E-Z connect charger (was charging at hom

[LEE A HART <XURQ03A@PRODIGY.COM>]

Conductive

Low voltage, low current systems are easy. UL considers anything below 30
volts, 8 amps, and 200 watts to be a Class 2 circuit which is intrinsically
safe (not a shock or fire hazard). 200 watts will charge a 12v 100ah battery
in 8 hours. So an exposed connector is fine for an E-bike or Electrathon type ve
 hicle.

Higher voltages and currents need to be insulated to prevent inadvertent
contact. Fundamentally, you need to arrange things so no one can touch live term
 inals.

It is good practice to arrange things so the charger won't turn on unless it
senses voltage from the car's pack. You also want to have a fuse in both
charger and car to limit current in case of a fault. If your car's charging
terminals are connected to the battery and exposed, use a switch or relay that
only connects power to them when the charger is plugged in. This same switch
or relay can also disable the car's controller.

Inductive

GM thinks they have a patent on inductive charging, but it's been around a
very long time. The Braun electric toothbrush for example, is a high frequency
inductively coupled battery charger that's been on the market for many years.
And there are examples of 60 Hz and 400 Hz inductive couplers that go back
before WW2.

All you need is a transformer cut in half. One half mounts in the car, the
other half at the end of a cord. Put the two halves of the core together, and
turn on the juice. The magnetic force will lock them together (each half
transformer is exactly like an electromagnet).

60 Hz transformers are heavy; about 40 lbs per KW. If half of this is in the
car, you still have a 20 lbs lump at the end of the cord. The best you could
do (easily) is put all the "E" laminations and secondary winding in the car,
and the "I" laminations and primary on the cord. This would still make the
cord end weigh about 10 lbs per KW. This is why GM went to a high frequency
transformer; to get the weight down.

However, a 60 Hz half-transformer approach could be very effective if mounted
on the floor under the car. You drive over it, turn on the juice, and the half
transformer on the floor will leap up and connect to the half transformer
under the car.

Lee Hart                     If you would not be forgotten
4209 France Ave. N.          Soon as you are dead and rotten
Robbinsdale, MN 55422 USA    Either write things worth the reading
phone (612) 533-3226         Or do things worthy of the writing
e-mail XURQ03A@prodigy.com   (Ben Franklin, Poor Richard's Almanac)
E-Z connect charger (was charging at hom