(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

[MEXICOWANDERER]

The 2500-2600-2700-2800 Leece are within the same housing. the 105-130 amp versions use a slightly smaller rectifier heat sink.

model# A001090772 is a PRESTOLITE number for this Leece

Digital multimeter time

Chop chop 🙂

[Cloud_Dancer]

Not that it helps, but I found in my notes from years back when you all helped me diagnose my one-and-only electrical problem (up to this one):

Leece Neville alternator
model# A001090772
service# 2824LC
sales# 90772
160 amps

It took me forever to find a couple of chassis batteries with most recent shipping date. I ran around to all the Sam's Club stores: Energizer Commercial group 31, 950 CCA by Johnson Controls Battery Group
Price: $99.88

I had decided to first install all new batteries, THEN start the "walk you through" trouble shooting. I'll report later. Thanks

[MEXICOWANDERER]

Take a close look at the smaller studs with nuts and labels. The one on the left says IGN. This is a key signal to instantly energize the voltage regulator. Hence the "low turn on".

The terminal on the RIGHT is labelled REMOTE SENSE. Therefore this is NOT a so-called "one wire" alternator.

The voltage AT THIS TERMINAL MUST BE EXACTLY THAT AT THE BATTERY BANK. If this terminal voltage is LOWER than at the battery bank the alternator voltage will rise.

Therefore my guesstimate that you have a 2500 - 2800 series JB is incorrect. The 79000 voltage regulator part number is similarly incorrect.

You absolutely must determine if there is a VOLTAGE DROP between the alternator output stud and battery bank. And similarly between the alternator bolt left side NEGATIVE stud and the vehicle engine then the vehicle chassis.

Most of these checks can be done right at the rear of the alternator.

There is a frighteningly high percentage of possibility that NOTHING is wrong with the alternator and voltage regulator, and the real problem lies in the voltage sensing wire and connections. If the voltage at the alternator positive terminal and the voltage sense lead terminal read the same or very close, the regulator would then be BAD. If the positive terminal reads >.3 volts than the sense terminal then the sense lead wire is bad. Theoretically this sense wire should be connected to the CHASSIS battery positive terminal. They may have connected it to any terminal in the main starter cable routing. Don't screw with it - there are lots of places to connect this wire. In a pinch run a wire between the sense terminal and main alternator + positive (5/16") bolt output terminal.

Leece Neville (Actually Prestolite Co.) tried to get cute and access remote voltage sensing for line loss compensation to the batteries.

In a HEARTBEAT I would TRASH this regulator and convert to a Transpo 79000S or 79000HD regulator. The Leece Neville 79000 regulators do not turn on at low engine speeds, the Transpo regulators do just that. LN voltage regulation design has always been their weak point.

To try and compensate for disaster level volt-drop in the main charging cables is STOOOOPID*. Fix the cables. Prestolite screwed up the LN alternator the moment they bought out the company. Prestolite couldn't screw up the Motorola 10-255 J-180 foot alternator any more than Motorola had from the get-go misdesigned it before similarly selling out to Prestolite.

Marion Hovermale listened to me about remote sensing in the Delco CS series alternators and the regulators were redesigned to automatically switch to INTERNAL ALTERNATOR VOLTAGE SENSING if external sensing is compromised.

Grab that hand-held multimeter! I will walk you through the troubleshooting and the fix, step-by-step.

[MEXICOWANDERER]

The OP has a Leece Neville J180 mounting

T R U C K

alternator. The 79000 series ADJUSTABLE voltage regulator CAN NOT BE ADJUSTED HIGHER THAN 14.8 VOLTS.

Someone had better re-check their facts. NO and I mean ZERO NONE alternator voltage regulator regulates at 15.0 volts or even 14.8 volts. The lone exception was the 15SI Delco 1116405 voltage regulator which had a setpoint of 15.0 volts at 20c. It was soon obsoleted when lawsuits hit Delco. The idiots designed the reg for use with it's proprietary Calcium Calcium Delco battery which cost almost twice as much as an aftermarket non calcium battery and was inferior in all respects except cranking CCA. This regulator boiled regular batteries dry. The class action lawsuit was filed in Lansing, Michigan in 1979.

Few if any of today's integral or ECU voltage regulators are not "temperature compensated". This is acheived by placing a THERMISTOR within the voltage regulator voltage divider voltage sense network.

At 70F, the maximum deviation allowable is in the neighborhood of 14.2-14.3 volts which soon slumps because of coolant radiator BTU emission, or stator/rectifier thermal buildup OR engine radiant heat. Today it is not uncommon to see voltages of 13.7 - 13.8 when the engine is warm. Starting an engine on Christmas Eve on the North Slope of Alaska, the thermistor allows a regulated voltage peak in excess of 15.0 volts.

I was fascinated by the performance of my MoPar ECU controlled voltage regulator near Lukeville AZ on the 10th of August 2010. At 122F ambient temp, with an engine temp of 242F, the regulation setpoint backed off to 13.18 volts.

REGARDLESS

There are no, none, zero, absence, of alternator voltage regulators that at 70F regulate at 14.9 - 15.2 volts. Please recheck facts.

