Charging System Problem???

[Lee Bornstein]

Just came back from trip to Palm Springs on Sunday and noticed while my Engine was running the Voltmeter on dash was bouncing between 26 - 28 volts and dash lights were also dimming/brightening in unison with the changing voltage.

Once parked and just before shutting off engine the RED + - Battery indicator on dash was lit up .

Just started engine again (48 hrs later) and Same fluctuating voltage but battery + - light is off.

What does this mean? Problem with 24 Volt Alternator?

Lee

[dalej]

Sounds like it Lee, we had this simular problem back in 2001, while driving down the interstate the heads were pulsing and it ended up being the 24v alt. not the one on the 8v but the aux. one.

[Jon Wehrenberg]

Lee,

Your alternator or voltage regulator could be starting to fail.

I think you have the 8V92 and if I'm right check the field wire which runs from the voltage regulator to the alternator. If you have the 8V92 there have been problems in the past with the field wire at the alternator. Good luck. It is nasty under there trying to see the wire and its connection to the alternator.

If it is an alternator failure plan on letting someone else tackle that job. It is a bear changing that alternator and it can be done from under the coach.

[Lee Bornstein]

Jon:
My coach is 97 Liberty 40' - 60 series engine - 24V Alternator is next to cooling fan and belt driven from gearbox. Looks easy to access.

Only two wires (size if battery cables) attached to alternator. Where's the Regulator for this?

Just examined the belt - It has a crack and a lump in it at the point where it's cracked. Possibly it's slipping every time it hits the crack. I'll replace belt first and see if that improves situation.

Lee

[Jon Wehrenberg]

Your voltage regulator is on the forward bulkhead above the bus batteries.

If your alternator is failing at least it will be easy to change compared to the 8V92.

[Loc]

Lee

Check the voltage regulator. From my experience, don't run the bus very long with the light illuminated. Last fall my voltage regulator went out, red light came on, battery isolator caught on fire, fried a lot of the wiring, destroyed the chassis and coach batteries and caused a really nice, not to mention expensive, mess. At least I was able to put the fire out before I had a car-b-que. I replaced the alternator, voltage regulator, isolator, battery equalizers, a lot of wiring, and all chassis and coach batteries.

Good Luck,

Loc

[Lee Bornstein]

oops - Guess I was wrong. Small Delco Alternator is 12V - 145A charging system for house batteries. It has internal regulator. Replaced belt.

After thinking about it... Dash Volt/Amp meters are labeled Engine and House.

House system is 12V and Engine Alternator is the 24V - 270A BIG Mother.
Problem appears to be with the 24V System - not House System. Found regulator in engine compartment and will do some research as to how to test both Alternator and Regulator. We'll see what we can do.

[truk4u]

Lee,

Are you sure about the 12V? I thought the small alternators where for the start batteries and the 24V 270 is for house.

[Lee Bornstein]

Tom:
That was my confusion also. My Prevost Build Sheet shows 12V 145A Alternator was add on option when coach was built.

I have Prevost Bus Air and the blowers for that use HUGE 24V DC motors, engine has 24V starter, 4 - 12v engine batteries arranged in 2 banks of 24V and that's why the 270A 24V Alternator.

My coach batteries are 3 - 8D Gel Cell 12V batteries all in parallel so the 12v-145A small alternator handles charging of those while moving down the road.

Lee
97 XL 40 Liberty

[Jon Wehrenberg]

Don't ask me to explain this because I don't understand the logic, but I think I am correct.

On earlier coaches (perhaps those with 24V lights) the alternator was 12V, and charged the 12V bus batteries via the equalizer. On later model coaches, perhaps those with 12V lights, the bus alternator was 24V.

That makes sense, right?

[MangoMike]

On my 97 Liberty Classic, the house is 12v, the house alternator is 12v, 145amp. The engine batteries are charged by a 24v alternator.

Mike

[truk4u]

Thanks Lee, I surrender!:confused: Glad I only have one big fat alternator.