Home » Public Forums » GMCnet » [GMCnet] The Importance of a Voltmeter
| [GMCnet] The Importance of a Voltmeter [message #368225] |
Thu, 30 December 2021 12:45  |
GMCWiperMan
Messages: 1248
Registered: December 2007
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I just stumbled across this note from 2006; it's still applicable, so I'm
posting it for everyone's consideration:
Voltmeter to the Rescue
Do you have a voltmeter monitoring your chassis battery voltage? You
should. Here’s an example of why: We returned from Florida last night
after a three week, two rally, two GMC alternator excursion. As we left
Melbourne, FL enroute to Bowling Green, FL, Elaine and I both smelled
something funny, so I stopped and tried unsuccessfully to find the
source. When I restarted the engine, I noticed that my dash voltmeter was
reading 16 VDC and sometimes jumping even higher. Knowing that much
voltage would damage the batteries, we turned on the headlights, A/C
blower, and every interior light we could find. That dropped the voltmeter
reading to about 15 VDC, a marginally high voltage, but not terribly
destructive, so we continued the trip. After about 15 minutes, the
voltmeter reading dropped quickly to 12.5 VDC, which indicated that we were
operating on the chassis battery alone, with no alternator contribution.
With only 130 miles to travel, I decided to continue. Over the next 100
miles, the voltmeter dropped steadily; at 10 VDC, the engine faltered so I
switched on the house batteries using my non-momentary battery boost
switch. The voltage quickly climbed back to 12.5 VDC, the engine ran fine,
and we reached Bowling Green with no further difficulty.
The next day, after failing to repair the dead alternator, I bought a
rebuilt one and installed it. The voltmeter once again read 14.7 VDC, the
exact voltage indicated on Advance Auto’s tester. I kept the old
alternator so I can repair it for a spare and we continued our travels
around Florida. About 100 miles before we got home, the voltmeter again
jumped to over 16 VDC and the inverter I use to run my laptop computer
kicked off because of the overvoltage condition. Even turning on all the
lights would not bring the voltage back down and it would occasionally jump
even higher, so I decided on a temporary repair. Reasoning that the
just-replaced alternator was probably OK, the most likely reason for the
voltage going high was that the voltage sense lead was not providing the
battery voltage to the alternator, causing it to “think” it needed to
produce more voltage. A jumper wire from the #2 lead on the alternator to
the chassis battery corrected the problem and allowed us to continue to
Americus without further difficulty.
The voltmeter alerted me to the original alternator problem so I could take
preventive action (by placing additional load on the alternator) before it
damaged my batteries. Then when the second alternator began to act up, it
enabled me to determine the probable cause of the problem and provide a
temporary fix without damaging the batteries or the rebuilt alternator.
Neither of those problems would have been indicated by the GEN light until
the alternators actually failed. A voltmeter is money well spent.
Ken H.
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| Re: [GMCnet] The Importance of a Voltmeter [message #368233 is a reply to message #368225] |
Thu, 30 December 2021 14:23  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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I talk to a gmc owner of some sort every month that has no clue how to test voltage on anything. Some have had same dead battery problems they cant solve and still have not bought a volt meter to do troubleshooting with.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| [GMCnet] Re: The Importance of a Voltmeter [message #368236 is a reply to message #368225] |
Thu, 30 December 2021 14:23 |
CJV
Messages: 49
Registered: December 2021
Karma: 1
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I've printed this off and saved it my GMC data file.....thank you....
CJ Vermeulen, Scribbler
----- Original Message -----
From: "Ken Henderson"
To: "gmclist"
Sent: Thursday, December 30, 2021 12:45:04 PM
Subject: [GMCnet] The Importance of a Voltmeter
I just stumbled across this note from 2006; it's still applicable, so I'm
posting it for everyone's consideration:
Voltmeter to the Rescue
Do you have a voltmeter monitoring your chassis battery voltage? You
should. Here’s an example of why: We returned from Florida last night
after a three week, two rally, two GMC alternator excursion. As we left
Melbourne, FL enroute to Bowling Green, FL, Elaine and I both smelled
something funny, so I stopped and tried unsuccessfully to find the
source. When I restarted the engine, I noticed that my dash voltmeter was
reading 16 VDC and sometimes jumping even higher. Knowing that much
voltage would damage the batteries, we turned on the headlights, A/C
blower, and every interior light we could find. That dropped the voltmeter
reading to about 15 VDC, a marginally high voltage, but not terribly
destructive, so we continued the trip. After about 15 minutes, the
voltmeter reading dropped quickly to 12.5 VDC, which indicated that we were
operating on the chassis battery alone, with no alternator contribution.
