While the content is a little old, I feel there is a lot to be learned from my first EV project.
I started with a GoPed ESR750EX a friend found on craigslist.
The first modification I did was larger batteries. The scooter was originally designed for 7ah (amp hour) SLA(Sealed lead acid) batteries, but the EX (extended range) version that I had was designed for 9ah batteries. This was not nearly enough so I put 12ah batteries in it, which required slight modification to make them fit.
With an increased range, I now wanted to increase the speed. To prepare for this increase in speed, I bought Kenda street tires, and Hayes hydraulic disk brakes for the scooter.
About this time, a member of GoPed Nation posted up beta signups for a larger motor for the scooter he called "The Torkinator". I was selected to be one of the beta testers for this motor, and received one about a month later. The motor alone brought my max speed up from around 20mph, to about 27mph(when geared more for speed). Still not satisfied, I started looking for more power.
This would come in the form of a new motor controller. The scooter was originally designed to run at 24v, with a roughly 30 amp continuous draw. This created around 750 watts of power, or roughly 1 horsepower. The new controller, a Kelly KDS48200 was rated for up to 48v, at 200 amps peak power, and 80 amps of continuous power. This means I could run at 3840watts continuously, and up to 9600 watts for a short burst. In horsepower, this is just over 5hp continuously, and almost 13hp for a short time. This was much more in line with the power I was looking for, but there was still a problem. The Torkinator I was using was only rated to spin at 6000rpm's, and at full speed, my new controller would let it spin at 7200rpm's. I contacted the creator of the Torkinator, and asked him to make a higher performance version, to which he kindly obliged. By the time this higher performance motor was out, the motor had left its beta stages, and was in full production, known as the T2. The higher performance version is the T2S.
After many hours of wiring, and custom fabrication the scooter was working, and nearly complete.
Here are a couple of pictures of the scooter during construction, though it has been significantly cleaned up since then, as well as a video. In the video, the camera is mounted to my scooter, and the rider and scooter in view are my friend, who took a slightly different approach to modifying his scooter. Needless to say, they are both very fast. In this video, we had speed limited in software to around 40mph(roughly 65% of the possibly power). I'm hoping to do a write up on his scooter soon.
I never got to ride with a fresh set of batteries, so I don't know the true range on a fresh set of batteries, but at speed, I could generally get about 3-4 miles of range, at roughly 40mph.
Unfortunately, I toasted my motor a few months ago by not breaking in the brushes properly, and damaged the commutator. It is fixable, but required new motor parts, and the commutator to be remachined smooth again.
This will eventually lead to the final phase of modification on this scooter... Lithium batteries. I will post up in the future as this idea comes to fruition, and the rebuild of the scooter in all of its glory.
For more reading, check out the build threads of how this thing was created:
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