hi guy`s, i have a question about my gen-set. I always thought that they should run off their own power... When i start my gen-set, it runs fine untill i take the jump cables off of the coach batteries.i know it needs a good battery for initial start-up,but after starting i thought it would run off its own power.(I know my coach batteries are dead.)I thought it should create its own power for spark.????any help would be apreciated. thanx, jim

I can't speak for your gen-set, but in a car one can remove the battery and it will run "IF" the charging system is working properly. Maybe you should check same. I am not an expert but this is a thought.

I don't know what equipment or generator you have, but I suspect that your dead coach batteries are sucking down more power than the generator can produce. A dead battery really loads a charger when first connected. Your converter probably can't supply enough power to keep the batteries at high enough voltage to power the ignition.

i should have mentioned that i have a Onan gen-set...Emerald series.

are you charging the coach batt before removing the jump cables

that is my point...i know that the coach batteries are dead...beyond charging...but i thought all you need a battery for was the electric start..once running it would provide own power/spark?????

Some generators will charge a 12 volt battery, some will not. Depends which model. My Kohler will not. Many converters are not intended to charge the batteries. They just provide 12 volts to run lights, etc. Some converters will charge the batteries, but how much depends on the model. Some will charge a good battery, but will not bring up a dead battery. What does the manufacturer's literature say about your particular converter? If you have a charger, the 110 volt output of the genset will charge the battery, but dead batteries are likely to absorb so much power that there is not enough left over to run the ignition.

Now, if the generator motor had a magneto, it would need the battery only for starting, and would run fine with a dead battery or no battery.

the literature on my converter says it WILL charge a 12v battery, without risk of overcharge, but i dont believe it...ive went through 2 sets of rv batteries in 5 yrs, with the second set dead now!!it seems to boil dry some cells...now their dead as a door nail. Im not too concerned about it because i have it plugged into shore power, but when the power goes off, it would be nice to hit the backup power. Last weekend the power went off for an hour, and i went to start the genset with the parralell switch on dash, as you mentioned earlier,... and as soon as i release the switch, it would stall out....when the electric is still on, and i use the same switch, it`ll stay running....but i dont need the genset when the electric is on!!! I dont want to buy another set of batteries, cause im not traveling that much. i have a nice place on the potomac river in west virginia that i spend all my free time. should i remove the batteries sinse their dead, or would that interfere with the circutry?

Did you consistently (monthly)check the fluid level of your batteries and top off with distilled water? If your batteries were in fact "boiling away" the electrolyte you might have an overcharge or regulation issue. If it were my coach I'd replace the two batteries and start a maintenance schedule. I personally have received 5 plus years of perfect service from two Sears Diehard deep cycle batteries for around $75 each battery. I always checked the fluids and trickle charged them after every trip. Kept cable ends and grounds clean. Never any problems.

thanks hilarly, but this thread seems to be getting off track a bit. I understand that my battery problem was caused by my neglect, and just plain laziness to check the fluid level, but my original question was why cant the genset run on its own power, after the initial startup? But as bill h mentioned, without a magneto, it wont. As far as the batteries go, maybe at the end of the season Ill replace them before pulling out of the woods to have power for the ride home. Ill try to take better care of them!!lol....However i do know ill NEVER buy another diehard!! Ive had it with them. Not just from my rv batteries, but my passenger car too... My light truck diehard battery ,(one yr. old) shorted out on one of my trips down to camp and cost me a lot of "out of pocket $$", and sears didnt want to hear it when i asked them for a pro-rated refund...I had a receit, but they tried to say the mechanic was "shadey",and sinse i didnt haul the shorted out battery with me on my trip, and return it, they wouldnt refund!! but thats another story....Im going INTERSTATE from now on!!lol ...thx everyone for your help on the genset prob.

Zurful, I am not real sure what exactly you want here, but I will assume that you are on camp power except when it fails, and only need batteries to start and run the generator. If so, here goes:

Issue #1: Yes, you can eliminate the coach batteries. You will have to connect the chassis battery to the coach system, rather like the paralleling switch. You should do it with a manual connection that will not draw power all the time, as the solenoid does. You should be able to disconnect the coach from the chassis battery when you are not using it to prevent discharge.

Issue #2: As hilarlee mentioned, you may have a problem with your converter. I would recommend buying a good quality digital voltmeter and really monitoring the voltage. I have a permenent one. Your present converter could end up wrecking your chassis battery, too. Older, less sophisticated converters need the battery in the circuit to act as a load and capacitor. Without a battery in the circuit, you could get voltage peaks and spikes, or just high voltage which could wreck your fridge circuit board (depending on the year) and so forth. Modern, solid-state converters do not need a bettery.

If you don't feel like buying a new converter, a good automatic automotive battery charger could keep the chassis battery up while you are on AC or generator.

Remember, a chassis battery does not like to be discharged very much, so if you plan on using JUST battery power for much else beside generator starting, get new coach batteries and monitor their charging.