(FINAL Update )...Alternator voltage too high, question

[Cloud_Dancer]

Mine is a 2003 Spartan chassis, 8.3 350HP Cummins engine, Leece Neville HD alternator with integral voltage regulator. It set at the lake for a month, hooked up to shore power, and I went to check it out, cranked right up, but but the dashboard voltmeter started showing 14.5 to 15 volts. I had never seen this before. I checked the 6 years old house batteries, one was weak, replaced all 4 (golf cart 6 volt). NO change. Tried it with shore power disconnected, no change.
Question: What's the best guess? Change the 2 chassis group 31 batteries, or is it the voltage regulator? Thanks

[landyacht318]

My voltage regulator in my engine computer would allow 14.9v, but the range it allowed was 13.7 to 14.9v

14.9 being too high and often it would choose 13.7 when battery was still far from fully charged had me bypass this voltage regulator and add an adjustable one with potentiometer on dashboard next to voltmeters whose voltage sense lines are right on battery terminals.

So I choose, and generally leave it at 14.4v until I know battery is fully charged or battery is above 87f, then I lower it

I understand the gauge reading different is a red flag to you. I'd double check the gauge. and the connections on back of alternator and firewall grounds.

And get a can of Caig Deoxit d5 spray for any connectors you open. no other electrical contact cleaner comes close. The presence of dielectric grease does not mean the conducting surfaces are 'just fine', as so many people seem to think.

[Cloud_Dancer]

OK, there's lots to be said about dash voltmeters. But, normally all I use it for is on my panel scan as soon as I start the vehicle, and if I detect a change from normal I look into it. To me, in a vehicle that has only been driven by only one person (me) the accuracy is not as meaningful as detecting a departure from what I consider normal. This time, something is not normal. I only visit troublshooting electrical problems very infrequently. In this case, ONCE in 13 years. This is the second time. I'm calling for help from those who know what they're doing. Thanks

[ScottG]

Unless it's very hot out, the voltages your seeing are correct and normal. If you manage to lower them you won't be doing your batteries or anything else any favors.

[CA_Traveler]

Replacing 6 year old batteries is a good plan. But a load test might be revealing.

I know that my cab voltmeter does not reflect the battery voltage and the reason is obvious. Typically the cab voltmeter will be connected in the cab area and there can be voltage drop between the cab and the batteries due to all of the loads.

[Chris_Bryant]

You might also make sure the gauge isn't off.

[Cloud_Dancer]

RoyB wrote:
I see the 14.2-14.4 all the time when I first start-up my Ford truck. Then it starts tapering back to the mid 13's as I drive... The Truck Start Batter seems to work well doing this...

When my truck is setting I see 12.5VDC most of the time on the VOLTMETER. They all seem to have going on all the time...

Roy Ken

I've had this unit since new, and it has never indicated more than 14. Yes, a few minutes of running has always brought the voltage now. If anything, this one goes up a little bit. It's definitely not normal.

[RoyB]

I see the 14.2-14.4 all the time when I first start-up my Ford truck. Then it starts tapering back to the mid 13's as I drive... The Truck Start Batter seems to work well doing this...

When my truck is setting I see 12.5VDC most of the time on the VOLTMETER. They all seem to have going on all the time...

Roy Ken

[Cloud_Dancer]

What I meant by integral voltage regulator is that it mounts on/in the alternator. But, it's easily removable/replaceable. A few years ago I had the alternator off, because it quit charging(was giving out weird symptoms). I found one of the brushes was broken. A new set of brushes fixed everything.
The chassis came with a good inverter/smart charger. It's always worked great, on shore power or generator or boondocking.
Because I've come to really trust the dash voltmenter, I'm leaning into first changing the chassis batteries (mostly on the basis that they are 6 years old), and in hopes that it'll solve the problem. Also, I've got multi-meters, but I'm just not that good on troubleshooting circuits.
If replacing the batteries does not change anything, I probably will change the voltage regulator. Yes, sometimes I'm a parts replacer instead of trouble shooter. But, in this case, I can justify the cost of parts because of the age and service I've gotten from the batteries and the voltage regulator.
But, if you think of something else, please post it. It'll take me a couple of days to do the batteries, but I'll report back. Thanks

BTW both chassis batteries indicate right at 12.6 on either one of my multi-meters (batteries disconnected from each other). It's just that I've seen weird things with old lead-acid batteries.

[CA_Traveler]

First load test the chassis batteries as they may be the primary influence on the alternator. And at the same time confirm the voltage at the chassis battery with a known accurate voltmeter. Bulk charging rates for flooded batteries are 14.4-14.8V.

Next disable the isolator so that the house batteries are not a factor and check the voltage.

It's possible that what you are seeing is OK and the voltage will drop as the batteries get charged.

If your charger doesn't charge the chassis battery then try a portable charger on them then check the alternator voltage (give it some time).

[westend]

Chassis battery sat for a month and you cranked over the engine and your voltage gauge showed 14.5 V? That is all entirely normal. I've measured some gas engines at the same voltage immediately after starting.

Run the engine and if your chassis battery is good, you should see the voltage gradually diminish to 13.5 V or so.

Mex may chime in to tell you exactly what that alternator is rated for.

You may want to confirm the accuracy of your gauge with a handheld meter. They can be off by a small amount.

[Kayteg1]

ALL VR I have seen are replaceable.
I know shops don't like to replace $40 VR and will rather take their mark-up on $1000 alternator, but smart owners will not fall for it. Alternator bearings last very long time and the only wearable are brushes.
Going back to the voltage, double check it. Occasionally on discharged batteries the voltage can go high for some time, but for normal operation above 14V will shorten battery life.
Also confirm dashboard gauge with different one.

[tvman44]

Voltage regulator and since it is internal to the alternator, time for a new alternator.