With only 130 miles to travel, I decided to continue. Over the next 100
miles, the voltmeter dropped steadily; at 10 VDC, the engine faltered so I
switched on the house batteries using my non-momentary battery boost
switch. The voltage quickly climbed back to 12.5 VDC, the engine ran fine,
and we reached Bowling Green with no further difficulty.
The next day, after failing to repair the dead alternator, I bought a
rebuilt one and installed it. The voltmeter once again read 14.7 VDC, the
exact voltage indicated on Advance Auto’s tester. I kept the old
alternator so I can repair it for a spare and we continued our travels
around Florida. About 100 miles before we got home, the voltmeter again
jumped to over 16 VDC and the inverter I use to run my laptop computer
kicked off because of the overvoltage condition. Even turning on all the
lights would not bring the voltage back down and it would occasionally jump
even higher, so I decided on a temporary repair. Reasoning that the
just-replaced alternator was probably OK, the most likely reason for the
voltage going high was that the voltage sense lead was not providing the
battery voltage to the alternator, causing it to “think” it needed to
produce more voltage. A jumper wire from the #2 lead on the alternator to
the chassis battery corrected the problem and allowed us to continue to
Americus without further difficulty.
The voltmeter alerted me to the original alternator problem so I could take
preventive action (by placing additional load on the alternator) before it
damaged my batteries. Then when the second alternator began to act up, it
enabled me to determine the probable cause of the problem and provide a
temporary fix without damaging the batteries or the rebuilt alternator.
Neither of those problems would have been indicated by the GEN light until
the alternators actually failed. A voltmeter is money well spent.
Ken H.
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| [GMCnet] Re: The Importance of a Voltmeter [message #368243 is a reply to message #368237] |
Thu, 30 December 2021 16:08 |
dsmithy
Messages: 210
Registered: July 2012
Location: Lincoln Nebraska
Karma: 0
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Last summer I bought one even cheaper than the one like John P. posted and didn’t trust it as the voltage slowly settled to 10V while we were plugged in and on the Progressive charger. By the time I woke up and tested the brand new chassis battery with my good meter it was below 10V. Turns out my combiner had decided to go on vacation and disconnecting it forced it to reset so everything returned to normal. Of course, now I have to live with whatever damage the deep discharge caused. I ordered a couple of adapter/meters like John referenced and this time I’ll compare their readings with my good meter and trust them.
There are many that go down the road with no more than a credit card, but I hope they also have a good meter stashed somewhere. It’s a source of nuanced diagnostic information that just can’t be gathered any other way.
> On Dec 30, 2021, at 2:43 PM, John Phillips wrote:
>
> For those who just want to charge a phone or two and get a battery voltage
> indication, I think this is a good first step.
> https://www.amazon.com/Palumma-Charger-Adapter-Display-Battery/dp/B0773BYS6P/ref=asc_df_B0773BYS6P/?tag=hyprod-20&linkCode=df0&hvadid=30982116 3350&hvpos=&hvnetw=g&hvrand=4181744818749251922&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=90 32425&hvtargid=pla-571877554217&psc=1&tag=&ref=&adgrpid=57207177050&hvpone=&hvptwo=&hvadid=309821163350&hvpos=& ;hvnetw=g&hvrand=4181744818749251922&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032425&hvtargid=pla-571877554217
>
> On Thu, Dec 30, 2021 at 12:24 PM Jon Roche wrote:
>
>> I talk to a gmc owner of some sort every month that has no clue how to
>> test voltage on anything. Some have had same dead battery problems they
>> cant solve and still have not bought a volt meter to do troubleshooting
>> with.
