I took the wires the go to the original batteries connected them through a switch, between battery and module, and added a second switch connected them to the same wires for the 18V. When 12V is on 18V has to be on off position and when 18V is on 12V has to be in off position.
I run a 24v lithium ion and 24v controller on my son’s MX125. Motor gets hot but hasn’t burned out yet.
I’m running stock controller and just recently added a craftsman 20v battery from my power tools. So far so good nothing burned
The power tools came with two batteries, so they charge pretty fast and are easy swap
Pretty smart how you built the switches that away you don't run up the original battery
Best mod I've seen so far
My son has one but it won’t crank what could be my problem
So if he was riding on 18v and flipped the 12v switch...would it then become 30v? That may burn the motor out, but also may be very fast haha.
I would suspect speedup and burnout, I plan to eliminate one switch and put in a relay system instead just to prevent this.
only if they were wired in series.
How did you connect the external battery to the original bike? What wires did you splice
I took the wires the go to the original batteries connected them through a switch, between battery and module, and added a second switch connected them to the same wires for the 18V. When 12V is on 18V has to be on off position and when 18V is on 12V has to be in off position.