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Wales
by Joske Vermeule, September 1
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Jun 14th, 2026
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Joined: Sep 2016
Posts: 321
Learner Plates Off!
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OP
Learner Plates Off!
Joined: Sep 2016
Posts: 321 |
Hi,
The ameter on my 1960 Plus 4 doesn't appear to register a charge. It stays resolutely close to 0 but the garage that just sorted out my alternator conversion assures me the battery is charging. Is it time to get thus instrument checked? I'm planning to have all dashboard instrument dials restored to their original appearance in the spring and that would be a good opportunity to do so.
JCK
1960 Plus 4 Roadster
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Joined: Dec 2008
Posts: 22,371 Likes: 354
Roadster Guru Member of the Inner Circle
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Roadster Guru Member of the Inner Circle
Joined: Dec 2008
Posts: 22,371 Likes: 354 |
I recall an issue with ammeters from way back. I believe the ammeter is calibrated to take more charge from an alternator. From memory..... dynamo 30 amps, alternator 60 amps???????
So it may be something to do with instrument calibration?
All this from ageing memory so check it out!!
DaveW
'05 Red Roadster S1
'16 Yellow (Not the only) Narrow AR GDI Plus 4
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Joined: Feb 2012
Posts: 5,659 Likes: 10
Charter Member
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Charter Member
Joined: Feb 2012
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I would check the wiring. The full output from the alternator runs through the ammeter in series. So chunky cable should have be used.
Martin (Deano)
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Joined: Feb 2016
Posts: 8,697 Likes: 416
Needs to Get Out More!
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Needs to Get Out More!
Joined: Feb 2016
Posts: 8,697 Likes: 416 |
I would suspect the garage bypassed the ammeter, possibly due to the new alternator exceeding the ammeter range or maybe by accident if they didn't know what they were doing. Note that a fully charged battery will draw little or no current, but should show some short term charge current after start up, assuming it is still connected.
Either way the alternator could well be charging the battery fine as they have suggested. Quickest way to check is with a voltmeter directly across the battery terminals. It should read 12.7 volts for a fully charged battery when engine not running. After engine start with revs above idle, it should immediately rise above this eventually hitting 14.4 volts give or take.
Centre zero ammeters are very useful instruments but lost favour in the late 60's when the dynamo was replaced by the more powerful, efficient and compact alternator. As these ammeters recorded all current in and out of the battery (other than starter) their electrical location added unreliability and may have contributed to their demise, not to mention cost. A voltmeter is almost as useful, cheaper and much easier to fit.
Richard
2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone
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Joined: Sep 2008
Posts: 516 Likes: 1
Talk Morgan Regular
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Talk Morgan Regular
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Malcolm T
1966 +4
1957 TR3
1963 TR4
1983 LR 110
1985 Robin Hood 2.0l
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Joined: Dec 2011
Posts: 1,943
Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: Dec 2011
Posts: 1,943 |
I would suspect the garage bypassed the ammeter, possibly due to the new alternator exceeding the ammeter range or maybe by accident if they didn't know what they were doing. Note that a fully charged battery will draw little or no current, but should show some short term charge current after start up, assuming it is still connected.
Either way the alternator could well be charging the battery fine as they have suggested. Quickest way to check is with a voltmeter directly across the battery terminals. It should read 12.7 volts for a fully charged battery when engine not running. After engine start with revs above idle, it should immediately rise above this eventually hitting 14.4 volts give or take.
Centre zero ammeters are very useful instruments but lost favour in the late 60's when the dynamo was replaced by the more powerful, efficient and compact alternator. As these ammeters recorded all current in and out of the battery (other than starter) their electrical location added unreliability and may have contributed to their demise, not to mention cost. A voltmeter is almost as useful, cheaper and much easier to fit. I agree. On all 3 of My Morgans I have a voltmeter and that is what I rely on. Not the ammeter which is still in place on 2 of My Morgans. Be careful installing a voltmeter and make sure the ground is solid and adequate.
