| Rear Battery Solenoid [message #90379] |
Mon, 28 June 2010 23:31  |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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My 75 Palm Beach has two 6 volt batteries in the rear generator compartment, and there is a solenoid that connects the house 12 volt system to the engine 12 volt system (controlled by an orange wire). There is also a circuit breaker in the system, which protects the circuits. As there is also the front solenoid that connects the system together, is the rear one redundant or necessary? I cannot find this solenoid on my wiring diagrams.
Any advice? Can I safely remove this rear solenoid? What is it's purpose?
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: Rear Battery Solenoid [message #90380 is a reply to message #90379] |
Mon, 28 June 2010 23:59  |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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| Quote: |
......There is also a circuit breaker in the system, which protects the circuits. As there is also the front solenoid that connects the system together, is the rear one redundant or necessary? I cannot find this solenoid on my wiring diagrams.
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George, the rear solenoid is there to by-pass the circuit breaker when you activate the boost switch. You want the circuit protected so in case of a short you would not burn down the coach. Without the solenoid you would blow the circuit breaker when you use the boost because the starter would pull too much juice. I haven't looked at the diagrams recently but, if you are looking at one that is dated for your coach I'm sure it's there. Only the later coaches were wired this way.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: Rear Battery Solenoid [message #90381 is a reply to message #90379] |
Mon, 28 June 2010 23:59 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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It jumps out the circuit breaker when the boost switch is used. Without it the boost function will not work.
Keep it installed.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Rear Battery Solenoid [message #90383 is a reply to message #90379] |
Tue, 29 June 2010 00:11 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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| GeorgeRud wrote on Mon, 28 June 2010 21:31 |
My 75 Palm Beach has two 6 volt batteries in the rear generator compartment, and there is a solenoid that connects the house 12 volt system to the engine 12 volt system (controlled by an orange wire). There is also a circuit breaker in the system, which protects the circuits. As there is also the front solenoid that connects the system together, is the rear one redundant or necessary? I cannot find this solenoid on my wiring diagrams.
Any advice? Can I safely remove this rear solenoid? What is it's purpose?
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The circuit from the rear batteries is protected by the 60 amp circuit breaker in the rear. The solenoid bypasses the circuit breaker when you operate the boost switch, and essentially allows all the capacity of the rear batteries to boost the starter. When the boost is on, there is no fuse or c/b protection for the large wire from front to back, but when it is off, the 60 amp c/b protects the wire. The front solenoid isolates the front batteries until the boost switch is activated. The charge current in the front to charge the rear batteries is supplied to the large wire via the isolator (or combiner if you have changed the system).
I would not ever remove the original system, it is a very good one for protection of that very long, heavy cable from front to back. As I recall, some coaches have had insulation issues on that wire and by limiting it to 60 amps most of the time, it is much safer. With the boost circuit activated, you have the full capacity for short time periods only, not all the time. Without it, the full capacity of the rear batteries, with no protection at all would be on the large front to back wire. Not good in normal situations, worse in an accident or insulation failure.
It took me a while to figure out why GMC did it the way they did, but once I understood it, It made a lot of sense.
Rob Allen
former owner of '76 x-PB
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