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Charging rate issues?

Driving to the coast from our summer spot, the first leg was about 3 hours. During that time the dash/analog (chassis battery) gauge was slowly creeping up from its usual 13 - 14 rate to being close to 15 by the time I parked it. A search of the forum suggested solutions from replacing the alternator/regulator (Brown alternator with a Leece-Neville 79000 regulator). I removed most of the cables from the battery isolator and did a much-needed cleaning and reattaching so the connections could be assured. Much happier with the result when I set off the next day as the voltage was nicely about 14.4. Gradually through the long day of driving the analog gauge crept up, as did the digital (house batteries) read-out. Driving with lights and fan on, and later with interior lights on as well, helped slow the gradually increasing voltage readings, but by the end of the third leg (another 5-6 hour day) the analog gauge was flirting with 16 volts. I was getting more anxious about over-charging my one year old batteries.

My amateur diagnosis is that the alternator needs to be rebuilt and the regulator needs to be replaced as part of the charging assembly. The intent is to get reliable and correct performance from the charging system.

Any thoughts about the direction to take? I now have the alternator/regulator removed from the engine (and discovered longitudinal split in the serpentine belt during the removal process), so belt replacement is facilitated by alternator removal. IF the belt had been slipping. or otherwise being a problem, I assume that I would have seen under-charging, not over-charging.
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Charging rate issues?

Reply #1 –
A completely unrelated question to your electrical question.  What is a " basement model".

 Sorry, I don't do electrical stuff, unless I'm simply replacing something.
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR

Re: Charging rate issues?

Reply #2 –
I would say a new or rebuilt alternator is needed. 
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Charging rate issues?

Reply #3 –
Quote from: Mike_Sandra_Lloyd –
1. I removed most of the cables from the battery isolator and did a much-needed cleaning and reattaching so the connections could be assured.
2. My amateur diagnosis is that the alternator needs to be rebuilt and the regulator needs to be replaced as part of the charging assembly.

Woody,
During your cleaning did you clean the sense wire connections at both ends (at the isolator and on the alternator terminal)?
 OEM this wire was hooked to the 15 amp breaker that feeds the A/C compressor on the isolator board. Several of us have moved this wire to a better location as this location is on the down stream side of the breaker (which is to protect the wire).  Due to location of the breaker out in the elements it build resistance as it ages giving a false reading to the alternator voltage regulator. This can be the cause the symptoms you are having rather than a bad alternator.

I am going to say the alternator is doing what it's job. It just don't know what the true voltage in the system is. Before you have the alternator rebuilt (and the shop don't know the first thing about a DUVAC system) and open another can of worms do the simple stuff first.  At 16 volts the alternator is working so the internals should be fine. It could be the voltage regulator going bad which is pretty easy DIY job along with a set of brushes while you have the regulator off. Yes the brushes are under the regulator. If you get this far let me know and I will walk you throught the replacement.

Mike

Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Charging rate issues?

Reply #4 –
Mike (Pam & Mike) - I did not get at all of the wires at the battery isolator when I did my cleaning in September. One of the wires (small, therefore likely a sensor wire) was quite stuck and as I was using a single wrench on the bolt I saw that the stud was just starting to move so I stopped. I realized later that I needed to have two wrenches for the job, one to brace the nut below and one for the nut above - but did not get back to it before we had to leave the next morning. The wires at the alternator were, likewise not done as they could not be accessed and I didn't then have the wrenches to remove the alternator.
Your suggestion to do a thorough house-cleaning of all cables and wires makes a lot of sense - and is a good reminder to follow the K.I.S.S. Principle, since I have had a tendency to do the hardest most complicated thing first, and sometimes pay the price for it. I am pretty sure that I can easily find the Leece-Neville regulator, and presumably can also find the needed brushes, so we will be in touch as the project progresses.
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Charging rate issues?

Reply #5 –
I will also try to identify the "15 amp breaker that feeds the A/C compressor on the isolator board" and see what I can do about that. Problem-solving certainly leads to greater knowledge :-).
Woody & Sandy Lloyd
1993 Grand Villa
Unihome U280
Cummins / Allison
Build # 4379

Re: Charging rate issues?

Reply #6 –
Those 15 amp breakers are available at most any part store. By what you just described I would plan on installing a new one as you may twist off the stud during removal and cleaning.  Expect to pay ~ $3 or 4 for it. The brushes can be got at most any alternator shop or off the net.  You will need a round toothpick to hold them in place while you are bolting on the regulator.

If you twist off the stud  on the back of the alternator let me know. You will have to pull the brush holder to replace the bolt but not a big hill for a stepper.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Charging rate issues?

Reply #7 –
Quote from: Mike_Sandra_Lloyd –
I will also try to identify the "15 amp breaker that feeds the A/C compressor on the isolator board"...
Mike (Woody),

If you look at your B-2126 wiring schematic, in the bottom left corner, you'll see the circuit breaker to which (the other) Mike refers.

On your isolator panel, there should be the isolator + two solenoids + two 15A circuit breakers + one or two relays.  See photos below.  Breakers are on the bottom left of photo, hidden behind all the wiring.

Your alternator sense wire might be connected to either of the breakers, or to the AUX START solenoid, or to the BOOST solenoid, or to the engine start battery post on the isolator.  As long as it "sees" start battery voltage, doesn't really matter.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Charging rate issues?

Reply #8 –
Have had both done,rebuilt the LN for more then the cost of a new 160 amp Delco 28s,the rebuilt did not last long,unless they
put in every part new it's only as good as the weakest part no matter what the shop tells you.Much better performance from the Delco.Also redid the isolator and board at the same time.Have the exact board you have,replaced everything.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Charging rate issues?

Reply #9 –
Quote
Several of us have moved this wire to a better location

Woody,
  If you can find that sense wire that Chuck is referring to (labeled E-59 and white in color) just hook it directly up to the positive post on your start batteries. This is what the forum suggested I do and it cured the problem. Cost to the consumer: $0. Here's my notes from when I was cleaning connections on the alternator fyi. Good luck.

Quote
There are two small terminals. The outboard is E6. It is the Exciter. The inboard one is E59. It is the Voltage Sensor. It goes to the 20 amp circuit breaker on the isolator board.That circuit breaker goes to the Start solenoid.

Here's a photo of the isolator board on my 97 before I moved it. I think that white wire that the arrow is pointing to was the sense wire. You can just peel back the loom material, clean the wires and you'll see the numbering.
93 225
95 300
97 270
99 320
 

Re: Charging rate issues?

Reply #10 –
After the engine has heated up, get a voltmeter and measure the voltage at the alternator sense and output wires. If you are using a standard Foretravel-configured dual diode isolator, there should be .6 VDC difference between isolator input and output. This is a typical silicon forward bias voltage.

The alternator needs to output .6 VDC more than the batteries will see. E.g. 13.6 + .6 = 14.2 VDC.

I know this because my sense wire was wired wrong because truck technicians had no idea what they were doing.

Then again, there could be wiring lug looseness, contact corrosion or bad parts (isolator diode, regulator or alternator.
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.