Deadly Sur-Ron problem?

[Sheda]

Hello! I just recieved my Used Sur-Ron 2018. I did a few very short trips around the yard and it was ok. My brother came over today to look at it and he had a few trips in our yard aswell. I jumped on the bike and everything was fine, i did a high speed run and then when i went to turn around it just took off and landed maybe 4 meteres away from me with a broken foot peg bracket. Otherwise fine. I picked it up and went to drive back slowly, then it just kept going faster and faster and i could not turn it off, i started braking cause i was too scared to let go and turn the key, and it eventually stopped, i chewed thru the whole braking pad.

I went on the gravel, grabbed the front brake and tried giving it a little bit of gas, seemed fine untill i gave it half throttle and then it wen full speed again. I turned it off with the key and rolled it inside.

I started looking for what might be the problem. I started with the throttle and saw that the throttle wire was only hanging on by two threads. Great i thought, ill just need a new wire....

So i did some other maintance on the bike, chain, brakes and belt tension.

After the chain and belt was tensioned i decided to just give it some throttle and see and hear if everything was ok. Its on a rest and the back wheel is in the air just in case.. I have now removed the wire to the throttle and im just twisting the speed controller below the motor. It worked fine the first few times but then it suddenly started to run at low speed by itself.

I turned it off and then back on, now the motor wont go at all.. Tried turning it on and off a few times and suddenly it went to max speed. It did not sound good for the sprocket or what ever it was that made that loude clonk noise. I left it there and now im desperate for some answers here cause i can't find anything on the internett about Sur-Rons taking off like this..

[Tommycat]

Hi Sheda,
And welcome to the forum! :-)

I'd first start on the safety side of your issue of erratic throttle control. That being to get your brake cut off sensors working properly. By that they should disable power to the motor when activated. That corrected, move on...

https://electricbike.com/forum/forum/knowledge-base/surron/67934-sur-ron-modifications-adjustments-tips-tricks?p=74762#post74762

So it sounds like you have adjusted the throttle's mechanical cable properly...

I would then look at the throttle's speed adjustment controller for it's correct output operation...

https://lunacycle.com/sur-ron-replacement-speed-adjustment-controller/

From the cost of a replacement, I'm speculating that it is a hall sensor type throttle controller. As such it should output a variable voltage of ~.8 to ~ 3.6vdc. Throttle closed to WOT.

I do know that with a hall sensor throttle, that it will go to a higher motor output if ether..

1) The ground leg to the sensor is damaged, poor connection, or broken.
2) Or the output wire is shorting to the input wire. (5vdc regulated)

So close examination of it's wiring is a must.

For information on how to fully troubleshoot a typical hall sensor throttle go here...

https://electricbike.com/forum/forum/kits/golden-motor-magic-pie/70584-guide-to-hall-sensor-throttle-operation-testing-and-modification

To much? Perhaps just replacing that relatively inexpensive part, may be a good consideration.

For more Sur-Ron information see...

https://electricbike.com/forum/forum/knowledge-base/surron

Glad to hear no one got seriously hurt! Any questions, feel free to ask.



Regards,
T.C.

[Sheda]

Hi Sheda,
And welcome to the forum! :-)

I'd first start on the safety side of your issue of erratic throttle control. That being to get your brake cut off sensors working properly. By that they should disable power to the motor when activated. That corrected, move on...

https://electricbike.com/forum/forum/knowledge-base/surron/67934-sur-ron-modifications-adjustments-tips-tricks?p=74762#post74762

So it sounds like you have adjusted the throttle's mechanical cable properly...

I would then look at the throttle's speed adjustment controller for it's correct output operation...

https://lunacycle.com/sur-ron-replacement-speed-adjustment-controller/

From the cost of a replacement, I'm speculating that it is a hall sensor type throttle controller. As such it should output a variable voltage of ~.8 to ~ 3.6vdc. Throttle closed to WOT.

I do know that with a hall sensor throttle, that it will go to a higher motor output if ether..

