Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Voltmètre or Ampmeter?

As already mentioned ammeters, which measure the current both going into and out of the battery (hence centre zero scale) generally went out of use when higher current alternators took over around the late 1960's. If you know what to look for they offer more immediate information on your cars electrical performance than a voltmeter. Downside is that all the battery current has to pass through the instrument or its shunt which is usually integral to it. This is an extra link in the chain involving higher current handling cables so generally not practical with modern car alternators putting out 50 + amps for reasons of reliability and cost. Higher current ammeters with remote shunts are available, the ones on my boat measuring up to 500 amps, but not practical for use on cars.

A voltmeter on the other hand is very easily fitted without interrupting any of the existing car electrics, allowing an approximate guide to battery state of charge before engine started and also if it is being charged to some degree afterwards.

I love instruments within the car to tell me "stuff".

However, as soon as one of these does something - out of the ordinary, I can go into a blind panic!

The missus modern however, does not even have a temp gauge, yet I never worry about the car over-heating....."knowing stuff - is important - but can worry you?"

JohnV6, l didn't find the one with Voltmeter,alll found were with Ammeter, including the one within the instructions booklet provided with the car and hopefully gone to me. Could you provide a link or send me the right one via MP?

BTW, thanks all of you who answered, it helps. I didn't know the link between Ammeter and dynamos / Voltmeter and alternator.
Seems that factory improvement was not synchronized with documentation update.

If you click on the Blue Voltmeter link on my earlier reply you will see the link to the diagram from gomog they call it a volt gauge , Lorne is the owner of that very useful site. The diagram is for an 1988 model but the first one with a voltmeter I could find.

GoMog has an 84 car
http://www.gomog.com/allmorgan/Wiring44Diagram1984.jpg
and a 74 car
http://www.gomog.com/allmorgan/wiring44diagram1973.jpg

Both as you say show ammeters

I guess it took Morgan longer to use up their stock of wiring diagrams than it did their box of ammeters!! :-)

K

+1 - My '63 +4 has a ammeter as well as a voltmeter. Not sure what the ammeter does except scare the hell out of Me. As I have an Alternator I pay attention to the Voltmeter and not the ammeter. My Son In Law (auto electric mechanic) says the ammeter is "TROUBLE". Remove it!!!!!!

Having both gives you the fullest picture on battery charging and electrical consumption but OTT on a car. Basically ammeter gives instantaneous info whilst voltmeter gives trend (cause and effect). Your SIL is right though in suggesting you remove ammeter unless it's kept for originality. The shunt within is necessarily a very low resistance so mechanically robust, but the extra cabling and connection's on what is the main power feed to all but starter add a degree of unecessary unreliability.