My RC ebike -Matt Shumaker Astro3220- with a mind of its own

[Jonas H]

First a preview of my bike:

Bike: Specialiced S-works (1998)
Motor: Astro flight 3220
BEC: Dimension Engineering VHVBEC
Servo tester: Astro Flight Servo Tester
Battery pack: 12S2P Turnigy Lipo 20ah 50V (With balancers and charger from Jozztek)
Drive system: DaVinci (Matt Shumaker)
ECS: Castle Creations HV160 (rev 2)
Battery case: Toppeak MTX TrunkBag EX
Monitoring: Cycle Analyst
Thruttle: Magura throttle

Setup was done following Matts guide here: http://endless-sphere.com/forums/viewtopic.php?f=28&t=12196

Some pictures:









The issue:
The bike has been running perfectly for 4 battery-charges (300km), but now I believe the system has gotten a mind of it's own... After a 20 min drive in some moderate rain the throttle didn't respond well. I checked the ESC and servo tester, but the weren't wet and seemed fine. After this ride the bike started to act on its own. Now the bike suddenly accelerates to max speed (60km) in seconds when I'm not turning the throttle. 2 days ago I almost was thrown of the bike as it suddenly accelerated when i was rolling slowly across the street.

I'm no expert, so I do not know where to start searching for the error.. Help would be appreciated!!

 

[nieles]

water could very well cause these kind of problems.

can you reproduce the incident? (on the bench or with the wheel in the air would be preferable) if so, you can measure the voltage from the throttle line to see if the problem is there, and then work your way to the controller.

do you have access to a oscilloscope?

 

[Jonas H]

water could very well cause these kind of problems.

can you reproduce the incident? (on the bench or with the wheel in the air would be preferable) if so, you can measure the voltage from the throttle line to see if the problem is there, and then work your way to the controller.

do you have access to a oscilloscope?

I have only done a small test, because it's a bit dangerous. I removed the chain and tested the throttle response for 10-15 min. without any issues. I hereafter took a test drive for 10-15 min. and experienced around 2-3 spontaneous accelerations. It might be a coincidence, but it seems like the error only occurs when there is resistance from moving the bike. I don't see that this difference should mean anything, but now you know.

I'm afraid i don't have access to or own a oscilloscope. Do you suspect the throttle is defect? I don't know the specs, but would expect it to be "water prof". It would be strange to make anything for a handlebar that could not take a bit of water.

 

[Voltron]

Mine did the exact same thing after a few rides, leading to some frantic plug pulling. It turned out to be a tiny pinch in the throttle wire midway down the bike, once I figured out the spot I could poke it with my finger and make the bike jump. Been running fine since running new wires the the same throttle... it was an eye opener though on how one tiny defect could make the bike jump to full power in an instant.

 

[visuthdy]

Jonas,
Sorry to go off topic. From your picture I see that you have A2Z disc brake adapter with disc break on Matt's sprocket adapter. Do you have disc brakes working? I have an old Specailized bike also and would like to put disc brakes using A2Z adapter. thanks.

 

[Psycholist666]

There's another way you could wire this up.... through the cycle analyst. I'm not sure which version you have there but all are capable of putting out the correct signals for R/C mode. Wire the throttle into the CA, select R/C mode and wire the HV160 inton the CA. You then have another set of variables to play around with via the CA. One thing that could be happening, although I haven't tried the HVBEC/servo tester set up myself, is RF interference to the servo tester. I rememeber in Matts video that he stresses the point about sheilding the circuit boards from RF, and maybe with even the tiniest bit of water this is what is happening??!! However I'm sure that a lotpeople tell you this - don't take an electric bike out in the wet!