Onan Generator QD4000 Starting Issues

[Judy C]

Using my generator in afternoon and evening to run AC this last trip to Texas. Everything was fine until last noon stop before home and unit failed to start.
Checking the batt voltage and starting relay at unit has 13 vdc in but when energized voltage is pulled down to about 7.5vdc and generator alarms out. checked battery connections and put charger on batt making sure they are up to full charge. Any other ideas.

[bigb]

Originally Posted by Judy C

Using my generator in afternoon and evening to run AC this last trip to Texas. Everything was fine until last noon stop before home and unit failed to start.
Checking the batt voltage and starting relay at unit has 13 vdc in but when energized voltage is pulled down to about 7.5vdc and generator alarms out. checked battery connections and put charger on batt making sure they are up to full charge. Any other ideas.

Does your generator use the house batteries to start, and what do you have for house batteries? Age, number, size etc. Do you have a boost switch on the dash? If so, try starting the generator while someone holds the boost switch on, if it starts then you'll know the house batteries are either bad or discharged.

If the converter is on or if the engine is running you'll see the 13 plus volts from the charging but when you try to engage the starter on the gen, it takes a lot more current than the charging systems are providing so if the batteries don't have a charge the voltage will drop big time.

[Morich]

You don't mention which RV you have but the most common and easy way to assure there is power to crank the generator is to have the RV engine running when you try. It is often recommended to do this when trying high power items like cranking generator, moving slides, or jacks.
The basic point is that the chassis battery cranks the engine but when it is running there is equipment to tie the chassis 12 volt system to the coach 12V system.
This allows us to get "some" charge back into the coach batteries as we drive.
But the main thing it does for cranking the genset is it gives the best total power for the heavy lift!
If it won't crank with coach and chassis batteries as well as the alternator, there is a problem with the power cables to the generator or the starter itself!

Small assurance this should work? Think how much battery it takes to crank that big old RV engine? If it will crank, the little generator motor should be no problem to crank!

If it still doesn't want to crank. Try looking right at the connection where the cable meets the genset and make sure it is clean and tight!
There is also some chance the cable is dirty where it meets the power but we need to know which RV to sort that question.

Quite possible at the coach battery disconnect relay but that is "normal" and a guess rather than knowledge from looking!

[Judy C]

Thanks gentlemen all good things to check the unit is a Minnie Winnie 2004