| ISOLATOR? WHAT ISOLATOR? [message #131985] |
Sat, 25 June 2011 15:50  |
Michael Bozardt
Messages: 367
Registered: January 2007
Location: College Station, Texas
Karma: 1
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I did not know or recall what an Isolator did and it cost me.
The A/C mechanic did not know what it did either, and he hooked wiring up incorrectly just before we left for Patterson. Well, the alternator was not outputting to the battery so eventually the battery died and testing showed the alternator died too. Only after Patterson-two alternators and three batteries later did we get the problem solved and wired correctly in College Station Texas. If you need help in that part of Texas, this guy has worked on GMC motorhomes before at CROP's RV Service.
Anyway, for the uninformed, here is the scoop on isolators from the GMC Pacific Cruisers Club newsletter, date unknown.
"Therefore, our GMC coach needs only one battery for the engine load and one battery for the house load. These two batteries are isolated from each other by a solid state (diodes) Isolator that allows both batteries to be charged by the engine's alternator, yet provides isolation to prevent discharging both battteries while operating one load (engine or house).
The writer's preference is to have one engine battery (high cold cranking power rating) and one house battery (high reserve capacity rating). The engine battery needs to be located near the engine/starter. However, the house battery can be located upfront or in the rear of the coach near the Onan generator. The Onan starter current requirements are considerably less than the engine starter and the battery can be remotely located, provided the battery cables are of suitable size (large).
The second house battery (third battery) which was installed in many of our coaches is not desired, providing a suitable house battery is installed. A 12 volt house battery made of two 6 volt golf cart batteries (connected in series) is preferred due to it's high reserve capacity rating and due to it's rugged construction. The rugged construction provides means for many charge/discharge cycles. The writer's choice for a house battery is the Trojay battery, model T105."
This is the set up I have and I too, like it very much.
I also have found that if the coach does not start, sometimes it is due to a dirty battery terminal or a loose terminal. Check these before calling the mechanic.
Michael Bozardt at GEMRECS
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| Re: ISOLATOR? WHAT ISOLATOR? [message #131990 is a reply to message #131985] |
Sat, 25 June 2011 17:32  |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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Senior Member |
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the next option is a combiner. this also separates the 2 batteries but combines them whenever a charge source is present such as the alt. or the buzz box charger. the isolator will only allow the buzz box to charge the house battery and the alt. will only charge the engine battery. the way around this is to clip a jumper wire across the boost relay.
hope i got this right.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: ISOLATOR? WHAT ISOLATOR? [message #132034 is a reply to message #131990] |
Sat, 25 June 2011 22:27 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| fred v wrote on Sat, 25 June 2011 17:32 |
the next option is a combiner. this also separates the 2 batteries but combines them whenever a charge source is present such as the alt. or the buzz box charger. the isolator will only allow the buzz box to charge the house battery and the alt. will only charge the engine battery. the way around this is to clip a jumper wire across the boost relay.
hope i got this right.
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Almost correct except the purpose of the isolator is to allow the alternator to charge BOTH house and engine batteries.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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