>>
>>
>> --
>> Jon Roche
>> 75 palm beach
>> EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
>> St. Cloud, MN
>> http://lqqkatjon.blogspot.com/
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
>
>
> --
>
> *John Phillips*
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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Douglas & Virginia Smith,
dsmithy18 at gmail,
Lincoln Nebraska,
’73 “Sequoia” since ‘95: "Wanabizo";
Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy wheels/Sundry other
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| Re: [GMCnet] The Importance of a Voltmeter [message #368245 is a reply to message #368225] |
Thu, 30 December 2021 16:59 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Ken,
I had never placed a lot of value in a system voltmeter, but while on the home bound leg of the excursion to an international the silly little read-out in the USB multi-charger we had in the cab started showing numbers lower than expected. I knew the alternator couldn't be real bad as I had had it open to clean it several months before. But I switched in the house bank and was not worried as we have a separate generator battery. We had another stop scheduled to make and internet said that there was a Delco Warehouse a block down from the planned stop. So, I got there and wandered in and asked the counter person if they might have a regulator for this old beast. The counter person said that there was no chance that they would have any thing that old, but four blocks west and two blocks south was a shop that would.
Off we went and we got there with not a long time before the closing on the sign. The guy that ran the place came out to look and said he was sure to have what it needed, but it was too hot for him to take it out. I said I would get it out and bring it in a couple of minutes. (Remember, I was a steam engineer for a long time and hot is just not an issue.) I pulled it out and walked in while he was finishing a discussion with a pair he said were from Columbia. Then he looked at me and grabbed the alternator and said "Wow, it is still hot. These 27SI are hard to kill, but let's what it is not doing." I told him no need, the regulator was gone. He nodded put it down on a bench and took it down like any of us might break down an 1911. As if he were a musician, he went over the internals with a VOM and just kept nodding. He popped out the regulator looked at it and said "Oh, remote excitation" and hooked it to a tester right there on the bench pushed a button and a needle didn't go up scale very far. He humpfed something like "It's bad, but let's do this some favors while we have it open." He turned around and put the rotor in a little lathe and cleaned up the slip rings, got a new regulator out of the drawer under the bench and new pair of brushes. He reassembled it with the same confidence that he shown when he broke it down. I have forgotten what he asked for this service, but it was silly and I was not going to argue. He went to the phone and as near as I could tell told someone he would be home as some as his customer was good.
I had just finished tightening the belt when my guy showed up that the door. The engine started right away as usual and the little display popped to 13.6. With that I said another round of thank yous and go have dinner.
When we got down the road and I realized that the main engine battery was not going to come up to 14.2, I figure out that he had put in a standard regulator, not remote sensing. They are a different part number. We would finish the excursion with a very undesirable one wire alternator. But hey, this got us home and then I got the right number to put in there.
That alternator might be installed still, but in the accident in 2019 something happened and the sheave got loose and damaged the shaft. I have the parts to repair that, but it is not high on the list as I had a spare on the shelf.
We now have a Digi-panel that does have a system voltage display. The Digipanel is how I knew we were loosing that alternator on the on the way home, but we were close enough that it was not a worry.
I do carry some test gear in the coach. The most used is a "magic screwdriver". I made this by selecting a rubber grip screwdriver out of a cheap tools bin somewhere and sliding the rubber grip off the plastic handle so I could hollow that to fit an instrument light bulb. Then I crammed in a piece a of wire next to the bulb base that had an alligator clip its end. When you get it right, the plastic handle lights up. This tool has been a traveling companion for at least 50 years. I also carry Fluke 77, this one is newer than my original. My original 77 is from the first lot to come into Detroit and that one is over 40yo. (I know because I bought it before my daughter was born.) But that one took some damage a while ago and I don't want it to travel any more, so it lives on a bench at home. That newer 77 may get retired soon and I have an Amazon cheapy that has an inductive DC current sense. I don't rust it yet.
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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| [GMCnet] Re: The Importance of a Voltmeter [message #368262 is a reply to message #368260] |
Fri, 31 December 2021 16:57 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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My fluke is on it's second battery. I have had it since at least 1992 or
so. A customer, who was a HVAC guy was dying from cancer and gifted me the
meter. He is long gone now, but his fluke 77 lives on. Probably will
outlast me too. Best tool in my box.
