The ammeter and voltmeter tell you exactly the same thing - is the battery
being charged or not - in different ways. For an ammeter to show a charge
the system voltage must be above the nominal battery voltage i.e. c14v as
opposed to 12.8v. If the voltmeter is showing c14v then the battery is
being charged. A voltmeter has a far bigger range of needle movement that
an ammeter for the faults likely to be encountered, but an ignition warning
light coming on is far easier to spot then either of them. A correctly
working ignition warning light (it is not known as 'the idiot light' -
'only an idiot ignores the fact that it is not working' for nothing) shows
pretty much the same thing. None of them tell you if your battery will have
enough capacity in it to start next morning. The attached-shunt ammeter
introduces several additional points of failure plus needs wiring in really
heavy gauge, and introduces even more volt-drop into the system. The
remote-shunt ammeter is better (only thin wires up from solenoid to gauge)
but the voltmeter is simpler still. I've fitted both in the past just 'cos
they looked good. But then I also fitted audible warnings to my oil and
ignition warning lights. I can't say any of them have told me much useful
in 30 years of driving, not even when the V8 blew a hose, pumped out all its
water and the oil and temp gauges still showed 'normal', it was only a
suspicion about a misfire under load that caused me to pull over and only
then see the steam. However the tach and warning light told me where to
look when the engine just cut one day. Even the factory oil and temp gauges
are more worry than use, judging by the number of 'is my temp too
high/pressure too low' questions we get on this list and the BBS. Even the
factory only discovered that the V8 engine hot idled at 8psi when they put
it in the MGB.
Fit one/both if you like, but lets be honest about the relative merits and
pitfalls.
PaulH.
----- Original Message -----
From: Dave Wood <djw69@idt.net>
To: mgs <mgs@autox.team.net>
Sent: Thursday, October 19, 2000 4:22 PM
Subject: Re: adding an ammeter to a RBB
> Hans,
>
> I know I should just keep my mouth shut, but I have to disagree with your
> evaluation of the worth of a voltmeter. The voltmeter will show 13.5 or
14
> volts constantly as long as your alternator or generator/regulator is
> working properly. It does not tell you anything about the charging status
> of your battery. At least the idiot light lets you know if the alternator
> is not keeping up with the required current. The ammeter on the other
hand
> tells you that the battery is charging or discharging and how much. When
> you get used to watching it you can tell when it's time to clean the
> terminals or replace the battery by the length of time it takes for the
> ammeter to drop towards zero after you start you car. Granted, when a
> voltmeter suddenly changes from the normal reading, you probably have a
> problem with the alternator, but you should be aware of that already if
you
> drive at night and see your lights get dim or too bright. As far as the
> comment (not by you) that you are just introducing more possible points of
> failure, I would suggest that you have a professional install the
instrument
> if you don't know how to make a lasting connection. (I have my asbestos
> underwear on so go for it guys!).
>
> Dave 72 B
>
> ----- Original Message -----
> From: <Duinhoven_Hans@emc.com>
> To: <ccrobins@ktc.com>; <schooler@erols.com>
> Cc: <macy@bblmail.psycha.upenn.edu>; <djw69@idt.net>; <mgs@autox.team.net>
> Sent: Wednesday, October 18, 2000 11:58 PM
> Subject: RE: adding an ammeter to a RBB
>
>
> All,
>
> A few months ago I raised the same topic for my brother. He has an ammeter
> in his Midget, but not connected.
> All advises were: don't hook it up.
> A Voltmeter is indicating the same: is my battery loaded yes or no.
>
> Cheers,
>
> Hans
>
> -----Original Message-----
> From: Charley & Peggy Robinson [mailto:ccrobins@ktc.com]
> Sent: donderdag 19 oktober 2000 4:35
> To: Bill Schooler
> Cc: Larry Macy; Dave Wood; mgs
> Subject: Re: adding an ammeter to a RBB
>
>
> Hi bill,
>
> That is exactly what I thought. KISS, eh?
>
> Cheers,
>
> CR
>
>
>
> Bill Schooler wrote:
> >
> > ...as John Twist has said (in relation to installing an ammeter), "Why
> would you
> > want to introduce more points for potential failure in an MG's wiring
> system?"
> >
> > Bill
> >
> >
>
>
>
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