Been having weird issues with battery and/or charging. I purchased a voltmeter that plugs into cigarette lighter and reads battery charge level and also state of charging system while running. It appears that my alternator is at times charging and at other times not charging the system - what would cause this? Diodes? Voltage regulator brushes are fine, belt is tight . . . . . I swapped out old battery with new group 49 battery - weird!

I have an analog Volt Meter and a Digital Volt Meter that plugs into the Lighter Socket.

It simply could be that the Meter is not making good contact inside of the socket or the Lighter Socket has some issues. You might check the Fuse that goes on that circuit.

Also I find that the Digital One that I have uses up about 1 Volt to run itself.

If you had a regular Volt/Ohm Meter you could check it against the plug in one.

Is there any sort of pattern as to when it is not charging like it always does not charge at idle speeds?
Also what other electrical stuff is running during the test?

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84 300D, 82 Volvo 244Gl Diesel

Sweetie's car did similar.

Swapped regulator with know good. No change. Swapped alternator with known good. No change. Swapped back in other known-good regulator. No change.

The culprit? Crapped up newish "improved" glow relay, failing to release. The alternator isn't strong enough for continuous glowing.

YMMV.

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James Marriott
2003 Buick Regal
1983 300D (228k, frau Auto)
1996 Suburban K2500 (192k, 6.5 turbo diesel/4WD towmaster 10,000)
www.engineeringworks.biz
1987 300SDL junker 170k
1982 300SD junker, 265k

I have a quick glow system with a Ford Solenoid setup - I wonder if the solenoid could be occasionally engaging and failing to release?

Damn, alternator shows charging (did yesterday) via my onboard gauge and then last night, no charge on the drive home. Battery capacity was down too on start up so it appears that current is still being drawn off somewhere and that my alternator has some issues - wonder if its a diode issue?

Cheepie digital meters can be had from ebay at under $10. Ive used them for years and they just work.

Stepping on them if they are on the floor and smashing the leads into the meter is NOT recommended, they seldom work after that.

My alternator was intermittently putting out about 13.8. Drove over to a buddys place who has a really nice shop. There at ~2000rpm the 'output' measured ~12.6, indicating an alternator that wasnt putting out. The new unit put out about 14.2.

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

I've had a digital cigarette lighter voltmeter put out all kinds of funky readings. The voltmeter was bad. Don't take it for gospel.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Thanks! I am beginning to think that the solenoid is sticking and drawing off large amounts of current which makes the alternator appear to not be doing its job. I thnk it stuck last night and while driving, I hit the manual glow button a few times which seemed to deactivate the draw and then the volts measured were normal (13.6+) Weird!