Use a voltmeter to check system voltage i.e. on a brown at the fuse box to
ground. All switched off should read about 12.8v on a good battery. When
started and revved to at least 1200rpm you should read about 14v. Switch on
all the electrical load you can and it should still read in excess of 13v.
A battery can have internal defects that cause it not to hold a charge and
giving it a quick charge can allow it to start the car, only for it to go
flat again the next time you switch off. Unlikely with a new battery.
You could also have a drain on the battery that is discharging it while
parked. Remove the battery ground strap and connect a test lamp in its
place. With everything switched off (including doors and boot.trunk closed)
you should have no glow. Any glow indicates a drain. If you get no glow
connect a volt-meter on its 12v scale in place of the test lamp. If it
reads 12v you have a small drain, if it reads less than 12v you have a very
small drain which could be electric clock or radio, or even dampness on top
of the battery.
If you have any drain at all disconnect the alt plug first, if it goes then
the diode pack in the alt is faulty which could be affecting charge as well
as draining the battery. If pulling the alt pug doesn't clear the drain
pull the bottom fuse in the 2-way or 4-way fuse block (brown to purple) then
in-line fuses in browns like for hazards, then browns off things like
ignition, light switch, relays etc to track it down. If none of those
clears it remove the browns from the solenoid or stud under the RHS
toe-board.
PaulH.
----- Original Message -----
From: Rick Sinclair <RHSinclair@USWest.net>
To: MG list <mgs@autox.team.net>
Sent: Monday, June 12, 2000 11:25 PM
Subject: Alternator testing.
> Hi all,
> My '68 'B is having a problem with the charging system. We took it
> out for a drive, tried to start it up later, and get the
> solenoid buzzing noise. Put the charger on it, waited for a while,
> tried it again, and it starts right up. Question:
>
> 1) How do you test the alternator? Don't really want to take it to
> Napa until I test it here first. There was a How-to in the last Moss
> catalogue, but I can't find mine.
>
> 2) Could this be a battery? I just bought a new one a couple months
> ago,
> so I don't think it's the problem.
>
> Anyway, It's a little hard to work on him right now (I've decided to
> call him RC), because my Mom received an entire pickup truck load of
> sheep's wool, and decided the best place to put it was IN AND ON my
> car!! ARRRGHHHH.
>
> Thanks in advance.
>
> Rory
> '68 'B (RC)
>
>
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