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Old 10-05-2022, 09:32 PM   #1
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Tiffin Owners Club
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Separate Starting Battery for Generator

Can one install a starting battery for the Onan generator? It seems that the cranking power required for starting the generator puts a huge draw on the house batteries which are deep cycle not high cranking power.

Last night my AGS could not start the generator when the voltage dropped to 12 volts so my furnace shut down.
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Old 10-05-2022, 09:43 PM   #2
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You could install a separate battery ; but you have to remember the gen set produces no 12 volt output only 120 volt so any battery would have to be charged by other charging systems in the coach ( inverter or alternator ).

Other members say to set AGS at 12.4 volts .

Have you load tested all the batteries in the coach battery bank.

Remember the " boost " button works both ways .
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Old 10-05-2022, 10:19 PM   #3
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I have our AGS set at 12.2v. Not had an issue with it starting. I'd look at your parameter settings in the AGS & inverter/charger. It should start it. Putting on a separate battery is just a workaround to your problem.
2014 Tiffin Allegro Bus 37AP
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Old 10-08-2022, 03:52 PM   #4
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Separate generator starting batteries have been installed by many, including myself. Makes me feel much more comfortable leaving my pets in hot weather.
2019 Phaeton 37BH
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Old 10-09-2022, 12:27 PM   #5
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What CCA would I need for a 10Kw generator?
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Old 10-09-2022, 12:36 PM   #6
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Originally Posted by RandomDV8 View Post

Last night my AGS could not start the generator when the voltage dropped to 12 volts so my furnace shut down.
I did some minor wiring changes on my coach so that the gen gets cranked from the starting bank.

Makes AGS much more functional !
Ben & Sharon
2008 43' Holiday Rambler Scepter PDQ
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Old 10-09-2022, 01:43 PM   #7
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This topic also discussed here
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Old 10-12-2022, 06:55 AM   #8
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I too installed a separate battery and a Trik-L-Start to charge it. Did all of this after checking all connections and grounding. Since the AGS does not energize the Boost/charging solenoid, I lacked confidence in the system to start while we were away. Plus the White-Rogers boost/charge solenoids are failure prone.

Like the idea of hooking it to the start batteries & if it can easily done, sounds like a great option.
Walter & Loretta
2011 Tiffin Allegro Bus 40 QXP
2013 Cadillac SRX
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battery, generator

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