Howdy I picked up a 1977 Titan with a dodge frame 440 power plant. Onan Genset .now to the point why would this have two voltage regulators? I've been in and out of  the automotive industry since 1978, just out of high school.
 I've replaced the head lamp switch the turn signal switch and I'm working on the tail lamp, markers and front turn
signal wiring. all were very carroded. also this unit was Gutted I can build most anything given time but man why wont this thing keep a charge. it's got a two wire field alt dodge type. dash + - gage will read nothing some times and some times will read charging should I wait to dignosis this problem until wiring finished or what??
 
Also generator wont run past choke shut down 15 may be 30 sec after starting?

please help with either question

hello. to help maybe with the 1st problem, you need a good multi-meter, first test alternator output, load the electrical system and check that the voltage stays between 13 and 15 volts, 14.5 ideal. then with everything off, measure for parisitic draw. check that the coach electrical is not with the chassis system, check for full isolation, there is a ford style solenoid for starting assist, if wired wrong or diffective will cause excess draw. also the alternator itself can cause the draw, if the regulator does not switch off, you probly should have no more than 20milliamps draw, radio memory, clock, with draw that, the dash gauge is just an ampmeter. on the generator check for proper oil level, there a cut off switch, but i suspect your carburator is full of mud and varnish, and will need removing cleaning and rebuilding good luck and have fun.

Thank You.
Should I isolate all coach systems to one battery and then use the other as if wired for any other vehical
chassie ground if so should the genorator be wired the same way  or shoulr I not use a chassie ground and use individual ground back to the battary
 
 At this point I can rewire every thing yes it does have the ford style silinoid how should this be wired to charge the coach battery

I believe the answer is yes, all the "house" electrical should be wired completely separately from the chassis electrical, though you may see a special circuit containing an isolator to enable one power source to charge multiple batteries while preventing one system from draining the batteris in the other system.

Motorhomes all have two DC systems (actually 3 if you count the 120v AC system for plugging household appliances and such into). One is engine/chassis. The other is house/auxiliary. The electrical needs of each are different, so they use different batteries. Engine system uses an automotive type battery that is designed for the brief heavy electrical needs of the starting system. These batteries however can't handle the deep discharge that usually occurs with house electric. Having a regular automotive-type lead-acid battery go dead even just once usually damages the battery, shortening it's life (sometimes drastically). For the "house", what's used are "deep-cycle" batteries (usually at least two full-size batteries, sometimes more especially if the vehicle is a luxury model). These batteries are designed for relatively low power outlet that goes on a long time (such as an electric light being on for many hours a day), and can handle a deep discharge without damage.

Chassis ground is engine battery ground. so the engine battery ground connects directly to the motorhome chassis. I do not know if the house ground is separate from the engine ground or not. Someone else needs to answer that question. I *think* it is separate, to keep the batteries isolated from each other.

The three electrical systems (house DC, engine DC and house AC) probably have very limited interconnections. For example most motorhomes have a converter (converts from 120v AC to 12v DC) that lets you charge all the batteries of both DC systems when you motorhome is plugged into an external AC outlet (such as at a campground). The engine alternator probably is wired in a way that allows it to recharge the house batteries as well as the engine battery. The Onan generator also probably has connections to both the engine and house batteries (though it might just be to the house batteries). There is also often an inverter that allows the house batteries to power the AC electrical system. The three systems are otherwise kept completely isolated from each other. All of these interconnections are designed to allow current to flow in only one direction so batteries don't get drained accidentally and problems in one system don't result in problems in the others.

If it won't keep a charge, there's basically four possible causes. 1) bad alternator (voltage regulator/diodes). 2) bad battery, not keeping a charge. 3) something is using up electricity--a short circuit somewhere or something is turned on that shouldn't be (or an electrical component is broken and drawing current). 4) you have corrosion or a poor/bad/broken connection somewhere. This stuff is tracked down using a voltmeter to check things like voltage drop and continuity (there are cheap and even DIY continuity testers you can purchase), and an ammeter to check for current drain. Corroded wires can cause excessive voltage drop and can interfere with recharging the batteries.

This stuff should be tracked down with a continuity tester and/or voltmeter. You have to isolate the bad circuit/component.

Hope this helps. I've just fixed a very similar problem in my own 30-year-old motorhome.