XPost: uk.rec.driving, alt.home.repair, uk.d-i-y
From: xenolith@optusnet.com.au
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)
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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