Home » Public Forums » GMCnet » Weird Gauge Readings (Was: Trip Report Too)
| Weird Gauge Readings [message #216036] |
Sun, 28 July 2013 21:24  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Further observation of my volt and amp gauge readings seems to say that the amperage is closer to 45 - 55 while the 3-way fridge and lights are on. I don't know how accurate these gauges are, so I'm not sure of the readings. The volt meter reads 13+ volts...with the lights off. When I turned on the running lights, it immediately jumps down to just above 12 volts. When the headlights go on, it jumps down a little more.
Still, the batteries are fully charged and there seems to be no real problem with the charging system. Evidently, the gauges are just hooked up to read a little bit strangely. It is really of minor concern to me, since the system is working properly, but I'd still like to know why the gauges read this way. It would be helpful to have them giving me accurate readings in the event that I have to try to diagnose a real problem whenever one comes up.
Any ideas?
Thanks,
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Weird Gauge Readings [message #216044 is a reply to message #216036] |
Sun, 28 July 2013 22:10  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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| Carl S. wrote on Sun, 28 July 2013 21:24 |
Further observation of my volt and amp gauge readings seems to say that the amperage is closer to 45 - 55 while the 3-way fridge and lights are on. I don't know how accurate these gauges are, so I'm not sure of the readings. The volt meter reads 13+ volts...with the lights off. When I turned on the running lights, it immediately jumps down to just above 12 volts. When the headlights go on, it jumps down a little more.
Still, the batteries are fully charged and there seems to be no real problem with the charging system. Evidently, the gauges are just hooked up to read a little bit strangely. It is really of minor concern to me, since the system is working properly, but I'd still like to know why the gauges read this way. It would be helpful to have them giving me accurate readings in the event that I have to try to diagnose a real problem whenever one comes up.
Any ideas?
Thanks,
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Just because you can't hear it, doesn't mean your alternator belt is not slipping.
If your headlights dim and brighten with the turn signal flashers, you need a new alternator belt.
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| Re: Weird Gauge Readings [message #216046 is a reply to message #216044] |
Sun, 28 July 2013 22:18 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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| A Hamilto wrote on Sun, 28 July 2013 20:10 |
| Carl S. wrote on Sun, 28 July 2013 21:24 |
Further observation of my volt and amp gauge readings seems to say that the amperage is closer to 45 - 55 while the 3-way fridge and lights are on. I don't know how accurate these gauges are, so I'm not sure of the readings. The volt meter reads 13+ volts...with the lights off. When I turned on the running lights, it immediately jumps down to just above 12 volts. When the headlights go on, it jumps down a little more.
Still, the batteries are fully charged and there seems to be no real problem with the charging system. Evidently, the gauges are just hooked up to read a little bit strangely. It is really of minor concern to me, since the system is working properly, but I'd still like to know why the gauges read this way. It would be helpful to have them giving me accurate readings in the event that I have to try to diagnose a real problem whenever one comes up.
Any ideas?
Thanks,
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Just because you can't hear it, doesn't mean your alternator belt is not slipping.
If your headlights dim and brighten with the turn signal flashers, you need a new alternator belt.
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Thanks, A, but that's not it. No dimming of headlights or any other accessory. I have a double pulley on the alternator and it does NOT slip. Plenty of amps coming from the alternator. I am not good at electrical things, but I'm pretty sure that if the belts were slipping, and that was the cause of the low voltage reading, the ammeter would read low too instead of going up when the lights are turned on.
Good thought though.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Weird Gauge Readings [message #216062 is a reply to message #216036] |
Mon, 29 July 2013 00:16 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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The wire circuit the volt meter is connected too most likely has a voltage drop in it.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Weird Gauge Readings [message #216078 is a reply to message #216036] |
Mon, 29 July 2013 08:10 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| Carl S. wrote on Sun, 28 July 2013 22:24 |
Further observation of my volt and amp gauge readings seems to say that the amperage is closer to 45 - 55 while the 3-way fridge and lights are on. I don't know how accurate these gauges are, so I'm not sure of the readings. The volt meter reads 13+ volts...with the lights off. When I turned on the running lights, it immediately jumps down to just above 12 volts. When the headlights go on, it jumps down a little more.
Still, the batteries are fully charged and there seems to be no real problem with the charging system. Evidently, the gauges are just hooked up to read a little bit strangely. It is really of minor concern to me, since the system is working properly, but I'd still like to know why the gauges read this way. It would be helpful to have them giving me accurate readings in the event that I have to try to diagnose a real problem whenever one comes up.
Any ideas?
Thanks,
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Carl,
While there is some minor information missing, nothing here is that far out of line. If this "gauge" is an automotive type, then expecting any accuracy is kind of foolish. Most I have seen have a needle that is 1/3~1/2 a volt wide.
I am going to make the rash assumption that the 13+ is either with the engine running or on shore power, but you didn't say, and in those cases, this is normal. Where you are seeing the 45~55 amps go is anybody's guess. (Remember the needle width thing.)
The changes you are seeing would be expected if given the instrument connections are probably where they would be most convenient.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Weird Gauge Readings [message #216106 is a reply to message #216078] |
Mon, 29 July 2013 11:50 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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| Matt Colie wrote on Mon, 29 July 2013 06:10 |
| Carl S. wrote on Sun, 28 July 2013 22:24 |
Further observation of my volt and amp gauge readings seems to say that the amperage is closer to 45 - 55 while the 3-way fridge and lights are on. I don't know how accurate these gauges are, so I'm not sure of the readings. The volt meter reads 13+ volts...with the lights off. When I turned on the running lights, it immediately jumps down to just above 12 volts. When the headlights go on, it jumps down a little more.
Still, the batteries are fully charged and there seems to be no real problem with the charging system. Evidently, the gauges are just hooked up to read a little bit strangely. It is really of minor concern to me, since the system is working properly, but I'd still like to know why the gauges read this way. It would be helpful to have them giving me accurate readings in the event that I have to try to diagnose a real problem whenever one comes up.
Any ideas?
Thanks,
|
Carl,
While there is some minor information missing, nothing here is that far out of line. If this "gauge" is an automotive type, then expecting any accuracy is kind of foolish. Most I have seen have a needle that is 1/3~1/2 a volt wide.
I am going to make the rash assumption that the 13+ is either with the engine running or on shore power, but you didn't say, and in those cases, this is normal. Where you are seeing the 45~55 amps go is anybody's guess. (Remember the needle width thing.)
The changes you are seeing would be expected if given the instrument connections are probably where they would be most convenient.
Matt
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Thanks Matt,
All readings were with the engine running while driving down the interstate at 62 mph. I'm sure the gauges are not accurate and merely provide a suggestion of what is going on. In discussing this with my mechanic friend this morning, he told me he was getting the same kinds of readings from the volt (battery) gauge on his SOB. He freaked out, convinced himself that the alternator was not putting out, bought a new alternator and replaced it, only to have the same readings a few miles down the road.
I guess you're right and there is nothing out of line. It's just confusing to see 40 - 50 amps on one (inaccurate) gauge and 12 volts (or less) on the other. Still, all batteries are receiving a full charge and the strange readings only occur when the lights are on along with the dash air and the fridge.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Weird Gauge Readings [message #216216 is a reply to message #216106] |
Mon, 29 July 2013 23:41 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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To expand a little on Matt's comments. Where you are reading the voltage from makes a lot of difference. The are voltage drops all over that coach. The biggest one besides the isolator in the fusible link. I suggest that you watch the voltage at the out put of the isolator or across the battery. The problem with those two locations is how to turn off the meter when the coach is being used.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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