

 

[99t4]

At this point consensus is that the (geared motor) clutch is locked. This has been reported here, often caused by rust. Was this bike exposed to much water? Otherwise part of the clutch mechanism can deform from overstress.

You may be able to free it by holding the bike with the rear wheel in the air and running as fast as you can, and dropping the rear wheel back on the road to jar the clutch loose.

I kind of like member stancecoke's proposal in post #6 above. The added regen braking might be a benefit. I love that feature that's standard on my Radwagon v.1 (dd hub). Of course, that may also free up the stuck clutch.

If you have a 20" wheel you could substitute that as a test.

 

[HardWaterATX]

At this point consensus is that the (geared motor) clutch is locked.

you’re right about that. As to the wheel drop fix I think I’m going to opt to crack it open and see if I can clean up the clutch or find a replacement. I’ve seen this reported from a fella who did the clutch mod that the braking force is very dramatic. Without some kind of e-coasting algorithm in the controller (well outside my wheelhouse) you would essentially have to be throttling all the time or the motor brings your speed down quick. That is the downside of the sun and planetary gears when the ratio is reversed and there are a lot of failure points as they aren’t designed for those kinds of forces.

 

[99t4]

That is the downside of the sun and planetary gears when the ratio is reversed and there are a lot of failure points as they aren’t designed for those kinds of forces.

Doesn't seem so bad, this modification been done purposefully several times before, Grin even sells a clutch-locked version; their GMAC rear geared hubmotor.

 

[HardWaterATX]

Welp for lack of having a cassette lock ring removal tool that could get around the ligo style connector I opted to cut a small notch in the largest gear so I could remove the motor cover and woweee what a lot of corrosion. This bike did indeed see a lot of weather. I’m going to attempt to remove the clutch/planetary gear carrier to see if it can be repaired but it’s looking grim.

This deal keeps getting worse all the time

 

[99t4]

Are there any other parts of the bike showing signs of above average corrosion?

 

[E-HP]

Welp for lack of having a cassette lock ring removal tool that could get around the ligo style connector I opted to cut a small notch in the largest gear so I could remove the motor cover and woweee what a lot of corrosion. This bike did indeed see a lot of weather. View attachment 383569I’m going to attempt to remove the clutch/planetary gear carrier to see if it can be repaired but it’s looking grim.

This deal keeps getting worse all the time

Looks bad, but at least the windings aren’t cooked and the gears look intact. If you can’t source replacement parts, then maybe you could keep the bike for parts, or until you find a trashed bike with a good motor for cheap in the future.

You could try squirting it down with WD40 and let it soak in, then see if the clutch pawls get unstuck, without taking apart further. It might be worth it to see if there’s hope first, before taking it all apart.

 

[HardWaterATX]

Are there any other parts of the bike showing signs of above average corrosion?

Not so much, the controller looks like it has sun damage so I’m suspecting that the lack of obvious corrosion has to do with the all of the bolts and such being high quality stainless and the frame itself being of course aluminum. Maybe just the seats were covered?

Anyways this is all surprising because the bike looks to lightly used overall with little wear.

 

[HardWaterATX]

You could try squirting it down with WD40 and let it soak in, then see if the clutch pawls get unstuck, without taking apart further. It might be worth it to see if there’s hope first, before taking it all apart.

I’m going to pull the clutch out and soak it in evaporust then degrease and see how it all goes.

 

[E-HP]

I’m going to pull the clutch out and soak it in evaporust then degrease and see how it all goes.

A squirt of WD40 an hour before attempting to pull it off might still be a good idea. At least that's what I always tell myself after the fact when dealing with rusty parts.