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Can magnetic fields affect an ebike controller?

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    Can magnetic fields affect an ebike controller?

    I have this bag that attaches to my bike magnetically. It's the kind that goes on the tank of a crotch rocket. I've had it on the bike for about 150 miles, but all of a sudden my bike is freaking out. It either has no throttle at all or it accelerates uncontrollably at full power without my even touching the throttle or pedals at all. It's like it has a mind of its own. Quite dangerous actually. The brakes still activate the motor cut off, but as soon as I let off of it, it's full-throttle uncontrollably. The bike is only 3 months old. Only rode it about 5 times and less than 300 miles. It's Stealth Bomber clone with a Sabvoton controller and Panasonic battery. It claims to be 72v and 8000w. Do you think magnetic fields can trip out an ebike controller? Let's say you stuck a magnet right on the case of the controller hypothetically, is it possible that this can cause the issues described above? The bikes battery case that the magnet is attached to is like centimeters from where the controller is mounted with only the metal battery case in between. Yes, I've taken the case off and the problem persists.

    EMI can mess up any electronics if the source is strong enough. I watched a guy sit his Blackberry (in it's leather holder with a magnetic closiure on the flap) on his laptop, right over where the HD is and the magnet in his holster caused his HD to fail. I am not saying this is your cause, but it is possible magnets if placed at the right location "Could" cause an issue.


      Most throttles are hall sensors (the throttle moves a magnet) so conceivably if you get a strong magnet near the throttle you can cause a throttle signal - it would have to be pretty close to the throttle

      Many motors have hall sensors in the stator to sense the motor shaft position to feed to the controller but it would take a very strong magnet very close to the motor and it would most likely jut cause the motor not to run or run very poorly

      The controller doesn't care about DC magnetic fields (like a magnet) unless you are talking about magnets nearing MRI machine strengths

      Magnets and EMI have pretty much zero do do with each other unless the magnet is moving very, very quickly - not in any realistic sense from a tank bag


        Only thing I could think of is if there was a relay on the controller for some reason and then it would have to be a fairly strong magnet in just the right/wrong spot. And even then I would think it would not cause it to do strange things, I would expect more of a stuck on or off sort of thing.


        • AZguy
          AZguy commented
          Editing a comment
          Very, very unlikely it has anything to do with a relay - the relay would have to be open and the magnet very close, very powerful and at exactly the right orientation relative to the relay... I've never heard of a magnet affecting a relay and regardless it's extremely unlikely there are relays in anything on these bikes, they just don't bring anything to the table...

          Hall sensors are really the only thing that are going to be terribly susceptible to magnets and even then the only ones I would expect to even potentially be affected would be the throttle or brake sensors and the magnet would have to be close