voltage question

When driving my car, the voltmeter reads at least 14 volts but at night with the lights and radio on, the voltmeter reads 12 volts. Does that seem within a normal range? I have an MSD ignition. Thanks, Paul

 

The usual factory specs for charging voltage is 14.1 and with your headlights on 12 sounds just about right.

 

It is an internally regulated alternator. Do you think it's on the way out???

 

The Stewart Warner gauge is at least 30 years old. I have XM radio I play by plugging it into the cigarette lighter through the radio. At night while driving, the headlights are bright and in the day, as the rpms go up, the volts go up accordingly to 14 volts.

 

I'll do that. Thanks for the tips. Paul

 

old wiring when the lights are turned on will draw more voltage because of the increased resistance in the aged wiring.

 

not that big of a voltage drop.. 2 volts is a big drop, old wireing wont cause a drop like that but a corroded or a poor conections(resistance) will cause it. double check all your connections, check your grounds and check your alternator.check for that blue/green corrsion.. 13.5 under a load should be the lowest, its never a bad idea to upgrade to a nice powermaster 140amp altenator. i run one in my 53 international and one in my 66 lark with a turbo nailhead. i run a a1000 fuel pump, electric oil pump, electric trans fan, msd dist and headlights and it is @13.9 -14.2. good luck

paul
66larkgs
turbo nailhead

 

I'm going to be ordering up one of these: http://www.qualitypowerauto.com/catalog.php?item=10 and the wire kit: http://www.qualitypowerauto.com/catalog.php?item=81 .

I'm also going to install one of there starters: http://www.qualitypowerauto.com/catalog.php?item=103


:TU:

 

It maybe that your gauge is just worn out being that old.

Check it as LARRY70GS said and replace the gauge with a new one.

Heck you can pick up a triple gauge for around $50 to $100's that will give you oil, water and volt's.

 

Well after seeing Jamie's work and thread I'll have him do up a alternator and wiring kit for me as well as a starter, it looks like it will be cheaper to have him do it over what it would cost me to buy the stuff from Quality Power Auto .

Thanks for the link Larry :TU:


http://www.v8buick.com/showthread.php?t=89861

 

... not only that but you support a member of this board who also helps it keep going as a paying vendor

Plus - Jamie is a Heck of a good guy. I'm running one of his starters

 

Good advice. Thanks guys!

Paul

 

Had the car out today and it's time for a new gauge! At 750 rpm idle with head lights and everything on in the car the gauge shows 12 volts but my voltmeter reads 13.7 volts at the battery. With everything off at idle, the gauge shows 13 volts but the voltmeter at the battery is showing 14 volts.

 

It sounds like the battery voltage hardly varies, but voltmeter varies
with load. That load drop might be caused by voltage drop in the wiring,
on the way to the voltmeter.

Don't buy a new voltmeter, till you check the voltage at the voltmeter
terminals. If that is low, the upgrade should be on wiring. Bruce Roe

 

That makes a lot of sense! Thanks for the tip.

Paul

 

Something to consider here is the loads we add to the system as we further enjoy the car. These added loads, however, make the alternator's job increasingly difficult. Added loads require increasingly higher current capacities for the alternator. Though these alternators are available, the issue is frequently similar to camshafts. Added power from the engine from the cam is available as the rpm increases, but the performance at lower rpms suffers. It is that way with alternators as well. As we increase the current capability from the laternator, less current is available at idle. There are some options, including the smaller alternator pulley, raising the idle speed, or a device for stabilizing the voltage as alternator rpm drops. The least expensive alternative is the smaller alt pulley.
If the voltage increases to about 14 volts just above idle, the problem is likely one of alternator rpm, not capacity. Ray

 

Ray, you say the idle current output of an alternator decreases as
it is built for higher maximum current? I hadn't noticed that. But
that would not apply if a physically larger alternator was used,
increase across the board. I've been using the larger diesel
alternators, and my 79 EFI Cad came with a huge alternator.

What is the device for stabilizing the voltage as alternator rpm drops?

Bruce Roe