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dalefox · 04-27-2009, 05:48 PM

This is an interesting conundrum. When my generator is running, my house battery is being charged. But my chassis battery is getting drained at the same time. Eventually, the generator will stop running because there is no power left in the chassis battery to run the ignition on the generator. The only way to charge both batteries is with the engine running so the alternator is juicing both of them at once.

This raises a couple questions:

Is the generator supposed to charge both house and chassis batteries?
Is the ignition and starting circuit for the generator supposed to run off the chassis battery?

I have a Trimec battery monitor installed so I can see what's going on with my internal battery systems. Both batteries are new, high quality and take a charge very well. Oh, and it's a Classic 280 Motorhome.

Curious what you guys think is going on here...

Best,

Dale

bibbs · 04-27-2009, 06:59 PM

your generator has a separate alternator,to charge the 12V starting circuit.The 120V generator does not charge the chassis batery.[12V starting source] Must be something wrong with the alternator on the generator.

Bibbs

dalefox · 04-27-2009, 07:10 PM

Bibbs, are you sure? I have the Onan manual and there's no mention of an alternator anywhere on the generator. It would seem to be illogical to integrate an alternator into the design when the generator is already designed to be hooked up to the Univolt which essentially does the same thing--creates 12VDC current.

TBRich · 04-27-2009, 08:30 PM

Dale...as an aside...we're curious as to where that great photo was taken? Sure looks like Texas Canyon at the Triangle T Ranch in the Dragoon Mts along I-10 in SE AZ... or may City of Rocks State Park in NM?

OB Bambi · 04-27-2009, 08:41 PM

Dale: I want to comment on the photo, too. It is pretty but the Golden is the best part. WHAT A BEAUTY!

Randy

dalefox · 04-27-2009, 09:28 PM

Thanks, guys!

That was shot in Joshua Tree, here in California. Some of the most stunning terrain around, as well as a very sacred place. The golden beauty is my 10yr old Indigo. My boy, my pride, my best friend.

Man, Airstream and Dog. Never has a better trilogy been forged!

D

dalefox · 04-27-2009, 09:30 PM

BTW, here's another great image from that same trip. Enjoy!

/d

ROBERTSUNRUS · 04-27-2009, 11:16 PM

Hi, my Mac Tools truck, new in 1986, had an Onan generator and if I remember correctly the generator had a separate, but internal coil that made approximately 12 volts to recharge the chassis battery. [the chassis battery was used to start the generator] And I had a converter in the truck that used 110 volts, from the generator, to make 12 volts for chargeing the house batteries. I think yours should work the same.

bibbs · 04-28-2009, 07:45 PM

Dale, Rob got it right. The univolt will not charge the chassis, battery only the house battery. I still think there is a problem with the generator engine's 12V charging system.

Bibbs

dalefox · 04-28-2009, 11:22 PM

Thanks, guys. I'll look into it and let you know what I find...

Howard Lefkowitz · 05-01-2009, 09:54 AM

If you are using the original charging system then the engine battery is not being charged. As I recall none of the Classic units provided this charge capability. The generator provides the 110 A/C to your charger just as if it was using land-line power. None of the original charging systems where set up to charge the engine battery. When the engine is running then both batteries are charged. I changed the Charging system in my Classic to a Xantrex marine unit. This charger had three independent circuits so it could provide the proper charging rate for each of three battery systems in a boat. I used two of the channels and so always had fully charged batteries under any power supply situation. This worked quite well during winter storage by providing the optimum computerized charging rate for each battery system. You are correct that there is no alternator in the generator. Also, you cannot get a proper charge for both the engine and house batteries if you simply connect them together. The Aux momentary start switch, which connects the two battery systems together, is fine for starter help but will not serve to charge both batteries. The newer Motor Homes, which have large inverter/charger systems, can have Intelletec electronics that does provide the ability to correctly charge both batteries systems from any power source.
You can easily check your rig by starting the RV and then turning off the eingine and turning on lots of lights. This will take the surface charge off the batteries. Plug in to A/C or start your generator and check the voltage on each battery bank. If it is over 13 volts on each one then both are being charged.