[jauguston]

Modern automotive charge systems nowadays have a maximum charge voltage of 14.9-15-2v. That is NORMAL. My Full River 6v AGM house batteries recommend a 14.9v charge rate.

Jim

[Cloud_Dancer]

W0W!
I believe that my alternator is a Leece Neville 2824L Duvac. The alternator mounts into a box recess that's cast on the top of the rear housing. It's held in with 4 screws and has 3 terminals/wires. It also serves to hold down the springs of the 2 brushes. Here's what they say about this regulator:

Solid State Low Turn-On Voltage Regulator, Maintains Consistent Voltage even when Hot

They say this alternator is the most popular unit used on diesel pushers, and a variety of service trucks.

[MEXICOWANDERER]

The charge rate at the batteries is sufficient. The JB series alternator like all other LN units, uses internal voltage sensing. Tiny red and black wires connect to positive and negative rectifier heat sinks respectively. The Diode Trio is external mounted between the white brush housing and rear alternator bearing. The trio only serves to turn the regulator on, and does not pass total rotor current.

DIASSEMBLY
The 7/8" rotor shaft has a woodruff key so you can hold the pulley and use a 15/16" socket to remove the pulley nut then washer.

The woodruff key must be removed to slide the rotor through the double wide 6305 front bearing. The Urea based bearing grease sometimes makes the sliding process difficult. Lacquer thinner works best to dissolve this grease but the entire snout of the alternator must be immersed to penetrate between the bearing and the shaft. This destructs the bearing which should be replaced anyway. Remove Pulley, fan, and spacer.

Use a 5/16" socket on the head of the case bolts and a 3/8" socket on the #10x32 nylock nuts on the rear of the alt. The alternator splits with the wide stator laminations staying with the REAR half of the case. Some separate easy, others need patient encouragement with a knife-edge flat screwdriver tapped into the space between the last stator lamination and front housing.

Separate the rear housing with stator from the front housing with rotor. The brushes will fall out now.

The rear Torrington type rear bearing should be replaced. You'll notice the LN slip rings are brass rather than copper. I like that. They are harder and wear better than copper.

Grab your camera and take several clear images of the inside of the REAR housing. Pay special attention as to how the 3 rectifier leads to the positive side and the three rectifier leads from the negative side thread their way up to the three stator connection screws (nuts) which are through-bolted through the plastic brush holder housing

Remove the three 3/8" nuts holding the three stator leads to the nuts above. Pry the stator ring terminals off these through bolts.

The stator is ready to be removed. Like before it will either almost fall out or you will need that knife edge screwdriver again. Remove the stator.

More images. Double check they are clear as crystal.

Remove the two voltage regulator wires using a 1/4" nut driver to remove the screws. The voltage regulator is now ready to yank out.

Undo the different size battery terminals. The bolts are carriage type. The positive outside nut is 1/2" the negative is 1/4". Slide the bolts out.

Remove the 2 1/4" head screws and hold down clamp for the yellow capacitor using a 1/4" nut driver. /Remove the capacitor.

Sometimes the bottom screws holding the rectifiers are flat blade slotted. Remove one screw. Carefully lift the rectifier and detach it's three ring terminals and wires from the same three studs as held the stator leads. The rectifier is black and arc shaped. CAUTION! There are insulators on both sides of the bottom mounting hole. Remove them, leave them in place, but do not lose them.

Try not to disturb too much the lay of the original rectifier to ring terminal wires. it makes for a good pattern to follow if you replace the rectifiers. Remember, new rectifiers need their wires trimmed and new flag terminals soldered on.

The rectifiers for the Leece 160-amp alternator are different from smaller amperage JB's and are not interchangeable. The individual rectifiers are not something you want to try and change. Buy the complete rectifier.

STUPID STUPID. Leece should NOT have painted the aluminum rectifier heat sinks but they did. Heat sinks should have been black anodized -grumble, snarf-

Assemble in reverse fashion.

Spin the almost reassembled rotor. if it catches on something, it will be on one of the rectifier wire leads. Take the housing apart and rearrange then clamp the two halves together and try again. MAKE SURE the housings are not slightly cocked on the stator lamination shelf. If necessary clamp tight with the through bolts. Patience Patience.

I've done 200-300 of these critters so I can reman one on my sleep. A couple of weeks ago a friend snorted when I mentioned the 10,000 units rebuilt. His reply: "Try 15,000 to 20,000. Remember the marathon 42 Delco units you did in a single day?"

Getting old. Too many things to remember...

[Cloud_Dancer]

MEXICOWANDERER wrote:
You have a Leece-Neville part # 79000 voltage regulator. Verify your voltmeter is not lying to you. Go online eBay and query 79000 voltage regulator. Transpo brand HD model is good. These are flat compensating regs so LN decided. No temp adj slump. LN brushes for the 2500 series JB units are long. I never liked OEM 79000 regs so I used Transpo with good luck. DO NOT use a reman alt as they are JUNK except for the Prestolite Leece-Neville remans available at big rig manufacturer's parts counters. Stick with Transpo for regs and OEM for new or reman units.

