Onan Generator Starting

[Navsafe]

I own a 2012 Tiffin Allegro RED and this has been developing over time. My ONAN Diesel Generator is a slow starter. I have serviced generator including fuel filter but I suspect my problem is electrical. The generator starts good when Engine is running (no shore power) but very slow or not at all on its own. There are two chassis batteries installed and I know the coach engine uses both. Is it possible that one chassis battery is weak? Thanks for your suggestions.

[okcnewbie]

Definately sounds like a current/cable/battery problem.

If the genset starts with the engine running it's not a generator problem IMO.

Is there anyway it using the house batteries normally and they are low?

[Navsafe]

okcnewbie,
Thanks for the reply. I originally thought it may be the house batteries but I replaced them with no change in Generator starting. In fact the the problem is worse. If it were the chassis batteries the engine would crank hard but that is not the case. I was wondering if there is a relay involved between engine starter and generator starting engagement?

[okcnewbie]

My guess would be that there is a solenoid involved to connect the chassis batteries when you hold down the boost switch.
So what could be happening is; The house battery are a little low and with the engine on it senses that and sends the alternator current to the house battteries. This helps start the genset.

How do you monitor your house batteries?
Can you get a cheap Multimeter if you don't have one and verify the voltage at the genset? Compare this to the house and chassis batteries and this should tell you which batteries are used for sure.

[rgwarren718]

I just ran into something similar on my 2012 Phateon.

I must have left something on when I left it two weeks ago because when I returned yesterday nothing electrical would work. Checked the house batteries (group of 6) and they were showing about 9 volts. Tried starting the generator and nothing but a pathetic grunt. When I started the engine it kicked over right away. Drove the coach for about 50 miles and that put enough into the coach batteries to start the generator.

Bottom line is the on the Phateon the generator starts from the house batteries. There is a crossover switch to tie all batteries together but when I tried it still was not enough to start the generator.

[MisterT]

yes, ours also is started by the HOUSE batteries, which may not seem to make sense since it is an ENGINE, and you might assume that it means that it would use the engine 'chassis' batteries, right!? but I think there are some good reasons why it does not...

- the Chassis batteries are for firing up the coach ENGINE, to get you moved from one location to another, or to the shop for repairs, or even to help CHARGE THE HOUSE BATTERIES with the engine alternator. Having said that, the generator starting with the house batteries becomes more clear. Your risk of the generator trying to start, and running down the chassis batteries, would be a risk that you could then not be able to start your Coach engine... so...

manufacturers of RVs realize that the line of risk dictates how each item utilizes what set of batteries, at least for cranking capacity concerns go.
1- the Chassis batteries are for starting the ENGINE alone.
2- the House batteries are for starting the Generator, and for the use of DC items, running in/out slides, and the INVERTER for AC items, etc.
3- the 'Aux Start' or emergency battery connect button, is for bridging the power of the Chassis batteries to help the House batteries, if low, to start the Generator.

...so the risk of the generator, DC usage, or Inverter draw on the house batteries will not inadvertantly deplete the Chassis batteries so that you always have the ability to crank your coach engine.

[lotsoftoys]

Definitely sounds like a house battery and/or connections issue. Check your voltage at your house batteries and make sure all connections between them and the battery terminals on the back of the generator are clean and tight. Minimum voltage at the battery terminals on the back of the generator should be 9 volts when the generator is cranking.

[Navsafe]

I think I have narrowed it down to a drain on house batteries during storage. The light bulb turned on when I realized the House batteries start the generator. I replaced the house batteries when this all started, I will check the voltage on the next start but I believe my problem is a house battery drain during storage. Thanks for the inputs.

[ernieh]

I had numerous starting/running/shut down issues with the generator on my 2012 Phaeton. Multiple trips to the shop failed to resolve the issue. I finally traced the problem to a ground bolt within the generator housing. The bolt has around 8 wires connected and it wasn't even finger tight.

The bolt is located just in front of the starter and requires removal of the top, rear and left side panels to access. This is not easy if your generator is not on a slide. Fortunately, mine is but your RED isn't.