Motor cuts out

Off road all day

Active Member
Now this is what i'm thinking, i have a cutoff power brake lever, i actually don't need it It's all good without it.
I turned to the left sharply and the motor cut out quickly about 3 times, this puts the right handle brake cut off high. Any moisture can run down and cross the connection, cutting off the motor. Any guesses.
Its a frame mounted motor, the throttle, batt, controller are all separate. I have noticed the past week connecting the batt to the controller causes a small spark, pretty sure that's not good.
Moister in the controller? The connections where swapped out for much larger capacity ones.
Guaranteed all wires and connections far exceed factory specs.
With 3 days of wet snow on the way i have no way to test anything, definitely going to unplug the brake cut off first.


Well-Known Member
It's normal to get a spark when connecting the battery to the controller, but I don't think it is a good thing, especially with high AH batteries. What happens is that there are large filter capacitors on the controller that charge up to full battery voltage. While it's normal. maybe not so good. For sure, it will burn the contacts long term. I've started to see this with my cheaper battery chargers too.

Most commercial ebikes don't have this problem because their batteies have on/off switches. DIY guys see it.

If you are using XT90 connectors, those are available with anti-spark. There is a resistor that makes initial contact and in the milliseconds before the connector is mated, it has slowly charged up the input capacitors.

I'm seeing listings for XT60 anti-spark on ebay, but they appear to be scams.

Heres' a simple circuit that I built into a set of connectors to prevent spark for XT60 connectors. Plug it in and than close the switch, which cuts out the resistor.


I just grabbed an old switch to implement it.


Well-Known Member
I've eliminated the spark at turn on by just leaving the controller plugged in. I haven't charged my battery since December (now April 9), and it still is at half charge, to go by the yellow LED. A 17.5 AH battery used mainly to speed me across the 6 lane street at traffic lights, until I start riding to the summer camp this week. I do use electricity to speed though construction zones with the bike lane torn out.
How much did you pay for your controller? I have a $40 one and a free one that came with the $189 power wheel. Both cut out about the same time, a few minutes after I've started climbing hills one after the other. The first one the display blanked out, but the second one has yellow green red battery state LED's on the throttle, and those stay on after the motor cuts out.
As neither motor has a temp sensor, I believe that cutout a symptom of the controller overheating. I've had the first one apart, it does have a temp sensor. It also had no thermal connection between the FET mount bar and the expensive ribbed aluminum case. I corrected that. I haven't had the 2nd one apart yet, but it is cheaper than the first one and cuts out at the same point in my rides. The fourth or fifth hill. The first one is out at the summer camp and I never had a good battery out there yet to test it with after the heat sink mod.
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Well-Known Member
I take my batteries outside for charging. Just a cautious old Smokey the Bear here. Bikes stay inside.

If you had a $13 ebay wattmeter, you could run it on a 9V battery and it will record the minimum voltage. That might tell you what's happening when the controller goes blank.