voltage ranges from 13.8 to 16 volts

[Jeremy Parrett]

I have a Beaver Marquis Amethyst 2000, with a Cat 12 450 hp.  The alternator is a Leece Neville 160 amp.  We upgraded the regulator, thinking this was the cause of the problem..   After driving for a while, the voltmeter starts to climb to 16 volts, and this voltage is also registered on the Silverleaf.  The voltage drops to 14 volts, but soon climbs to 16 volts again. Rough roads seem to lower the voltage somewhat. The fault red light and buzzer on the Prosine Inverter come on when the voltage rises to 16 volts. Idling the engine drops the voltage to 13.8.  I would welcome any suggestions.  Thanks,  Jeremy

[Roy Mueller]

Check all your battery connections.  Also check battery isolator.  Also, if you posted your name or phone # I could call you.   Roy Mueller  573 220 1216

[Jeremy Parrett]

Thank you for your suggestions Roy.  I will let you know if the battery grounds or the isolator are the problem.  The main battery ground post on the chassis is right behind the battery tray.....should be fun trying to reach in there! I think there is a ground on the cylinder head as well.
 Jeremy 626 264 0576.

[Gil_Johnson]

Sounds like a bad battery.  A battery with too much internal resistance will increase the voltage demands out of the alternator.  If you have wet cells check their specific gravity.

[Joel Ashley]

The fact that the voltage changes on rough roads would indicate to me a connection or corrosion issue somewhere and the first place to look, which you indicate you're going to do as per Roy's suggestion.  Since you said you switched alternators to try and solve the problem, the alternator connections are the least likely culprit, and I'd check, clean and paint all post and chassis grounds first.  A slight film of dielectric grease on battery posts before clamping the wires on will help resist future corrosion - just don't leave any on the outside of the connection where dirt will stick to it, and where it won't let anti-corrosion paint stick.

-Joel

[Tim Bentley Co-Admin]

You might also consider the alternator.  I had the same problem that was solved with an alternator replacement.  It may be possible to clean the pick up brushes and solve the problem.  If you find this is the problem be sure to have the old alternator rebuilt and carry it as a spare.  At 120000 miles I am on my third one.

[Joel Ashley]

Sorry, I misread your post - you switched out your regulator, not the alternator.  That being the case, of course you do want to check your alternator connections, and as Tim suggested, dirty or faulty brushes, even a broken spring, could be the culprit.  Make sure all other possibilities are explored first before replacing an expensive alternator, even though carrying an old one as a spare, as Tim proffered, would be an advisable result.

-Joel

[Jeremy Parrett]

Hi, thanks for all the advice.  When I switched the regulator, I did change the brushes.  Aside from the slip rings, there isn't much else could be wrong. So, I  am almost sure the problem is a bad ground connection.
That is what I am chasing down right now.  Jeremy

[Edward Buker]

Jeremy,

I had a similar problem and also replaced the regulator. I still had voltage regulation issues. It turned out to be a 14 GA. ground wire from the alternator regulator to the engine frame had broken strands except for a couple of remaining strands within the crimp lug connector. It was not obvious. The regulator needs voltage references that are a constant without any voltage drops. It sounds like your voltage references are changing. This info is from the Leece Neville maintenance manual. It discusses sources of overcharge which would be the same problem as your over voltage condition.  

Charging system malfunction is identified by battery condition:
1. Overcharged Batteries caused by one or a combination of the following:
A. Defective battery.
B. Defective or improperly adjusted regulator.
C. Poor sensing lead contact to regulator or rectifier assembly.

More Info:
http://www.prestolite.com/literature/tech/alts/MaintenanceInstructions2500JB.pdf

Hope this helps ...Later Ed

[Jeremy Parrett]

Thanks Ed.
As we checked the alternator after installing the upgrade regulator with new springs and brushes I am sure the problem is a bad ground.   Jeremy

[Joel Ashley]

Now that you've peaked our interest, be sure and let us know the outcome, Jeremy.

[Jeremy Parrett]

When I replaced the regulator in Canada in September, I did not disconnect the ground connection at the chassis battery.  When replacing the regulator I effectively compromised  the new one.  The tech, who eventually installed my replacement alternator complete with new regulator in Pensacola this month, mentioned this after showing me how to disconnect this large cable at the chassis batteries. He also cleaned and checked the engine ground connector mid block on the passenger side, which then runs to the ground stud on the starter and on to the chassis.  The dash voltmeter still fluctuates a bit at idle but steadies up at 1500 rpm.  When I have the time and ability (back is sore), I intend to clean all these connections and weather proof them with a marine sealant. As a caveat, the cruise control which sometimes did not engage, now works perfectly. Thanks for all the advise and suggestions.  Jeremy

Marquis Amethyst 2000 C12 en route San Diego and Cabo San Lucas for the winter. http://www.bajawinters.com./index.html

[Jerry Carr]

Hi Jeremy,
I hope you have the problem fixed by now, I had a problem last summer when I pulled into Harrisburg for the rally I found the main ground cable had fallen out of the connector, seems that the folks at the factory had never swaged the connection in our 06 rig it took 3 years for the cable to actually fall out.

Hope you have a Merry Christmas and great travels in the New Year

[Jeremy Parrett]

Hi Jerry and Chris,
   I can quite believe that.  Job break for lunch maybe...... forgot where he finished and left the crimping!!!
  Bad quality control.     With coaches of this quality and complexity there are bound to be items like this.  I owned a quality sailboat built in Canada. The engine room exhaust blower worked fine...problem was it didnt blow any exhaust out. I finally discovered the problem after removing the actual blower from the cockpit underside box. The hole it would exhaust through has not been cut !!! it was screwed to the blank wall of the exhaust box !!!!!   Que sera sera !!!!   I will be checking every battery lead now for the crimp tightness and will ultimately replace all the battery cables  .    Thanks for the message.   jeremy

[Jeremy Parrett]

July 27th. 2011.
 After returning to  Florida from Cabo San Lucas we found the house batteries were very low on water. I topped them up. Now we are in Clayton NY and we have the same problem.
We also have very low cranking amps from one chassis battery. Interstate tested the battery today and found a dead cell. Could this have been our problem all along??  If so should Interstate be responsible for one alternator and six boiled 6 volt batteries?