Onan gas generator not starting

[Landsub]

RV in storage yard. I start generator and RV every month when I pay the fee. This time the generator wouldn’t start. Sounded like it is a dead battery. I checked the test lights and it showed batteries at the lowest level. I checked them with a meter and both batteries showed over 6v, and over 12 in series. I started up the RV and it started normally. Then I started the generator, which also started normally? We do not boondock so we only start the generator to run it as required. Not sure what is going on.

 

[Bigblockyeti]

What was the total battery voltage? A little bit over 12V and they're close to dead. I like to see a minimum of 12.6V on a battery (or pair of series 6V) that's been sitting for a while. They might be letting you know it's time for replacement. How old are they?

 

[Landsub]

You may have something. Battery voltage is 12.4. We bought the RV 2 years ago this sept, with these batteries. Thanx 4 the help

 

[Bigblockyeti]

Do the batteries have dates on them? 12.4V isn't awful, especially for having sat. Did the generator even try to start or did its starter motor stall against the load of spinning the engine?

 

[B52Bombardier1]

Charge up the battery overnight and then take it to be "load tested" at an auto parts store - typically, a free test. This test is more than a simple measurement of battery voltage using a multimeter. This test sees how many amps the battery can deliver into a load bank with a known amount of ohms resistance for a brief amount of time.

Volts x amps = watts = power . . . the ability to do useful work. Such as spin a starter motor. A voltage measurement by itself is only half of the equation that needs to be solved.

Rick

 

[Kevin D Pem]

I would guess that you don't run the generator long enough to bring the battery back up to full charge after the start draw down. In addition to the sensors load, this can happen quite easily.

May I suggest a solar battery maintainer.