chris matzen <[EMAIL PROTECTED]> wrote...
> ...Just be sure you know what your alternator
> can safely put out while keeping you [sic]
> engine running, charging your battery,
> headlights on, and heater blower motor
> and windshield wipers running.
> ...
> ... if not properly dealt with, you can get
> yourself some unpleasant problems with
> overloaded alternator,dead battery easier
> than you thought, high-loss power wires,
> excessive EM noise, and maybe even a fire.
For those who'd like to skip the PhD program in auto electricals:
PBook power usage is in the range of 25-40 watts PEAK because that's the
capacity of the AC adaptors. Most all the electricity, in doing what
it's meant to, turns into heat. The books would get unbearably hot if
they used that on average; estimate more like 12 watts. If the inverter
is 50% efficient at that load, it'll take about 2 amps from the battery.
(Watts = amps * volts; 12 volts is the norm).
I'm not aware of car circuits fused (protected) for loads less than 5
amps; i.e., most any circuit will easily deliver that much juice. Make
sure that you don't use skinny wire from the lighter to the inverter.
And most batteries are rated for a couple dozen amp-hours, meaning if
your battery has at least half its capacity you have more than a full
day's use between charges. And alternators are capable of recharging a
perfectly dead battery, so your book is unlikely to make any noticable
impact at all when the car's running.
Cars have been a sewer of electrical noise, but I would guess the
inverter is the main source of EMF noise getting to the adaptor. A radio
or TV near the inverter might give you a clue if it's going bonkers with
excessive noise. In any case, the bulge in the AC Adaptor cable near
the 'book connector, which was designed to keep the PB's EMF noise from
getting out, will likewise keep [most of?] that noise from coming in.
So 'Book usage on a isn't close to being an problem unless you use it
for a
couple of days between running the car, or unless you set up a bank of 'em.
Stay well.
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