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

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...

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.

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

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.

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.

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

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 :)

I'm back! I was sidetracked with a weird starter-not-cranking problem. Read about it in the Class A Motorhome forum. I got help from Tom/Barb.
*
New chassis batteries are installed, checking close to 13 volts. I managed to attach clip leads to the alternator output terminal/post (+) and to the Remote Sense terminal/post. With everything off, alternator(+) lead indicates 12.76 V, and remote sense lead indicates 12.77 v.
With engine running at idle, dash voltmeter indicates 14.9 to 15.3 volts. Alternator (+) lead indicates 15.9 to 16.5 volts. Remote sense lead indicates 16.6 volts. I shut down the engine (the voltage wasn't decreasing).
Other than a few years ago, removing the alternator, removing the voltage regulator and replacing the brushes I simply don't have enough experience with symptoms vs remedy. Off the top of my head I tend to lean towards replacing the voltage regulator. But, I will wait to hear from MexicoWanderer and otheres. Thanks

Voltage regulator is what is says.
Most of us associate it with alternator brushes, as that is the only way in US to buy, but the unit has electronic circuit inside as well.
When the circuit fails - whole thing needs to be replaced (you can save good brushes for re-soldering them next time)
With readouts >15 V there is not much to think about.

Kayteg1 wrote:
Voltage regulator is what is says.
Most of us associate it with alternator brushes, as that is the only way in US to buy, but the unit has electronic circuit inside as well.
When the circuit fails - whole thing needs to be replaced (you can save good brushes for re-soldering them next time)
With readouts >15 V there is not much to think about.

Not clear on what you wrote. Are you saying it's open and shut, the voltage regulator is the culprit?