Jim Hupy
Salem, Oregon
On Fri, Dec 31, 2021, 2:51 PM Matt Colie wrote:
> JohnL455 wrote on Fri, 31 December 2021 17:16
>> Fluke, a tool you don’t have to fix before you use it to fix what you
> are working on.
>
> JohnL,
>
> This is exactly why I have 2ea - 77 (one was a gift from an employer -
> they didn't know it!) and an 87 in a box with some other goodies.
>
> I have the old 77 because I was doing technical acquisitions and the local
> electronics supply sent me a Fluke flyer that introduced the 70 series. In
> that flyer was a picture of a 77 that had just been packed into the ground
> by a 155x13 XAS Michelin (I just happened to know that tire well) and the
> caption said,
> "It is build to withstand physical abuse and the resistance scale is
> protected to 1000VDC". (My kind of meter.) I called my rep there and asked
> and he
> told me it would be 138$. I told him I would think about and he told me
> not to do that because they had 150 coming in and 137 had been sold. I
> asked
> him to put me on the list....
>
> I sometimes tell people that I have done two things right in my life.
> Those are buy my first house, and marry my first wife. We are on the fourth
> house.....
> Buying that 77 could be the third.
>
> 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
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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| Re: [GMCnet] The Importance of a Voltmeter [message #368272 is a reply to message #368225] |
Fri, 31 December 2021 19:49 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I bought 10 or 12 or of those (voltmeter only) out of China for under $3.00 each and occasionally handed them out to GMCers. I have 2 in my coach left on 24x7 for several years that monitor the engine and house batteries. I also keep one in my volt meter bag for quick checks when working on cars and airplanes. I have never had one read wrong or fail.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] The Importance of a Voltmeter [message #368286 is a reply to message #368225] |
Sat, 01 January 2022 20:44 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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So, related to this topic;
I DO have a volt meter AND an amp gauge, both installed by the PO, right next to each other. I have found that when I am driving with the lights on, and the heater or air conditioner, and the refrigerator on 12 volts (3 way Norcold), the voltage reads low, while the amperage reads high.
When I turn the lights off, the volt meter goes back up to normal, while the amp meter still reads somewhat high, but not as high as it did before, obviously because the coach is drawing less power without the lights being on. BTW, this condition throws off the factory electric gauges as well. The oil pressure reads a little lower and thew temp gauge reads a little higher, when the lights are on.
I understand the amp meter fluctuations, but I'm not clear on why the volt gauge reads low under a high current load. Can anyone with a better aptitude for electrical stuff than I (most of you) please explain what is going on?
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: [GMCnet] The Importance of a Voltmeter [message #368289 is a reply to message #368225] |
Sun, 02 January 2022 08:12 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Carl,
First, are you running a 3-wire (OEM style) alternator? or have you fallen for the one-wire alternator trap?
If you have a one-wire alternator, what you are experiencing would be normal. The alternator output voltage is regulated to maintain a constant voltage at the output terminal of the alternator. Any load current flowing from that point onward will create a voltage drop. So the higher the load, the higher the voltage drop withing the coach wiring. I'm assuming your voltmeter is likely connected to an IGN power source so it only reads voltage with the key ON and reads the voltage at that power source. As the load current changes, so will the voltage drop through the alternator power wires and you will experience dim headlights and slowing blower fan speed from the dash HVAC.
With the OEM 3 wire alternator configuration, there is a Voltage Sense connection within the wiring harness on the main power wires leading to fuse panel and IGN switch. This wire provides a feedback voltage to the alternator so that it can regulate to the desired chassis voltage present at the fuse panel and IGN switch. Any voltage losses (including the 0.7V lost across the Isolator) between the alternator and the fuse panel is compensated for by increasing the output voltage of the alternator. As the loads change, the feedback wire assures a constant voltage is available where most of the loads are connected (Fuse panel and IGN switch).
IF you have a 3 wire alternator and are experiencing a voltage drop above a certain load level, Your alternator might have reached its maximum voltage output. I would check this by measuring the voltage at the output terminal of the alternator. As you add loads, the output voltage should climb. If you find a point where your voltmeter drops when you add a load (ie. your headlights), I suspect you will find the alternator did not increase its voltage output. If so, what is the alternator voltage at this point? Some alternator regulators have a limited maximum voltage they will output for safety. OR you may have too much resistance in your alternator power wires (I found 3 splices hid in the wiring harness of my coach). I replaced the alternator power output wire to the isolator and removed nearly a volt of losses.
