[DeTomaso] Amp gauge

[Kirby Schrader]

Gee, Mike,

I knew how an ammeter worked before you were even born! No need to tell me.
:-)
The GT40 _was_ wired wrong and Superformance sent out a wiring 'fix'.

If you want both, by all means do so!
There has been many a thread on this forum since it started back in
the mid-90's.

Up to you what you use. I used to be a 'dyed in the wool' ammeter fan.
I have converted to voltmeters.

Kirby

On Fri, May 18, 2012 at 12:45 PM,  <MikeLDrew at aol.com> wrote:
>
> In a message dated 5/18/12 9 41 35, kirby.schrader at gmail.com writes:
>
>
>
> I disagree and can not at all see how this approach is valuable...
> That's the way my GT40 came 'incorrectly' wired.
> As you turned things on (fans came on, A/C compressor, etc. etc.),
> the ammeter kept climbing as it measured all the loads. Do you really
> care?
> I suppose for bragging rights. Look at me!!!! 83 amps!!! Woohoo!
>
>
> That's not how an ammeter is designed to work, and as you said, your car was
> wired *incorrectly*.
>
> If the car is shut off and you start adding loads (turning on lights, fans
> etc.) then the ammeter registers in the negative, not positive.  When the
> car is turned on and the alternator is charging, ideally the charge should
> be slightly higher than the load, so that the gauge indicates slightly
> positive.  When you first start the car, if your battery is weak, it will be
> drained quite a bit, so the ammeter will reflect a high state of charge for
> a minute or two as the charging system rapidly returns the battery to a
> fully charged state, and then it will come down to show a slight charge
> (ideally).  If your idle speed is too low, you might show a slight discharge
> at idle with all your components (lights/fans etc.) running.
>
> Sounds like your car had both the supply AND the loads wired on the same
> side of the ammeter?  That would deliver crazy readings for sure.
>
> My point is that it's senseless to take high-load components and wire them
> outside of the ammeter so that the ammeter never registers their draw when
> running.  It's like partitioning your fuel tank so that the fuel gauge only
> registers part of the fuel you have on board.  Doing so guarantees that
> you'd never know exactly how much fuel you have.  What would the point of
> that be?
>
> An ammeter will instantly indicate a charging system failure because the
> needle will displace into the negative side, which is easily apparent.  A
> voltmeter is much more subtle; it will show 12.5 or 13 volts when all is
> good, and will ALSO show 12.5 or 13 volts if your alternator fell out of the
> car, because it's just showing the state of charge of the battery.
>
> The common fallacy is that the voltmeter tells you about your alternator.
> It doesn't tell you JACK about your alternator, it only tells you about the
> state of your battery.  An AMMETER is the only gauge that tells you about
> your alternator, because it instantly informs you as to whether it is
> charging the battery, or if the battery is being discharged.
>
> Over time, if your alternator clatters onto the roadway, your voltmeter will
> drift imperceptibly lower as the battery drains, but at a glance it will
> still look healthy.  When it gets to 11.5 volts or whatever, you'll sputter
> to a stop with a 'dead' battery.
>
> It would be ideal to have both a voltmeter and an ammeter, but given the
> choice I'd take an ammeter any time.
>
> Mike