In the 94 Bounder that we used to have, I am just sure that all the batteries (chassis and coach) could be charged by the alternator. I recall that there was a device (the name escapes me) that would select the lowest battery for charging. I now have a 98 Adventure also with a 454 Chevy chassis. It does not appear that the coach batteries are charged form the alternator. Is that the way it is supposed to be? I am having to charge the coach battery with the Onan unless I have shore power. Do I have a problem here?
The device is called an isolator, and it is installed between the alternator and the 2 or more sets of batteries (coach and chassis). The purpose is to prevent you from draining "both" sets of batteries if you will while you are not running the vehicle. It is essentially a diode set that prevents backward current flow. My guess is that someone either bypassed it (hooking up the original alternator output wire to the alternator) or it is defective.
You could use a voltmeter to test it, it is a rectangular box with typically 3 or 4 studs (depends on how many sets of batteries you have) on with heavy cables going to each set of batteries. If there are 3 studs, one will be the output ffrom the alternator (would measure zero volts without the engine running), one would be for the coach batteries (would measure somewhere around 12 volts without the engine running), and the last would be the chassis battery(s)and it would measure about the same as the coach batteries without the engine running.
After measuring voltages without the engine running, measure them again at all 3 places with the engine running. They should all be very close in voltage and should be greater than 13.6 as long as the alternator is "excited". You may have to raise the RPM's slightly to get it excited on some GM Alternators. If they are not the same, you most likely have an open diode and the isolator will have to be replaced.
Not all manufacturers wire the same. You are right about the Bounder. My engine alternator will charge the chassis battery first then the house batteries while the converter does the house first then the chasis. Your new rig might not be set up to do that and keep the chassis and house systems seperate.
The way I see it, niether is "more correct' that the other, just different philosophies
You may want to look at your dash area for a 3 position switch possible label dual batt. If you do center is off, 1 side dual batt. on and other side emergency start. On dual battery side on it ties chassis battery to coach batt. when ign. key is turned on. If you have 2 master disconnect switches(one for chassis batt. and one for coach} they both need to be on. If electronic isolator [it has cooling fins on it test as previous post. If mechanical solenoid you will see 2 heavy wires opposite each other on 5/16 post and small wire on little post on center terminal. The trigering is when 12vt. is applied to center post it should activate internal electromagnet and make click sound which internally locks each 5/16 post to each other. One side post is chassis and other is coach battery.
Your rv convertor from 115vac normally will not charge chassis battery.
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I have never seen a motorhome that was not wired for the alternator to charge both the chassis battery and the coach batteries. There have been a few that had some type of isolator that was manual, but none that are wired as they left the factory that do not chage all batteries when operated properly.
Good travelin! ........Kirk
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Fulltimer since April, 2000 URL:www.adventure.1tree.net
I have not found the isolator and it does not appear that the alternator is charging the coach batteries. This I checked with a meter connected to the batteries. I would like to know where the isolator is on a 1998 Adventure 32'er.......mike
Those heat sink Isolators are about as obsolete as Carters pills. Their not there anymore !
For years most all RV's (fleetwood I know) use switching relays for connecting all the batteries together when the ignition switch is turned on. And there is most times a 5 amp fuse in the actuator wire to the relay. If the house batts are not charging, either that fuse blowed, or the relay contacts are bad.
And I dare say, there ain't a Motor home alive that was not designed to charge ALL the batteries when the chassis engine is running !
Rich
Rich
' 98 Flair, 454, Onan Microlite 4k, Intel PD 9155 w/ wizard, Sta-power 1500 watt Inv, 2 6v batts, ammeters, Oly Catalytic Heat, hauling 2 Bent Bikes and sometimes towing a Tracker F&S boat.
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