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
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