DC Shutdown When Starting Generator

[tmet]

Most likely cause(s)? 2017 Sunseeker 3050S bought new. Scenario: AC shore power disconnected after being on for 2 weeks. Generator start attempted on BATTERY POWER. Struggles, barely turns starter then dies completely... like dead DC power, even though house batteries are initially fully charged (starting 13.2 volts). Kills all house DC. Start truck engine, try again, generator then starts normally and all DC is restored. Truck engine turned off. If systems, like the refrigerator, are then running on propane, once shore power is restored, it doesn’t switch back to AC immediately and the DC appliances operate on significantly reduced power, i.e. lights come on, but dimly. A short time later, full DC operation resumes, cause not determined; refrigerator switches back to electric. What components should I look at to find the cause(s). System has worked perfectly until 6 weeks ago. Time between generator 5 minute "exercise" runs normally 2 weeks, done since new.

Specific related components: Onan Q64000 Cummings 4KYFA - 26100P Generator, Progressive Dynamics PD5100 Automatic Transfer Switch and PD4500 Series Power Control Center.

Thanks in advance.

[glen1971]

First guess I've got would be the battery you are using to start the generator has an issue. Have you done a load test on it? It may have 13.2 volts, but have little to no capacity. If the generator starts when your truck engine is running, the generator itself sounds ok.

[BehindBars]

The house batteries initially struggling to start the generator is a big red flag right there. Check the quality of the battery connections. Have the batteries load tested or replace them.

The single 13.2 volt measurement doesn’t tell the whole story. What was the voltage during cranking? What was the voltage on the batteries right after the failed attempt to start the generator? What is the battery voltage when AC shore power is restored, and later when DC appliances begin working normally again?

If the batteries are not sealed, when was the last time the electrolyte level was checked?

[phillyg]

I'd also suspect battery connections are weak. Second place would be the transfer switch.

[CHICKDOE]

13.2 seems a bit high for fully charged batteries. was that the reading after being disconnected from shore power for two weeks? or was that the reading when connected to shore power. if so this is the float voltage from the converter.

everything you describe points to weak or discharged batteries.

[TitanMike]

Very first place I'd start, before any other guesses or actions, would be at the battery terminal connections. Remove each one, clean to shiny metal on connector and terminal, reconnect, move to next one.

I got an emergency call one year from my Mother. She couldn't get the generator started and lights went out. She wanted me to come and replace her batteries.

I stopped in, took one look at the batteries, then proceeded to do that I said above.

About 30 minutes later the generator fired right up. FWIW, the battery terminals didn't look all that bad as her husband (who was at the time in the hospital getting a cardioverter installed) had been doing the old "Baking Soda Bath" a couple times a year. Inside of connectors were so corroded I had to use a pocket knife to peel the corrosion off both connector and battery terminal.

It's not uncommon to read full voltage but once high current of a starter motor hits, the connection breaks.

Clean terminals will provide quicker charge times and more reliability. Start there first. They'll need to be cleaned anyway.

[BDenn]

Last year I started with grey water electrical connections found them loose and corroded. Went on to black water. Went on to all the ground wires on the chassis. I found the ground coming from generator. loose and corroded. Do not know if this is a backup ground. Just reporting what I found.