Using a 48V YK42-4 controller I picked up from Rob, four 12V 12AH Max Life eBay batteries, and new red throttle/grips the build was ready to go.
Mounting the extra battery was pretty easy. Mounting the top batteries sideways I was able to lift the front battery up using a piece of 2X4, the rear battery was lifted a bit as well in order to avoid bending the battery tray. I used industrial strength velcro to stick the wood to the bike and the batteries to the wood spacers.
I used copious amounts of zip ties to secure the batteries in place. I also used velcro and zip ties to mount the controller.
The white connectors with smaller gauge wire are for the charge ports.
I mounted a 300A battery disconnect inside the fake gas tank like Rob (great idea!), along with a 130A volt/amp meter. While the whole process is straightforward, it was many hours of cutting, crimping, and heat shrinking to get everything wired up nicely. But well worth it!
Since I have plenty of 24V chargers but no 48V, I just added another charging port next to the stock one and have each charging two of the batteries. I had to cut most of the top of each of the plastic side cases to get them to fit, but only a little of the wiring near the back is visible.
The good news, the volt meter worked great and I saw that on full throttle startup I was pulling 66A, which leveled out to 26A as I reached a nice cruising pace. 21 MPH on flat road, 23 on a slight downhill. About what we expected. The new controller definitely has more grunt than the stocker, but not uncontrollable for my 8 year old.
The bad news, the volt meter stopped working after about 5 minutes, LOL. Oh well, at least the controller has an LVC, so no worries. I believe the issue was my fault. I wired the meter between the controller and motor since I wanted to see what was actually going to the motor and not what was being potentially wasted in the controller. This meant that when off the throttle, the meter would switch off. I think the on/off/on/off/on/off is what killed it so quickly. On the next build I will mount it between the batteries and controller.
48V Razor MX500 w/ yk42-4 50A controller
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