On Monday 11 June 2001 14:00, I was honoured by a missive from Jay that said :
> If I remember how those work, the gauge is simply set to hold the needle
> at a certian level when "x" amount of voltage is passed through it
> (14.5V in a 12V system, I think). Even if you reverse the wires, you
> still are not going to pass enough voltage through to deflect it either
> way. You'd have to get a gauge calibrated to 6V, or get yours
> recalibrated. Either that, or test it with a multimeter to make sure it
> actually IS working correctly, and then just remark the face of the
> gauge to show you where it should be at 6V, regardless of the
> "Charge/Discharge" original marking...
There seems to be confusion here, between voltmeter and ammeter.
Both have been used to check the charging/discharging status of a vehicles
electrics, but they work in very different ways, and should not be confused.
The ammeter, used on older vehicles, can be identified by the fact that when
the ignition is turned off, the needle is at rest in the middle of the
scale; it swings right or left from its neutral position to indicate which
way thecurrent is flowing into or out of the battery.
As it relies on the whole of the battery current (except for the starter,
which would overload it) passing through the instrument, it needs a BIG
connection to the battery, which may be a hazard in case of a short, is more
expensive, etc.
It has been replaced in recent times, since vehicles have beenfitted with
alternators and solid-state regulators, by a voltmeter; this can be spotted
by its state when the ignition is turned off: the needle is not at rest in
the middle, but at maximum discharge at the end of the scale.
The main difference between the two, to answer the original query, is that
the ammeter is not voltage-dependent, and the same instrument could be used
as well on a 6 Volt as a 12 Volt vehicle, while the voltmeter-type IS voltage
dependent, and if made for one voltage will not give a reliable indication
under the other voltage.
If connected the wrong way round, the ammeter will show a charge when you
turn the lights on, and a discharge when you turn them off.
If connected the wrong way round, the volmeter will at best show nothing, at
worst burn out ;-(
Cheers,
Ron the Frog, on the banks of the Paraguay River.
--
Support the 28th Amendment:
Convicted felons shall NOT have the right
to demand or expect better treatment or conditions
than the members of the public at large.
--- http://personales.conexion.com.py/~rolgiati ---
This archive was generated by hypermail 2b29 : Thu Jul 05 2001 - 00:40:35 PDT