I owned and drove a 1970's Aurenthetic mini bike

Back in 1973 I needed wheels to get to my College classes, then my work, and then back home for some sleep to do it all over again. I had classes during the week, but I had to work 7 days a week during the Silicon Valley employment boom.

As a married starving student, I had little time, or money. My research offered a new Honda trail 90 for $900, or an Electric Aurenthetic mini bike for about the same money. A trail 90 required a motorcycle licence, the Electric did not. Though 1970's just had a gasoline-crisis doubling the cost of gas, the cost of gas was very little back then when compared to today. Even so, work did not pay much so the cost of fuel, oil, and maintenance was important.

A local Aurenthetic dealer offer the standard mini bike model seen in the images on this page. One motor geared for a top speed of 15 MPH with a range of 35 miles. At an additional cost, the dealer offered a special modified version of his own design: Two motors geared together for a top speed of 35 MPH with a reduce range of 15 miles.

I choose the latter as all the time I save means more sleep for me (and of course it was more fun to ride). I found the on board battery charger only put 7amps into the two group 27 12V batteries. The charger was a dumb transformer type that tapered its output current quickly. This means an overnight charge may not be enough to fully recharge the battery pack.

I decided to buy a 110VAC Sears 20amp 12V charger. I took the charger apart and replaced the half-wave rectifier with a 40Amp full wave rectifier bridge. I used the center tap transformer lead to provide +12V  Ground  -12V.

The Aurenthetic's two 12V batteries are in series. The bike has a spring loaded right-hand grip for acceleration: Off, Low speed (one 12V battery), and High speed (both 12V batteries).

I connected  the charger up to charge both batteries at the same time and the center tap allows each battery to take a its own charge. Since low speed only uses one battery after use the batteries are unbalanced (one is more discharged that the other). The charger's configuration allows for a fast, full charge with both batteries balanced.

 Since twice as much power is being drawn from the transformer (24V at 20amps, vs its design of 12V at 20amps), I put a 110VAC fan on the transformer to keep it from over heating. Now I could leave the Aurenthetic charging unattended and get a full charge in a few hours instead of overnight.

I arranged to get permission to charge at the College while I attend classes, and to charge at work while I finish my shift. Each day I would be recharging the Aurenthetic three times: once at the College, once at work, and then while I slept. Because of this, I would use up the cycle-life of the batteries three times faster and would have to replace the batteries sooner than usual.

Even with the added cost of replacing the batteries, the cost of using the Aurenthetic was much less to operate and maintain that if I had chose a Honda trail 90 gasoline motorcycle. I kept the Aurenthetic for years afterward, but the shop I had bought it from stopped their support. When I could not get it repaired, I had to recycle the Aurenthetic. What a shame, it was a great bike and a kick to ride.