Afternoon

I have a 36v battery and the above-mentioned controller is set to the correct voltage in P3 but I am quite often switching the controller on and getting the flashing empty battery signal despite the battery being fully charged. Checked connections and one green wire was disconnected but when connected that seemed to cause the motor to hum so disconnected,,,checked the rest and seems all fine. Switched back on and the battery is now showing as full but use of the throttle immediately replicated the issue. Double clicked the centre button and shows the voltage flicking around 25.5-27.6 and I believe it needs to be above 29 to function? Reset again and instructed wife to not use throttle but it didn't like being unplugged. Should I invest in a new controller setup?

Thanks for taking the time to ready

Dan

Many controllers that use the S866 have the self-learning wires. Does yours have them and if so, are they connected or disconnected?

What's the history? Nothing happens for no reason. What change brought about the issue?

What do you mean by "the throttle didn't like being unplugged"?

Edited April 30Apr 30 by D8veh

57 minutes ago, D8veh said:

Many controllers that use the S866 have the self-learning wires. Does yours have them and if so, are they connected or disconnected?

What's the history? Nothing happens for no reason. What change brought about the issue?

What do you mean by "the throttle didn't like being unplugged"?

Thanks for the reply

Self learning wires - I wouldn't know - there are a couple that are disconnected such as the green one but that didn't seem to go well. Is there a simple way to identify if I have those and if so what advantages are there? I will research anyway.

Agree re history - all was fine until about 3 weeks ago when the same thing happened - the first since purchase. Possible condesation issue with the display as wife had covered the screen in clingfilm to act as a water cover.

After the intial reset the battery display seemed fine but as soon as I turned the throttle, the issue happened immediately, so I traced the cable and unplugged it but then I couldn't seem to get the controller to connect again.

22 minutes ago, Tefoonez said:

Thanks for the reply

Self learning wires - I wouldn't know - there are a couple that are disconnected such as the green one but that didn't seem to go well. Is there a simple way to identify if I have those and if so what advantages are there? I will research anyway.

Agree re history - all was fine until about 3 weeks ago when the same thing happened - the first since purchase. Possible condesation issue with the display as wife had covered the screen in clingfilm to act as a water cover.

After the intial reset the battery display seemed fine but as soon as I turned the throttle, the issue happened immediately, so I traced the cable and unplugged it but then I couldn't seem to get the controller to connect again.

Does the pedal assist work properly, or do you only use the throttle?

Pedal Assist is non functional now after a lbs attempted some repairs but the crank was not reconnected so currently just the throttle

OK, the first thing to check is that the motor connector down on the chainstay by the motor is ALL THE WAY IN AS FAR AS THE LINE, not just in tight. Please confirm that you can see the line and the outer reaches it. If it's not in far enough, you can get the problem you describe, though there are other potential causes.

At the moment, I'm not sure what you're saying about your bike. It has no pedal sensor and it stops working as soon as you operate the throttle. How does it work without using a pedal sensor or throttle in order to stop working when you operate the throttle?

Also, you're not giving us much about the history. Why was it in the LBS for them to break the pedal sensor? What were they repairing, and did it work when they gave it back? Please give proper details so that we can help you. Please also give us some details about your bike. What is it? What motor, controller (max current) and battery does it have?

12 hours ago, D8veh said:

OK, the first thing to check is that the motor connector down on the chainstay by the motor is ALL THE WAY IN AS FAR AS THE LINE, not just in tight. Please confirm that you can see the line and the outer reaches it. If it's not in far enough, you can get the problem you describe, though there are other potential causes.

At the moment, I'm not sure what you're saying about your bike. It has no pedal sensor and it stops working as soon as you operate the throttle. How does it work without using a pedal sensor or throttle in order to stop working when you operate the throttle?

Also, you're not giving us much about the history. Why was it in the LBS for them to break the pedal sensor? What were they repairing, and did it work when they gave it back? Please give proper details so that we can help you. Please also give us some details about your bike. What is it? What motor, controller (max current) and battery does it have?

Appreciate the time, can't currently check as wife is using bike (as a bike!) for work so will be Sunday basically but thanks re first tip, I will certainly check that.

Info: Cannondale Adventure 1 bike, with Hailong 36v battery, 250w motor, controller as you know. LBS had the bike as wife came off so decided best to get it serviced - there was an issue with one of the cranks (thread) but it appears in investigating the worker has done something that stops the pedal assist - damn bike weighs a ton so hard to see under! Will also look and post a picture.

So it seems as if my wife has been using it as a throttle assist method bike, so pedal as normal, give a boost especially when going up hill or into the seemingly neverending wind, and then back to no throttle assist when down hill or wind.

Just to follow up on this one have tested the 36v battery with a multimeter and it’s showing 40.9 - is that correct or is it in fact a 42v battery? I cannot see from the battery.

I have put the controller into p3 and it’s at 36v and p15 is set at 29v as the minimum. When I see the voltage on the display it’s bouncing around between 24 and 27 but under 29 hence not working. I can’t figure out how to post the video on my phone here but what does this tell anyone? Controller broken?

Thanks

Dan

There are no 42v batteries, a battery is sold as a nominal voltage battery,

A 36v battery is a standard voltage, typically is has a usable voltage range of 32v - 42v.

40 .9V is a bit low, so the battery may not be fully charged or if it is fully charged then is likely out balance.

29v is really too low for a 36v battery, one is better off with a 32v bottom cut off so as not to discharge cells too deeply.

So I should get into p15 and up the cutoff to 32?

Still , I don’t understand why the controller is showing random sub 28v values when it’s definitely not

You heed to inspect all the wiring, especially the motor cable, to find out if any wire got damaged during the fall or when the bike shop attempted repair. It's probably easier to invert the bike to do the inspection.

Edited Monday at 19:551 day by D8veh

1 minute ago, D8veh said:

You heed to inspect all the wiring, especially the motor cable, to find out if any wire got damaged during the fall or when the bike shop attempted repair. It's probably easier to invert the bike to do the inspection.

Happy to do that, is there a website I can see a plan of connecting so I can check against what’s there and what should be? Bike was purchased as a complete build so I don’t have schematics for the installation

19 minutes ago, Tefoonez said:

IMG_5265.mov

The wiring looks OK, but the pedal sensor doesn’t look right. There should be an even 1mm gap between the sensor and the magnet disc. See if you can bend the sensor and/or wiggle the disc back into position. You should alsoo check where all the wires connect to the controller, especially the motor wire connection to make sure that there's nothing melted there.

On 11/05/2026 at 21:34, D8veh said:

The wiring looks OK, but the pedal sensor doesn’t look right. There should be an even 1mm gap between the sensor and the magnet disc. See if you can bend the sensor and/or wiggle the disc back into position. You should alsoo check where all the wires connect to the controller, especially the motor wire connection to make sure that there's nothing melted there.

Thanks for the advice on that, will give it a go asap. Wiring all looks normal to me.

What voltage rating does the controller have on it ?