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Re: Voltmètre or Ampmeter? [Re: Toucan] #610374
31/12/19 09:02 AM
31/12/19 09:02 AM
Joined: Feb 2016
Posts: 3,547
East Harling, Norfolk UK
RichardV6 Offline
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RichardV6  Offline
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Joined: Feb 2016
Posts: 3,547
East Harling, Norfolk UK
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.


Richard

2018 Roadster - Red/Magnolia - "Morton"
1966 Land Rover series 2a SWB
1960 Velocette Venom
Re: Voltmètre or Ampmeter? [Re: Toucan] #610387
31/12/19 11:08 AM
31/12/19 11:08 AM
Joined: Jul 2015
Posts: 921
Shropshire
MDS61 Offline
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MDS61  Offline
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Joined: Jul 2015
Posts: 921
Shropshire
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?"


Honesty means doing it right, even when no one is looking!

2004 Roadster S1 3.0 V6 - "Seve"

Mark
Re: Voltmètre or Ampmeter? [Re: John V6] #610389
31/12/19 11:17 AM
31/12/19 11:17 AM
Joined: Dec 2019
Posts: 32
Touraine, France
Toucan Offline OP
Just Getting Started
Toucan  Offline OP
Just Getting Started

Joined: Dec 2019
Posts: 32
Touraine, France
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.


Toucan 1981 4/4 Kent
Re: Voltmètre or Ampmeter? [Re: Toucan] #610391
31/12/19 11:26 AM
31/12/19 11:26 AM
Joined: Dec 2009
Posts: 26,732
Devonshire
+8Rich Offline
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+8Rich  Offline
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Joined: Dec 2009
Posts: 26,732
Devonshire
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.


Regards Richard

1999 Indigo Blue +8
2009 4/4 Sport Green prev
1994 Connaught Green +8 prev





Re: Voltmètre or Ampmeter? [Re: Toucan] #610410
31/12/19 12:38 PM
31/12/19 12:38 PM
Joined: Jul 2007
Posts: 19,159
Suffolk
John V6 Offline
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John V6  Offline
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Joined: Jul 2007
Posts: 19,159
Suffolk
Originally Posted by Toucan
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.

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


JohnV6
2006 Indigo Blue Roadster S1
2014 Brooklands Edition Roadster "Brookland's Belle" #5 of 50
Re: Voltmètre or Ampmeter? [Re: Toucan] #610416
31/12/19 01:14 PM
31/12/19 01:14 PM
Joined: Oct 2019
Posts: 1,635
Aberdeenshire
Image Offline
Talk Morgan Enthusiast
Image  Offline
Talk Morgan Enthusiast

Joined: Oct 2019
Posts: 1,635
Aberdeenshire
I guess it took Morgan longer to use up their stock of wiring diagrams than it did their box of ammeters!! :-)

K

Re: Voltmètre or Ampmeter? [Re: Image] #610438
31/12/19 02:26 PM
31/12/19 02:26 PM
Joined: Dec 2019
Posts: 32
Touraine, France
Toucan Offline OP
Just Getting Started
Toucan  Offline OP
Just Getting Started

Joined: Dec 2019
Posts: 32
Touraine, France
rofl


Toucan 1981 4/4 Kent
Re: Voltmètre or Ampmeter? [Re: MDS61] #610524
31/12/19 09:33 PM
31/12/19 09:33 PM
Joined: Dec 2011
Posts: 1,943
Seattle, USA
B
Button Offline
Talk Morgan Enthusiast
Button  Offline
Talk Morgan Enthusiast
B

Joined: Dec 2011
Posts: 1,943
Seattle, USA
Originally Posted by MDS61
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?"


+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!!!!!!


Button
Re: Voltmètre or Ampmeter? [Re: Button] #610726
02/01/20 08:15 AM
02/01/20 08:15 AM
Joined: Feb 2016
Posts: 3,547
East Harling, Norfolk UK
RichardV6 Offline
Talk Morgan Addict
RichardV6  Offline
Talk Morgan Addict

Joined: Feb 2016
Posts: 3,547
East Harling, Norfolk UK
Originally Posted by Button
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.

Last edited by Richard Wood; 02/01/20 08:16 AM.

Richard

2018 Roadster - Red/Magnolia - "Morton"
1966 Land Rover series 2a SWB
1960 Velocette Venom
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