1) The ground leg to the sensor is damaged, poor connection, or broken.
2) Or the output wire is shorting to the input wire. (5vdc regulated)

So close examination of it's wiring is a must.

For information on how to fully troubleshoot a typical hall sensor throttle go here...

https://electricbike.com/forum/forum/kits/golden-motor-magic-pie/70584-guide-to-hall-sensor-throttle-operation-testing-and-modification

To much? Perhaps just replacing that relatively inexpensive part, may be a good consideration.

For more Sur-Ron information see...

https://electricbike.com/forum/forum/knowledge-base/surron

Glad to hear no one got seriously hurt! Any questions, feel free to ask.



Regards,
T.C.

Hello. Thanks for the help. I ended up replacing the Speed controller and i went for a test ride. All good, the next day i dressed up and headed to the woods. After 3 minutes on a stretch it started going by itself again. I twisted the key and it stopped. When i went to turn it on again the motor didnt go. No matter what it didnt start again. I went home unplugged a bucnh of things and plugged them back in again. Still nothing.. Any suggestions?
All sensors have been removed, even the fall sensor.

[paxtana]

Have you asked about it from whoever sold this used bike to you?

I would probably replace the entire throttle assembly, personally. And if that doesn't work, a new controller.

[Tommycat]

I'd be double checking the output voltage of the speed controller and your cable adjustment and operation. Most controller's will "lock out" if the throttle voltage is seen as too high on start. Perhaps the cable is binding, or holding it open a bit. Not returning to home or fully closed position. (~.8vdc to ~3.6vdc)

[Sheda]

I'd be double checking the output voltage of the speed controller and your cable adjustment and operation. Most controller's will "lock out" if the throttle voltage is seen as too high on start. Perhaps the cable is binding, or holding it open a bit. Not returning to home or fully closed position. (~.8vdc to ~3.6vdc)

Hey, glad you mentioned it. I was just outside and did some measuring. What i got from measuring at the speed controller is that it was at .635. So, its too low? Any clue ?

[Sheda]

Have you asked about it from whoever sold this used bike to you?

I would probably replace the entire throttle assembly, personally. And if that doesn't work, a new controller.

Hey. I checked the voltage of the speed controller and it was at .635v no matter what.. I just changed the throttle wire and the speed controller for a new one..

[paxtana]

The throttle wire is not the same thing as the throttle assembly

[Sheda]

Have you asked about it from whoever sold this used bike to you?

I would probably replace the entire throttle assembly, personally. And if that doesn't work, a new controller.

How to i comment on your comment, or tag you in the comment..?

But, what do you mean then? It doesnt matter if the wire is attached or not, when i twist the speed adjustment controller by hand it still doesnt work.

[paxtana]

There are three small dots on the right hand side you can click and there is a link to comment which will drop your comment below mine.

Did you replace this? https://lunacycle.com/sur-ron-replac...nt-controller/

[Sheda]

Have you asked about it from whoever sold this used bike to you?

I would probably replace the entire throttle assembly, personally. And if that doesn't work, a new controller.

Hmm, sorry, i cant find it.. And yes, thats the one i replaced. Thats where im measuring and getting too low voltage. I think theres a component in the controller thats supposed to supply it with 0.8-3-6v or something. Im worried that component is broken and theres no way to replace it i guess since the controller is filled with that black liquid.

[Tommycat]

The main controller supplies the speed controller AKA throttle with 5 vdc power on one wire, with the ground or battery negative being another wire. It takes this input voltage, and outputs it on the last wire back to the controller to tell it what speed to go.
An output reading stuck at .635 is a problem. So keeping your test lead (black) on the above mentioned ground wire. Put the meter's red test lead on the 5vdc input wire to verify that the voltage is indeed there.

[Sheda]

The main controller supplies the speed controller AKA throttle with 5 vdc power on one wire, with the ground or battery negative being another wire. It takes this input voltage, and outputs it on the last wire back to the controller to tell it what speed to go.
An output reading stuck at .635 is a problem. So keeping your test lead (black) on the above mentioned ground wire. Put the meter's red test lead on the 5vdc input wire to verify that the voltage is indeed there.

