On 23/6/19 5:47 am, Commander Kinsey wrote:
Modern car alternators seem to be able to give out a huge amount of
current at engine idle speed.* I'm sure my friend got his to give out
pretty much the full 80 amps without revving the engine.* He was
powering a small disco on a campsite :-)

No way to get a full 80 amps out of an alternator *at idle*.


On Sat, 22 Jun 2019 11:00:34 +0100, Brian Gaff
wrote:

Yes indeed, the nominal output of an alternator can be as high as 15
volts,
but even a fully charged car battery is only 13.8v as far as I know and
these days, I'm sure the direction of current flow and voltages are
monitored very well by the computers. In the old days it was a bit of a
black art just relying on the ability of the alternator or dynamo in
the old
bangers.
*Normally the output will change due to engine speed, but* in alternators
there is a voltage regulator inbuilt to keep the* thing pretty
nominal and
of course the thing that then suffers is the charging rate, ie its
going to
be be slower when its not running very fast. I think if a battery dips
below
about 11v outside of starter transients, you have to charge it or get
a new
one. This* very accurate sensing these days can often mask a battery
on its
last legs though, as people tend to ignore* warnings if the car still
works,
then they leave it a couple of days and it won't start!

Brian


--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)