dalefox · 05-01-2009, 05:01 PM

Thanks, Howard. That echoes my experience so far as well. The big catch is that by running the generator, one is actually draining the chassis battery. So in essence, there's a time limit to how long you can boondock without starting up the engine to recharge the chassis battery every few hours of genny usage. Right?

bibbs · 05-01-2009, 07:57 PM

No I never saw an electric starting engine, that didnt have a recharging circuit for its starting battery. They have a maginito system,to make electric for spark,and to recharge. But I havent seen everything. [yet]

garry · 05-01-2009, 08:01 PM

The generator starts from the house battery and recharges the house battery by way of the converter and only charges the house battery.

The alternator will charge both batteries (house and chassis) when driving down the road they are connected through a delay circuit and solenoid.

There is also a switch on the dash that lets you use the generator(house) battery to boost the chassis battery for starting if the chassis battery should run down this also connects the two batteries together but it is through a different solenoid.

The solenoids are the only way the two batteries could get tied together so I suspect you may have a problem with one or both of the solenoids.

I would also check for a bad ground on the house battery side.

Garry

dalefox · 05-01-2009, 08:43 PM

So it seems the only issue is a wiring problem (PO totally hacked this girl up before I got to her) so that the Gen is starting off the Chassis battery and not the House battery. Right? Because if it starts off the house battery and charges the house battery, everything is great.

So to clarify, is the Generator supposed to start off the house battery or off the chassis battery? Votes?

bkahler · 05-03-2009, 07:34 PM

Dale,

You are partially correct. However just about all generators have secondary AC taps that provide 12 to 18 volts AC (can't remember the exact number) that goes through a rectifier which converts it to 12 to 15 vdc. This 12 to 15 vdc is then used to charge whatever battery that was used to start the generator.

If you have a Kohler generator like the 7cm21-rv installed in our 310, the generator provides 7 amps at 12 vdc to charge the battery.

It sounds to me like you are having a problem with your generator battery charging circuit and should have it looked at.

Brad

ScrapIrony-2 · 05-04-2009, 12:50 AM

The generator battery IS the chassis battery...Turn the chassis disconnect switch off(located behind the rear barrel chair, on the wall), and there will be NO power to the generator starter OR the motor starter...have replaced both solenoids at one time to rectify a starting problem...when the chassis battery was low and I used the glovebox switch to 'boost it' to start the engine, it worked...BUT, when I tried to start the gen right afterwards, the engine died...I made a set of short(18") jumper cables to cross the batteries in the drawer(house to chassis), and more than once have used them to fire up the generator, so I could plug in the portable battery charger in the outside outlet to hook up to the chassis battery to achieve a responding charge...side-of the-road mental lightbulb, but it works...someday, I may even learn WHY this works, but in the meantime...it works.
m

TBRich · 05-04-2009, 09:50 PM

Quote:

Originally Posted by dalefox

BTW, here's another great image from that same trip. Enjoy!

/d

Thanks for the info, Dale...Joshua Tree is on our"Must Do" list, so we'll get there eventually...

Hopefully sooner rather than later!

Happy Trails to you and your Pup...

dljosephson · 05-14-2009, 06:14 PM

Quote:

Originally Posted by dalefox

So it seems the only issue is a wiring problem (PO totally hacked this girl up before I got to her) so that the Gen is starting off the Chassis battery and not the House battery. Right? Because if it starts off the house battery and charges the house battery, everything is great.

So to clarify, is the Generator supposed to start off the house battery or off the chassis battery? Votes?

I think you have it nailed with the PO hack idea, but they probably hacked the generator too, not just the wiring. My 1983 310 diesel has an Onan NH generator, which has a trickle charger for the battery circuit. See the schematic diagram in the service manual, there is a low voltage output from the field winding going through a current limiting resistor and diode that charges whatever battery the generator is connected to. The book says it's supposed to provide 1 to 1.5 amps of charging current. Is yours an NH model or which?