I would also check the voltage drop across the Isolator, it should be about 0.7-0.8 volts under any load. Shortly after getting my coach I had a chassis power issue which turned out to be a faulty isolator. The solder connection on the chassis diode side was just a glob of solder, not a proper connection.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] The Importance of a Voltmeter [message #368291 is a reply to message #368286] |
Sun, 02 January 2022 09:20 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Carl,
Bruce's explanation is (of course) real good but from your description, I wonder if that ammeter isn't installed in the alternator output. The original intent of vehicle ammeters (back in the DC generator days) was to know if the vehicle battery was being charged. That was always a serious concern. If the meter never goes positive, that is what you have. And, while that may be interesting, it is really useless data for the larger part.
Easy Test #1 - Turn the headlight on. Does the reading show negative?
If yes, if might be right
If no, then it is not a real useful meter
Easy Test #2 - If carburetor, don't set the choke.
If Fuel Injected, leave the headlights on a few minutes and shut off.
Now her fire up. Does the reading go positive?
If yes, it might be right.
If no, let it back to low idle and see if there is any reading at all.
I suspect you have an alternator output meter. They are interesting, but not real useful.
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: [GMCnet] The Importance of a Voltmeter [message #368295 is a reply to message #368291] |
Sun, 02 January 2022 11:19 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Thanks for the explanation. I think What Bruce said in his third main paragraph is the case. I do have the original alternator, three wire, but no isolator. The PO had replaced it with a combiner, and I just replaced that with an LI BIM as part of a LiFePo4 battery conversion.
The ammeter is hooked up in such a way as to read the load on the entire system. I can tell whether or not I turned my fridge back on after a stop, by looking at the ammeter. If it is reading less than 15 amps, I know I have forgotten to turn it on, if it is reading about 25 amps, it is on.
When the voltage is low, the amperage is reading high, in the area of almost 50 amps. When I turn off the lights, the voltage reads 12V+ and the amperage drops to about 25 - 35, depending on what is running. With the APU running, the amp gauge reads near zero.
Thanks again
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: [GMCnet] The Importance of a Voltmeter [message #368327 is a reply to message #368225] |
Mon, 03 January 2022 08:27 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I have 3 dead Flukes sitting here now. They were company issued and we had our own department to fix them. Because so many of them failed it was cheaper and faster to do it in house. We had several thousand of them out there and they were used daily. So when they failed you needed a replacement now. We kept about 3 spares in the office and the Centralized Parts Center kept some too. So you could get a replacement on the once or twice daily parts courier runs. They moved the repair facility called ICAR (Instrument Calibration and Repair) to the Centralized Parts Center for direct access to the Parts Courier delivery and pick system. You always got your original one back in 3 to 5 days. We did the same thing with Tecktronics Scopes but they seldom failed. They still got sent in for calibration annually.
Anyway, when I left I kept two Flukes, and Laurie kept one. They all 3 have failed in different ways over the last 22 years. I have no access to ICAR any more to send them in for repair. They are still used by field techs today. They were a good meter but for daily use their reliability is questionable.
I have found a Chinese meter I like better with more features like higher sample rate etc. Johnny Bridges put me on to them. I have 3 of them (home, Airport, and Pick up Truck) and have never had a failure. I have checked them for voltage calibration against my Scope and they have always been right on. At the time I got them for about $20.00 each. Now they are $30.00. I see them on Aliexpress for $25.00 to 35.00. Probably Bang Good has them too. At that price they are a throw away item if they were ever to fail. I ordered a total of 6 of them and gave away 3. One is a computer Networking Tech who uses his almost daily. One to a GMCer friend and one to my daughter. There may be newer models as this was a few years ago. Both Home Depot and Lowes had them for around $90.00
Peak Meter PM18C
Someone here on GMCnet said they got one that was defective at time. I do not remember the rest of of the story. I assume they got a replacement.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Mon, 03 January 2022 08:30] Report message to a moderator |
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| Re: [GMCnet] The Importance of a Voltmeter [message #368330 is a reply to message #368225] |
Mon, 03 January 2022 09:31 |
blur911
Messages: 166
Registered: December 2020
Location: Kingston, Ontario
Karma: 4
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I've personally never had problems with a Fluke meter.
