Specifications: Motorhome - 2003 Fleetwood Expedition 34W - Cummins 5.9 ISB Generator - Onan/Cummins Quiet Diesel 7500Which battery group is best to use to start the generator? Engine batteries? House batteries?Issue #1: House batteries are used for 2000 Watt Inverter. Generator will not start when house batteries are at 10 volt cutoff to the inverter.Issue #2: House batteries are being replaced and I wonder if it would not be best to move the generator start cables to the engine batteries, OR install a separate battery for starting the Onan generator and provide a charging wire from the engine alternator?When the generator is powering the Xantrex Inverter/Charger, the house batteries would be re-charging.

JumboJet wrote:Specifications: Motorhome - 2003 Fleetwood Expedition 34W - Cummins 5.9 ISB Generator - Onan/Cummins Quiet Diesel 7500Which battery group is best to use to start the generator? Engine batteries? House batteries?Issue #1: House batteries are used for 2000 Watt Inverter. Generator will not start when house batteries are at 10 volt cutoff to the inverter.Issue #2: House batteries are being replaced and I wonder if it would not be best to move the generator start cables to the engine batteries, OR install a separate battery for starting the Onan generator and provide a charging wire from the engine alternator?When the generator is powering the Xantrex Inverter/Charger, the house batteries would be re-charging.I believe the house batteries are preferred and if they go dead your battery boost sw. can be used to start the genset. Also starting the main engine should charge the house batteries pretty quickly.

tropical36?Actually, don't you have that reversed? Doesn't the "battery boost" switch you refer to allow the "house batteries" to assist the engine starting battery when it's too weak to start the engine?Maybe I've had the wrong idea all these years.

I got stranded once with dead chassis and coach batteries ... after that I moved everything that was attached to the chassis battery to the coach battery. I also got in the habit of starting the RV before I tried to start the generator - that put all the batteries on-line and generator seemed to start quicker and didn't tax batteries as much.

I have to ask.....why do you want to rewire what Fleetwood designed. You give a lot of reasons why there could be a failure, but none of them will come to fruition if you maintain your batteries, both house and chassis, properly.About the only thing a coach of your era really needs is a battery maintainer that charges your chassis batteries while plugged in. There are three companies that make them, Xantrex, TRIK-L-START and Magnum.

Fleetwood and most others, start the generator off the house batteries. The boost switch works both ways. The house batteries and chassis batteries, should both charge off the shore power (generator), and when the engine is running. Unless you have a COMPLEETE set of 12 volt wiring plans, I would be very shy of re-wiring a MH, as you could miss something important, that could cause a fire down the line.

Onan Generator Starter Battery - Which one? | Good Sam Community

14 Replies

DSDP_Don
Explorer
Aug 05, 2015
I have to ask.....why do you want to rewire what Fleetwood designed. You give a lot of reasons why there could be a failure, but none of them will come to fruition if you maintain your batteries, both house and chassis, properly.

About the only thing a coach of your era really needs is a battery maintainer that charges your chassis batteries while plugged in. There are three companies that make them, Xantrex, TRIK-L-START and Magnum.
ksg5000
Explorer
Aug 05, 2015
I got stranded once with dead chassis and coach batteries ... after that I moved everything that was attached to the chassis battery to the coach battery. I also got in the habit of starting the RV before I tried to start the generator - that put all the batteries on-line and generator seemed to start quicker and didn't tax batteries as much.
GrampaR123
Explorer
Aug 05, 2015
tropical36?
Actually, don't you have that reversed? Doesn't the "battery boost" switch you refer to allow the "house batteries" to assist the engine starting battery when it's too weak to start the engine?
Maybe I've had the wrong idea all these years.
tropical36
Explorer
Aug 05, 2015
JumboJet wrote:
Specifications:

Motorhome - 2003 Fleetwood Expedition 34W - Cummins 5.9 ISB

Generator - Onan/Cummins Quiet Diesel 7500

Which battery group is best to use to start the generator? Engine batteries? House batteries?

Issue #1: House batteries are used for 2000 Watt Inverter. Generator will not start when house batteries are at 10 volt cutoff to the inverter.

Issue #2: House batteries are being replaced and I wonder if it would not be best to move the generator start cables to the engine batteries, OR install a separate battery for starting the Onan generator and provide a charging wire from the engine alternator?

When the generator is powering the Xantrex Inverter/Charger, the house batteries would be re-charging.

I believe the house batteries are preferred and if they go dead your battery boost sw. can be used to start the genset. Also starting the main engine should charge the house batteries pretty quickly.

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Onan Generator Starter Battery - Which one?

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