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Old 06-24-2018, 11:51 AM   #1
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Thumbs down Which battery starts my genset?

I want to service my genset (Cummins Onan RV QG 4000) on my Forester. The instructions say to disconnect the negative battery cable at the battery. My question is which battery serves teh genset, the house battery or the truck battery? Thanks

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Old 06-24-2018, 12:18 PM   #2
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On my Solera, the house battery.

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Old 06-24-2018, 03:00 PM   #3
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or disconnect the cable on the generator.
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Old 06-24-2018, 07:02 PM   #4
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My genset always takes more than one attempt to start it. My house batteries drop in voltage when I start the genset.

This is a good idea to disconnect.... It is so easy to accidentally hit the start switch while working on the genset.
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Old 06-25-2018, 12:26 PM   #5
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Normally the generator is started using the house batteries. If you have the emergency start switch, activating it can allow the generator to be started from the vehicle battery.
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Old 06-25-2018, 12:50 PM   #6
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sask, if you are having trouble starting yours do what I do. Open the generator door and you will see 2 rods on top of the carburetor. One of them goes into a box ( I imagine for the governor) on the right. See if that rod will move to the left (front of the motor home)

I check mine before we leave and it's ready to go when needed. Prime about 10 seconds and now it starts on the first try. I have to do this whenever the generator is cold.
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Old 06-25-2018, 12:52 PM   #7
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Servicing the genset or just changing the oil? For servicing, I pull the negative cable off the house batteries. For changing the oil its a waste of time. YMMV
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Old 06-25-2018, 12:55 PM   #8
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Welcome to the forum its a great place to get your questions answered as you can see.
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Old 06-26-2018, 01:34 PM   #9
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Originally Posted by CHICKDOE View Post
or disconnect the cable on the generator.
I'd be very leary of disconnecting the neg cable at the generator. The battery connects to the chassis as does the frame of the genset. While you probably won't have a problem, it's a lot safer to disconnect at the battery.

Disconnecting the positive lead at the genset is even worse. Once disconnected, you have a "live" heavy duty positive wire that's loose and could easily come in contact with the frame, creating a dead short across the battery. Anybody want an unexpected arc welder?


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