I have an old Fluke bench meter, an 8060A, it was loaned to me about 30 years ago by an engineer when my Phillips meter blew up in the middle of a job, the next day he want back to Akron and I never saw him again. His replacement said it was a spare shop meter and not to worry about it.
Soon after I got a Fluke 76 which is a better field tool, it's very similar to the 77 but is true RMS.
More recently we all had to upgrade to CAT IV meters for safety reasons, so I got a Fluke 177. I like this one a lot, true RMS and it has a large backlit display with bar-graph and a setting to catch either highest or lowest readings which is good for troubleshooting.
I also have a Fluke hall-effect DC clamp-on and a cheap AC clamp-on plus many test probes and clamps/clips.
Cheaper meters are fine in some applications, but I'd rather have a Fluke in my hand when measuring 600volts and up.
Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model but we call her Roxie
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| Re: [GMCnet] The Importance of a Voltmeter [message #368340 is a reply to message #368327] |
Mon, 03 January 2022 18:21 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Ken Burton wrote on Mon, 03 January 2022 09:27I have 3 dead Flukes sitting here now. They were company issued and we had our own department to fix them. Because so many of them failed it was cheaper and faster to do it in house.
<snip>
Anyway, when I left I kept two Flukes, and Laurie kept one. They all 3 have failed in different ways over the last 22 years. I have no access to ICAR any more to send them in for repair. They are still used by field techs today. They were a good meter but for daily use their reliability is questionable.
Ken,
I am curious what you did to them to require such attention. Mine have not. (Well, things do happen.)
My oldest 77 is about 40yo and I had to repair the range switch a long time ago. I also blew a trace off the current measuring parts (my fault and I patched that and added a fuse). It is now a bench only meter just out of respect. The newer 77 is only a little over 30 and looks like new. I carry that in the coach. The 87 I got for a special client's needs and it and its kit is about 25yo, but I needed the true RMS and the Bell probe. That 87 had the display go bad and I bought an Ebay kit for about 20$ to fix that and on of the sections of the lead points went bad and that was another Ebay part.
Recently, I came across an jewel I just couldn't pass up. 40$us from Amazon. A Thsinde ACM1 says it does DC current as a clap-on! I have not had a chance to check that out. I do not like the display (no fast bar graph and the decimal gets lost) and it never seems to sit down so I can see it, but if I should loose it overboard, I won't cry either.
I used to give away the Hazard Fright cheapies to clients that didn't have a meter onboard. He would look at it and tell me he didn't what to do with it, and I would say when you call me (they all have my work number on the side), I can tell you what you need to do and know. For that reason, I carried one in my own kit so when we had to do the diagnostic over the VHF or telephone, I knew what he had. It worked very well more than a few times.
We are cold here now, so I'm going to have to get the coach into the barn soon.
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: [GMCnet] The Importance of a Voltmeter [message #368370 is a reply to message #368225] |
Thu, 06 January 2022 11:06 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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I've got a Fluke clamp - on with leads and several scales for voltages well, but the most used is the $8 Hashimoto Mouse one I got off eBay. They were sold under several names. And were famous for being intermittent. A bit of investigation showed that the safety covers on the probe plugs were a bot too long. I've now resurrected several of these with an X-Acto<tm> by trimming the plastic back about an eighth of an inch. They have a display which dies in sunshine so if you have one keep it out of direct sunlight.
That being said, I was at Ken Henderson's place helping with a coach which wouldn't keep the battery up. No help from a voltmeter, charging voltage was 14 and a bit, but the coach would sag on the road for lack of spark. Ammeter to the rescue, we determined the battery was drawing way too much current. Took it out an hour after running it, and the battery was still very hot to the tough. Since there's a warehouse for that brand in the area we took the battery down there. The guy remarked on it being warm even then. One of the interior cells was failing. It was a week or two out of full warranty but they honored it anyway ad gave us a new one. An ammeter would have shown this at first crank up and saved a bit of troubleshooting time. Yes, I'm old fashioned.
DOS Tip: Put your ammeter in the gr4ound lead of the battery, it's safer
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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