Thanks for the reply. So i went and did some more testing after reading your response.

There are 3 wires coming from the speed controller. I measured between all of them and the i got .700, then 0.635 and then .065. So no 5vdc here. Then i took my black test lead and put it on the negative wire that goes directly to the controller. Now i got 4.80vdc on two of them and 0.65 ish on the last one.

On the Sur-Ron controller everything is covered in epoxy so i cant really test further than the wires coming out of it.

But is one of the wires going into the speed controller supposed to be a pure negative lead? If so, sounds like i dont really have that.

[Tommycat]

But is one of the wires going into the speed controller supposed to be a pure negative lead? If so, sounds like i dont really have that.

Yes, one of the wires is a pure ground or battery- connection. Sounds like you isolated the problem! Well done! :-) This loss of hall effect throttle ground would fit your problems description well.

So all you have to do is wire the throttle's ground wire to another common ground. As it's power requirements are very low ( less than 10mA ) you can grab any ground that may be convenient. This would include the brake switch ground or one of your other sensors... or even the battery ground ( - terminal) which ever is easiest.

I don't think I'd bother with the controller potting. :-/

And you may want to do a quick test first, jump the correct throttle ground wire to the batt ground, or again what ever is easiest, and test for operation. (Make sure the throttle wire your jumping to is the correct ground wire.)

[Sheda]

Yes, one of the wires is a pure ground or battery- connection. Sounds like you isolated the problem! Well done! :-) This loss of hall effect throttle ground would fit your problems description well.

So all you have to do is wire the throttle's ground wire to another common ground. As it's power requirements are very low ( less than 10mA ) you can grab any ground that may be convenient. This would include the brake switch ground or one of your other sensors... or even the battery ground ( - terminal) which ever is easiest.

I don't think I'd bother with the controller potting. :-/

And you may want to do a quick test first, jump the correct throttle ground wire to the batt ground, or again what ever is easiest, and test for operation. (Make sure the throttle wire your jumping to is the correct ground wire.)

OK so I went out to try this. But now when I measure between all the three wires to negative I get 4,8 4,8 and 3,7v?? I don't understand.

When I tried putting one of the wires directly to negative the motor started going and didn't stop till I turned the key or pulled the one I think is the positive (red/white).

[Tommycat]

To recap...

After running your jumper with the battery off...

Measuring from battery's negative terminal with the battery on: (or the ground that the jumper is connected to)

Throttle's Red/White (your call) wire is 5vdc (4.8vdc) input from controller
Throttle's ???? color output wire is ~.8 to ~3.6 vdc. (may go to 4.2vdc) to controller depending on throttle position.
Throttle's (Speculating Black) wire goes to 0vdc or batt negative. This should measure 0vdc. Thinking this is the one that at first had the .65vdc reading... You may want to disconnect this from the original controller wire ground just in case its shorting out internally to something.
Is this the wire you jumped to?

retest.

Not sure, or something doesn't sound right, ask before you try.

[Sheda]

To recap...

After running your jumper with the battery off...

Measuring from battery's negative terminal with the battery on: (or the ground that the jumper is connected to)

Throttle's Red/White (your call) wire is 5vdc (4.8vdc) input from controller
Throttle's ???? color output wire is ~.8 to ~3.6 vdc. (may go to 4.2vdc) to controller depending on throttle position.
Throttle's (Speculating Black) wire goes to 0vdc or batt negative. This should measure 0vdc. Thinking this is the one that at first had the .65vdc reading... You may want to disconnect this from the original controller wire ground just in case its shorting out internally to something.
Is this the wire you jumped to?

retest.

Not sure, or something doesn't sound right, ask before you try.

I think I put the sensor wire to ground when it started going by itself. I have no connected a wire directly from the negative pole to the black wire on the contact of the speed controller. And it works flawlessly. I'm gonna let it run on the bench for sometime just to see it holds up but definitely think this is it! Thank you so so so much!