Generator will not turn over, battery problem?

[DAKC]

2019 Coachman Galleria 24T: When I press the start button on the Firefly for the generator, I get a clunk sound and the indicated battery charge goes from about 14.4v to 10.2v immediately. For another attempt, I tried with shore power connected, same result. Another time I started the Sprinter and let it run for 10 minutes, and while running I then tried to start the generator, same result. The start was for the monthly run which has worked fine in the past. Backing up to the very first try, I had forgot to turn on the propane switch when I first tried the startup and the generator turned over but of course would not start. When I tried again, the above happened. I had let the house batteries charge overnight before I tried again. Later, I turned off the shore power to check the battery charge indicator. It read 14.4v. I then put a load on the battery by turning all of the lights on. The lights started flickering as well as the Firefly panel and the battery indicator dropped to about 10.4v immediately. I am not sure where to go from here.

 

[Buly]

How old are the batteries? Looks like they collapse under load. A starter needs 12V at the starter while cranking. You may have just one bad battery that drags down the rest. Check if one is hotter to the touch after charging. Then load test each one separately. What type batteries and how old? If they are too old, you may need replacement?

 

[DAKC]

How old are the batteries? Looks like they collapse under load. A starter needs 12V at the starter while cranking. You may have just one bad battery that drags down the rest. Check if one is hotter to the touch after charging. Then load test each one separately. What type batteries and how old? If they are too old, you may need replacement?

Thanks for the reply! It's the AGM house battery which is located under the undercarriage in a box and very inaccessable. It's a 2019 so the house battery should be less than 3 years old. Same with the generator. It's located underneath and difficult to access unless you are very flexible. I checked with Coachmen tech support and they told me to check the battery connections. Good luck getting to those underneath the unit. Dan

 

[DAKC]

Update, Wednesday, 2Feb22. I just went to check on the RV at the storage facility which is covered and has shore power. It has been there for 3 days since we got back from a trip. I decided to try and start the generator again (after disconnecting from shore power) and it actually started right up! But alas everything shut down after 2 minutes and the house battery indicator on the Firefly panel went into the red and the CO/propane monitor started to beep a low battery warning. Apparently the AGM battery got enough charge after 3 days to start the generator. I can’t believe the battery would go bad after only about 2 1/2 years, if that is the cause.

 

[Dona40]

I've seen Battery's bad right off the shelf but a lot more expire before the warranty does. I've seen so many Optima's fail that I'm starting to wonder if they're that good of a deal. If you're worried about tipping over and/or vibration then yeah, go with AGM. I take care of 70+ collector cars and trucks so it seems like I'm always finding bad battery's.

 

[Dona40]

Also, If you don't keep them charged, they tend to sulfate and then they turn into anchors