Button
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Joined: Jan 2009
Posts: 5,945 Likes: 28
Charter Member
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Charter Member
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Hi,
The ameter on my 1960 Plus 4 doesn't appear to register a charge. It stays resolutely close to 0 but the garage that just sorted out my alternator conversion assures me the battery is charging. Is it time to get thus instrument checked? I'm planning to have all dashboard instrument dials restored to their original appearance in the spring and that would be a good opportunity to do so. I would be amazed if you could get an ammeter serviced rather than simply replaced. Bear in mind that starting the engine uses a 1kw motor for maybe 10 seconds so consumes just one quarter of an amp hour from a battery with a cap[acity of say 80 amp hours so the current flow to replace that charge is tiny. The ignition uses very little so unless you have on things like the headlamps or some enormous hi fi set up, there won't be much current flow. Certainly, even with a half empty battery you will never get to the rated output of your alternator,
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Joined: May 2012
Posts: 1,521 Likes: 61
Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: May 2012
Posts: 1,521 Likes: 61 |
I would suspect the garage bypassed the ammeter, possibly due to the new alternator exceeding the ammeter range or maybe by accident if they didn't know what they were doing. Note that a fully charged battery will draw little or no current, but should show some short term charge current after start up, assuming it is still connected.
Either way the alternator could well be charging the battery fine as they have suggested. Quickest way to check is with a voltmeter directly across the battery terminals. It should read 12.7 volts for a fully charged battery when engine not running. After engine start with revs above idle, it should immediately rise above this eventually hitting 14.4 volts give or take.
Centre zero ammeters are very useful instruments but lost favour in the late 60's when the dynamo was replaced by the more powerful, efficient and compact alternator. As these ammeters recorded all current in and out of the battery (other than starter) their electrical location added unreliability and may have contributed to their demise, not to mention cost. A voltmeter is almost as useful, cheaper and much easier to fit. I wanted to fit an ammeter to my 4/4 but opted for a voltmeter instead being an easire job. I am interested in your observation that the voltmeter adds unreliability - I presume its failure could compromise the rest of the electrics - please elaborate.
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Joined: Jun 2015
Posts: 2,095 Likes: 75
Talk Morgan Expert
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Talk Morgan Expert
Joined: Jun 2015
Posts: 2,095 Likes: 75 |
I would suspect the garage bypassed the ammeter, possibly due to the new alternator exceeding the ammeter range or maybe by accident if they didn't know what they were doing. Note that a fully charged battery will draw little or no current, but should show some short term charge current after start up, assuming it is still connected.
Either way the alternator could well be charging the battery fine as they have suggested. Quickest way to check is with a voltmeter directly across the battery terminals. It should read 12.7 volts for a fully charged battery when engine not running. After engine start with revs above idle, it should immediately rise above this eventually hitting 14.4 volts give or take.
Centre zero ammeters are very useful instruments but lost favour in the late 60's when the dynamo was replaced by the more powerful, efficient and compact alternator. As these ammeters recorded all current in and out of the battery (other than starter) their electrical location added unreliability and may have contributed to their demise, not to mention cost. A voltmeter is almost as useful, cheaper and much easier to fit. I wanted to fit an ammeter to my 4/4 but opted for a voltmeter instead being an easire job. I am interested in your observation that the voltmeter adds unreliability - I presume its failure could compromise the rest of the electrics - please elaborate. Suggest another read of what was originally written? It never suggested that a voltmeter would be an issue and i think adequately explains why an ammeter is an increased risk by routing all the current an extra distance via additional wiring and connections.
Doug
2011 Plus 4 in Rich Maroon
1972 750 “ComDom” sprinter
1958 Triton 650
1992 Triumph Trophy 900
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Joined: Feb 2016
Posts: 8,697 Likes: 416
Needs to Get Out More!
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Needs to Get Out More!
Joined: Feb 2016
Posts: 8,697 Likes: 416 |
I would suspect the garage bypassed the ammeter, possibly due to the new alternator exceeding the ammeter range or maybe by accident if they didn't know what they were doing. Note that a fully charged battery will draw little or no current, but should show some short term charge current after start up, assuming it is still connected.
Either way the alternator could well be charging the battery fine as they have suggested. Quickest way to check is with a voltmeter directly across the battery terminals. It should read 12.7 volts for a fully charged battery when engine not running. After engine start with revs above idle, it should immediately rise above this eventually hitting 14.4 volts give or take.
Centre zero ammeters are very useful instruments but lost favour in the late 60's when the dynamo was replaced by the more powerful, efficient and compact alternator. As these ammeters recorded all current in and out of the battery (other than starter) their electrical location added unreliability and may have contributed to their demise, not to mention cost. A voltmeter is almost as useful, cheaper and much easier to fit. I wanted to fit an ammeter to my 4/4 but opted for a voltmeter instead being an easire job. I am interested in your observation that the voltmeter adds unreliability - I presume its failure could compromise the rest of the electrics - please elaborate. Please read my post again Graham, we are in fact in agreement regarding voltmeter.
Richard
2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone
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