Thanks. I wrote that if the new chassis batteries end up having no bearing on my problem, that I would simply replace the voltage regulator. I reasoned that it was obvious that the charging part of the alternator was working, therefore it has to be something telling the regulator that a high charge rate is called for, OR the regulator has failed somehow. Yes, the brushes are long, I replaced them a few years ago (one of them was broken in half). But, the symptoms then were quite different than what it's doing now. Thanks again, and I'll report later (I'm off to Sam's to purchase a couple of group 31 RV/Marine batteries).
Oops, I'll verify the high charging rate at the alternator (not an easy check). I'll check it at the batteries first.

[MEXICOWANDERER]

You have a Leece-Neville part # 79000 voltage regulator. Verify your voltmeter is not lying to you. Go online eBay and query 79000 voltage regulator. Transpo brand HD model is good. These are flat compensating regs so LN decided. No temp adj slump. LN brushes for the 2500 series JB units are long. I never liked OEM 79000 regs so I used Transpo with good luck. DO NOT use a reman alt as they are JUNK except for the Prestolite Leece-Neville remans available at big rig manufacturer's parts counters. Stick with Transpo for regs and OEM for new or reman units.

[ScottG]

I wrote that the voltage will be a bit lower if it's very hot (especially if the battery is in the eng compartment) because they don't like higher voltage when they're hot.

I don't blame you for replacing batteries when they get older.
I've been driving for about 40 years and twice in that time I have had older battery's suddenly short internally and leave us sitting (cant jump start them). The last time was just a few years ago on a used car I bought.

[Cloud_Dancer]

westend,
Are you referring to this post?
*
"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."

Yes, it's been very hot. And, my motorhome has spent most of its life (13 years) in the sun belt, from Arizona to Georgia. I'm the only one who has driven it. I've jumped in it when the weather is HOT, and have started it many times, as you can imagine. I always check/monitor the instrument panel meters/gauges right after it starts. THIS is the first time the voltmeter has gone that high, and this is the first time is will NOT go down, at all, no matter how long I run it (within reason). Therefore, I simply have to find out the reason. I'm not going to do nothing, I gotta do something. Right now, I'm simply going to try to eliminate the possibility of the problem being a bad battery. Out of six, batteries, I've got 2 to go. Then, I'll report back. I feel I owe it to everyone to do at least that.
But, I've got to ask, what would you do? OK, I see what you would do. I've already cleaned all the cable-to-battery connections (many), and I've checked the battery voltage, separately with cables disconnected. These two batteries are a bit over 6 years old. That's about the interval that I've always changed the batteries, anyway. Why not now?

[westend]

My Ford Trucks charge 14.2- 14.5V and it is hard to run the same battery for longer than 6 years.

The conclusion you reached, that higher alternator voltage is responsible for lack of battery longevity, is not the same as the majority of automotive engineers designing 12 V systems.
The optimal charging situation is to recover from high starter draw and return the battery to a full SOC as quickly as possible.

FWIW, the original, slightly abused Motorcraft battery installed in my '03 Ford Superduty was replaced at 10 yrs., one month.

I'm sorry to hear that the OP discounts the information related before his last post. There are many members on the Forum that have rich technical experience. Maybe he's in search of a different answer?

However, I don't discount observation and if CD noticed an abnormality in his gauge readings, an investigation would be prudent. Since alternator output is proportional to battery acceptance, a tuneup of the battery and the connections would be my first step. I'd suggest to remove and clean all the connections to the battery, clean up the case, and charge the battery overnight at a small amperage charge. At the next start sequence, the gauge may read that the voltage is lower. That would indicate that the battery, in the previous observed abnormality, was slightly discharged more than normal and the alternator was operating correctly.

[time2roll]

My alternator gauge never moves. Until it did two years ago and it was the alternator.
Doubt you have a battery issue.

[scrubjaysnest]

Cloud Dancer wrote:
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

That is normal and GC-2's need 14.8 to properly charge anyways.

[Kayteg1]

I have feeling that about 40 percent of batteries are disposed still having lot of life in them, only because the "Oil change 3000 and battery replacement every 4 years" mentality takes 50 years to shake off.
Our family fleet had several batteries lasting 12-13 years, where one of the myths is that CA heat kill batteries prematurely.
I also hear about car batteries lasting 17 years and those are reliable reports.
Latest technology makes pocket-size digital battery testers that IMHO each RV owner should have. I still have old boxy load tester, so hold on spending money on new technology.
Than battery charging is whole science. Seems topping-off does harm them.
My 2-years old computer come with 4 different programs for charging (those are different types batteries, so not all principals are the same)
So the first choice of having batteries fully charged come with warning that it will shorten their life.
I choose longer battery life program, that will not start charging till batteries drop below 80 percent .
Comparing flooded batteries. Our Mercedes cars don't charge higher than 13.9V and those are that can run on the same battery for 12 years.
My Ford Trucks charge 14.2- 14.5V and it is hard to run the same battery for longer than 6 years.