Overheating controller


New member
Local time
12:39 AM
Oct 10, 2021
My controller melted the throttle/lcd control panel wires and pas wire. It looks like it was melting the motor wires that connect to the motor/battery. It's the green/yellow/blue wires and they all have holes on them from overheating. I'm going to put a 25 amp inline fuse on the wires that connect to the battery and see if that can fix the issue. I also have been reading that there are cooling systems for the controller? Don't know anything about how those work. If anyone knows how to keep your controller from frying, than please help me figure out how to cool it off. It rains everyday where I live and it's wrapped in a waterproof bag and I put trash bags over where the wires go into the bag to extra careful keep the water out. I'm sure since it gets no air it makes it worse. It's a 18 mosfet controller for 48v1500 amp bike motor.
Controllers NEED airflow. Especially so if reasonably high amp rating, like over 10. Fuse to the battery will do nothing, the controller acts sort of like a transformer,

just saw the 18 mosfet. MUST repeat MUST have airflow. Phase wires to the motor carry massive wattage, pulsed. PAS, throttle, LCD do NOT carry significant wattage and should never overheat. These are almost certainly affected by controller heat alone. Phase wires can generate significant heat independently, and OFTEN require replacement with heavier gauge wires. Especially on "inexpensive" kits. Phase amps and battery amps are NOT the same thing. Phase amps dramatically higher

I am amazed you have not blown the entire controller. One solution is to fill the box with potting compound, which essentially makes the controller itself waterproof. I live in rainy SW Florida, have a potted controller exposed to the elements for 8 years now, no problems. Mine is much, MUCH lower wattage, 36v, 8amp, probably could put this in a bag but no need.

Many stash the controller under the seat, to protect from rain. Mount high, ensure drip loops in ALL wiring, NO repeat NO exposed bare wiring, water can actually travel UPWARDS on twisted bare wire, "wicking". Capillary action. Many mount to the frame, to use the bike as a heatsink. Heatsinks on the case also help, BUT must have airflow.

Also, in case you don't know, any of those bare phase wires touch, you are going to need parts, lots of parts, some of them requiring difficult installation, or replacement of entire motor and controller. Also could cause motor to lock up totally at speed, which could be ..... unfortunate.