Hiya .....as I understand it .....its not a "voltmeter" ....its a "charge rate indicator" ....it wont register anything until the alternator is actually charging the battery [ie,when the voltage going into the battery is greater than 12v and the battery is holding its full 12v].
I may be wrong [have been before] ......but I've never had an "A" series car which had a "charge rate indicator" which immediately sprang to life when I switched the ignition on .....in my experience,its always been a case of "wait until the little bit of wire warms up" .
You may find that you'll need to rev the engine somewhat to make the needle move.

hth
Terry

Thanks Terry, that does help!

However, it doesn't explain why it used to register volts as soon as the ignition was turned on, maybe not all the way to the middle, but at least some reading!

Cheers

I was puzzled how you could be specific about voltages in the OP, when iirc there are no digits on the battery meter display. If as Ken says the lower crosshatched section represents 12 - 12.5v, then if the battery's voltage before you start the engine is under 12v then it wouldn't register on the scale, but a healthy battery should have 12.5 - 12.7v at rest.

I think to be sure of what you are dealing with you should double check the voltage with a multimeter, ideally both at the battery and at the battery meter, although the connections for the latter are obviously hard to access.

The power supply for the battery meter is via the ignition switch and a fuse, and if either of these things have a high resistance it will cause a voltage drop, the most likely being a corroded fuse holder.

Lowering the current being drawn through a bad connection will lower the voltage being lost across it, other items drawing power from the same feed are the voltage regulator and the oil pressure light, if temporarily disconnecting one or both of these causes a rise in the battery meter display then it supports the bad connection theory.

Thanks Joolz, that makes sense to me.

Let's say the battery isn't producing enough volts to register a reading at rest, surely it will eventually be charged by the car back up to it's capacity (for want of a better word) - unless by battery is duff, which is possible i guess.

If the battery is duff, and it's rest voltage is under 12v, I expect you would notice when you start the car. If the starter spins over at a reasonable rate then there's not a lot wrong with the battery.

The system voltage should be around 14.4v with the engine running, when the engine is stopped the battery voltage should slowly drop to 12.5v over a minute or so, the rate at which it drops will be exponential, initially dropping quite quickly but slowing down as it nears it's rest voltage. If the engine has been running a while it should have charged the battery enough for it to hold 12.5v, if the battery drops below that it either needs more charging or it's duff.

I'm still inclined to be sceptical about the battery meter reading, Check the voltage directly at the battery and if that gives you 12.5v at rest and 14 -14.5v when revved, then the charging system is all good.

Also note, the reference voltage being supplied to the voltage regulator is the same one being displayed on the battery meter, as they are both fed from the same fuse. If this voltage is low the regulator will be telling the alternator to over charge to compensate. It would be worth making sure the fuse contacts are clean to prevent this.

yes they all do that its less of a "meter" more an "Indicator"

i think you may have a case of automotive hypochondria

Just because Citroen dumbed things down for their owners' handbook by referring to this instrument as a 'battery meter' or a 'battery charge indicator' doesn't change the fact that it is actually a voltmeter, does it?

At least one owner I met a long time had convinced himself that it was a temperature gauge, since the harder he trashed his Dyane, the higher was the reading on the instrument...

Here's some detailed information on battery voltage vs time of resting.
http://www.pbase.com/mainecruising/batt ... _of_charge

ken

Well that's good enough for me! BUT, it still doesn't explain why it used to give me a reading when the ignition was turned on.

It used to be broken, now it isn't. I don't have a gauge on my Special, but the Charleston I occasionally drive doesn't seem to register anything until the engine is running.

If you turn on the ignition you need to wait for at least half a minit before the gauge starts to fire up*, if you wait that long suddenly the pointer comes in action and if you don't start the engine it will go up only a few mm and staying in the left red zone which indicates that the alternator isn't loading, which seems to be spot on when your engine doesn't run..... when you run the engine it needs to stay around the middle of the gauge.

p.s. if you run on points disconnect your coil otherwise it can damage (heating up) when you leave ignition on without running the engine.....

* the gauge needs to heat up before it starts to work.....