M. G. wrote:
What would it take to make any charger isolated?
It requires an isolation transformer.
You can use a big 60Hz transformer ahead of any charger to isolate it.
As noted, these tend to be rather big and heavy; on the order of 10 lbs
per kilowatt. New ones are expensive (cost of materials), but they can
often be found used at low prices.
As frequency goes up, the size and weight and cost of the transformer
goes down. Aircraft use 400 Hz power for exactly this reason. Switchmode
power supplies run at even higher frequencies, well up in the KHz range,
to go even further.
However, high frequency transformers are a lot harder to design and
build. When your only power source is 60 Hz AC, you also need extra
equipment to a) rectify it to DC, b) convert the DC to high frequency
AC, c) run it through the transformer for isolation, and d) turn the
high frequency AC output back into whatever voltage you need for
charging. Steps a) and d) are the only steps that are done in
conventional non-isolated chargers. Adding isolation can easily double
the cost of the charger.
--
The storage battery is one of those peculiar things which appeals to
the imagination, and no more perfect thing could be desired by stock
swindlers than that very selfsame thing. Just as soon as a man gets
working on the secondary battery it brings out his latent capacity for
lying. -- Thomas A. Edison
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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