Generator question

[Mick9064]

I have a sunseeker 2300. I turned off the master switch for the house batteries to put it away for the winter. While checking around to my dismay the generator started when I pushed the start button. Does the generator work off the truck battery? I was always under the assumption when boondocking I run it for an hour every day to recharge the house batteries. I guess I have been lucky that the truck battery would still start the motorhome.
Mick

[2doghome]

follow up to 2/16/13 post. Finally tested the house batteries and they needed replacement. installed new batteries and it resolved the gen start issues, gen turns over much faster with the new batteries and fires right up.

[2doghome]

I have been having a similar low power start issue, with my onan generator, not sure how it is wired or where to start. When I tried to start, after sitting, connected to shore power for a month, the generator would turn over slowly, and with each revolution, the low voltage alarm on the lp gas leak detector would chirp, and the gen would not start. I connected an external battery charger to the house batteries for a few hours, and then the gen fired right off. The next day we headed out on a trip, and tried to start the gen with the vehicle running, and got the same slow turn over with chirp. We parked for the night with shore power, and while connected to shore power, it fired right off. Not sure what is going on. One time the shore power gave enough charge to the house batteries to start, one time it did not, and while under road conditions, house batteries not able to start generator from the vehicle generator charge, and there is that chirp 🙂
The coach battery is charging and the vehicle has power and no trouble starting.
Don't know if the coach batteries are getting bad, there is a connection problem, or the on board charger is not working correctly?

[Normk]

Best to start a new thread as this is a different subject. I'm sure that some of us will chime in there to help.

[Brandonrogers95]

I have an onan marquis 7000 generator. I am not getting any spark from the plugs. I have replaced the plugs, condenser, and the coils. Still no spark when I crank it. I'm all out of ideas... What could it be?

[ksg5000]

Never heard of a generator considered as a parasitic source which would deplete your battery (mine doesn't) when it's stored - should be no big deal.

[tatest]

Ask Forest River. Your generator could be starting from house batteries, not wired through the cutoff. Some manufacturers bypass the cutoff with one or more 12V circuits, which ones will vary with manufacturer and maybe model line and options.

[Flyfisherman128]

The starting battery could be the coach battery and still charge the house batteries. One thing has nothing to do with the other. My genny starts with the house batteries. I have been in the situation that there isnt enough house battery to start the genny. I'm thinking of switching mine to your setup. Oh I have a Trick l start setup to charge the coach.

[Bordercollie]

I found out that many brands and models of motorhomes have no provision for charging the starting battery unless the engine is running, i.e. when plugged into "shore power" with engine off, as in storage, the startng battery slowly self-discharges and parasitic devices also draw starting battery down. Most motorhomes have an emergency start switch which puts house and starting batteries in parallel to help start the engine when starting battery is low.

[Normk]

We've talked about his before as there are various strategies regarding starting power for on-board generators. Someone corrected my statement regarding the majority useage which was appreciated as my experience was different.

We used to see three systems for on-board generator starting:
1) Generator starting power from the chassis (engine battery).

2) Generator starting power from the house batteries.

3) Generator starting power from a dedicated generator battery.

IME & IMO, everyone should know how their own unit is arranged. Make notes in your on-board documentation as this can save time and money if problems are encountered. You will be better prepared to troubleshoot or seek help in doing so, and informing a tech ahead of time can save labor.

In addition, and once you have determined how your generator's starting power is routed, check to see whether your generator has a dedicated battery charging circuit. Some generators depend on the output to the converter to recharge the starting battery which means that the battery used to provide generator starting needs to be the same one powered by the converter. In RV applications, this would mean that the house batteries should be the starting ones.

If this is not the case, and the chassis (engine battery) provides the generator starting power, the chassis battery is not being recharged unless the engine is running. Not noticeable if engine is being used reasonably frequently but can drain the engine battery if the rig is parked for some time and generator starting drains the engine battery.

Most of the generators we used to encounter had a small "12 volt" charging output directly to the starting battery terminals which meant that the generator's starting battery was recharged by the generator's own "12 volt" output regardless of what else the generator might be powering. This is the best system but better still if the chassis (engine) battery is the generator starting one as it will not be cycled down by house loads.


Clip a voltmeter to the house batteries and to the chassis battery while the generator is running and converter turned off to determine whether the generator has a battery charging capability and where it is connected.

We changed over a run of service trucks which were not using the generator's own circuit to charge its starting battery so the batteries went dead over time. Can't imagine what they were thinking when wiring those systems....

All these things are nice to know about your own rig prior to working out a problem on which the wiring strategy may bear.

HIH

[Sidney911]

Anything is possible. The genny could be wired directly to the house batteries, by-passing the cut off switch. Or it could be wired directly to the chassi battery.

Take the cables off the house batteries and see if it starts. If it does, then the genny is wired to the chassis battery. And vice-versa.

Sid