No power to generator starter

PV followers · 08-10-2021, 05:11 PM

I accidentally tried to start the generator while plugged in to shore. I have nothing from any of the 2 switches in the coach or the one on the generator to the starter. Checked the breakers and relays. Checked the fuses under hood but found nothing related there. I was told it was probably the battery cutoff switch. I tried the aux. Battery switch and nothing. Help is much appreciated.
2004 winnebago adventurer 37b

Morich · 08-10-2021, 08:42 PM

When they told you the battery cutoff thing, they did not go far enough to explain it.
This drawing may help? Click the picture to get a better view but it comes from this drawing:
https://www.winnebago.com/Files/File...ire_146761.pdf

Most motorhomes have a mode solenoid which connect the start battery and coach batteries together at different time. One is when we have a weak start battery and we want to "jump start" it we can push a "boost "switch on the dash while we crank the engine.
OR when the engine is running, this solenoid should connect them batteries together so we get a bit of charge back into the coach batteries while we drive to the next camp or home!
I drew the green and red as power from each battery and they join in the mode solenoid .

But at this mode solenoid there is a ibg battery cable going to the Battery disconnect or sometimes called "aux battery" disconnect relay, usually right beside it.
When the switch is pushed the right way the relay connects to pass the power through to the rest of the RV like lights, vents and water pump but also the generator starter! This is a relay that stays connected or disconnected (latched) in whatever position we left it when we let go of the switch. It uses power to move the really but a magnet holds it so we are not using battery full time after we let go of the switch!

The idea is that if the lights, fans, pump are working, the relay is doing what it should to get power to the generator starter! It should be headed that way but if there is a corroded or dirty cable, it may not get to the starter solenoid on the generator.

I would make sure all the rest is working, then if okay, check at the generator where you should find a big red battery cable and it should have 12+ volts on it coming from the coach batteries and through the disconnect relay.
If you don't find 12 volts on that cable, look for corroded or dirty connections along the way!

PV followers · 08-11-2021, 11:22 AM

Thank you so much for the help and explanation. I've only had a coach for a week and a half so everything is a big help. I captured this info to keep handy. I bought a battery load tester that arrived yesterday. While testing the batteries I found the ground cable for the engine battery was loose. I pulled the cables off and charged the battery. The generator started up as it had before. I really appreciate you explaining how the circuit works. Very helpful.

Morich · 08-11-2021, 01:11 PM

Bad batteries and bad connections are two of the most frequent problems we see on the forum and part of that is just due to the odd way we often use the Rv batteries.
We may tend to treat them like we do the one in our car but when we only use the RV occasionally, that doesn't work.

Two big points to keep in mind will help getting used to things. One is that batteries are really simple but really confusing when we look at voltages. We may run a charger of some type and find the battery says it is really charged at 14 volts, so we think that it really charged up high and really quick so it's a great battery!

Not TRUE! What we are seeing is the temporary effects of the chemical reaction of charging and right at the posts, not what the whole battery may be doing!
So if you get a reading higher than the natural state of a fully charged battery of about 12.8, know that your charger is working but wait a few hours to see if the battery actually stays charged after things settle.

Second point might be to know that the converter on the Rv will charge the coach battery only if you don' have some form of devise to get a connection to the start battery. And there are almost always small drains which WILL run both sets down if we don't do something to help them. Small things like radio presets on the start battery and CO and propane detectors are two on the coach that are easy to mess with our minds as we forget them.
Not hard, just confusing to get in mind at first!

deckape · 08-19-2021, 06:59 AM

Since you found one bad connection, I would go thru all of them ,remove, clean , check and coat with grease and install. Go thru all electrical connection and tight them. Power off of course.