Hi Stu, Dave,

>would have though it is mutch like an Ameter so a wire wound coil around a magnet attached to the pointer

Yes and no:-

. Voltmeter is connected between +ve and -ve so it's an electrical resistance, "check with a meter that there is continuity between the terminals" is "check with an Ohm-meter or multi-meter set to Ohms", that should show - correctly - there is measurable resistance (Ohms).

. Otoh, Ammeter is never an electrical resistance, because it's never (correctly) connected between +ve and -ve, "check with a meter that there is continuity between the terminals" should show there is (virtually) no resistance.

>"battery condition" gauge. I think it must read voltage.

As connecting specifically an Ammeter between +ve and -ve will "let the smoke out", as well as checking with a meter, are there any indications on the gauge:-

. numbers between, say, 10 and 16 probably indicate a Voltmeter, higher numbers probably indicate an Ammeter (unless Citroen fitted Lucas motorcycle alternators to 2CV?);

. multi-coloured scale, red at the top likely indicates a Voltmeter (high Volts likely warning of a regulation failure, as well as being bad for bulbs); otoh red at the bottom likely indicates an Ammeter (low Amps being bad for electrics longevity)?

Otoh, connecting a Voltmeter in line between one battery terminal and the rest of the van's electrics will cause the van's electrics either to function badly (dim bulbs) or not at all, because a Voltmeter is an electrical resistance and, so connected, is 'in series' with all the other resistances (ignition coil, bulbs, etc.).

Hth?

Regards,