Onan Generator Battery Not Charging

[sgrol60]

I have been boondocking with generator power twice with my TH. Both times the generator would run for several hours and then shut off. I would open gen cover and try to restart with no success and no lights, clicking, nothing. A little background: when we bought the TH the dealer agreed to install a second battery. They hooked up the neg of the new battery to the neg of the other (house) battery and neg of gen and the positive of the new battery to generator only. This last time the generator quit I measured the gen battery and found voltage to be less than 10v. I charged the battery and restarted the generator. As I was monitoring the gen battery voltage I noticed it was declining. I now understand some RV generators don't have a charging circuit like most engines that use a battery for starting. The generator powers the converter on the RV and it recharges the battery. I believe that in my case, the dealer did not correctly hook up the gen battery. I think it's positive should be connected to the house battery positive. Is this correct?

[FT4NOW]

I thought the battery was only charged by the converter and hooking the battery to the generator was to start the generator.

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[Big Mike]

Yes that positive should be hooked up to the battery to charge off of the converter. I am assuming it is an Onan genset and you are correct, there is no charging circuit (alternator) built in. At this point, you want to revisit whatever wiring that dealership did, it sounds as though there is something else going on. The “original” wiring to the generator, unless it was added aftermarket, should come right from the house battery, and then the second battery wired in to the house battery.

Big Mike

[JCR GD]

You are correct. The way it is now there is no house pos connection to second battery. Add the connection between the pos terminals and you should be good to go. Be sure wires between batts are big enough cuz you are in essence adding a second battery to your house system. It will not be just for the gen. Also, both batteries should be same ratings.

[sgrol60]

"Yes that positive should be hooked up to the battery to charge off of the converter. I am assuming it is an Onan genset and you are correct, there is no charging circuit (alternator) built in. At this point, you want to revisit whatever wiring that dealership did, it sounds as though there is something else going on. The “original” wiring to the generator, unless it was added aftermarket, should come right from the house battery, and then the second battery wired in to the house battery.

Big Mike

You must be correct. Since the TH came factory with one battery and the Onan 5500, the gen would have to have been connected to the positive of the house battery. Don't know why the dealer tech would have moved the gen pos to only the extra battery and not jumpered the two battery positives together.