It is a 120VDC system and was limited in speed but was supposed to go 50 MPH with the safety disabled. They had forty 12V batteries with each set of ten batteries paralled together. They had fully adjustable coil overs and 4 wheel independent suspension with 4 wheel hydraulic proportioned disc brakes.
50 mph is awfully fast for a golf cart, even for a Planet G-4, have you had it to that speed?
As HRC mentioned above, the Southern California company went out of business in the mid 90's.
Planet Electric didn't reinvent the wheel here, just modified it a little. It will likely have been built on an Yamaha, Ezgo or CC chassis. If you post up some detailed photos, it shouldn't be hard to figure out.
What problems are you having?