Please help auxiliary start!

[Aarondj]

Hello my name is Aaron and I'm new to this site and unfortunately my first post is a problem post... I'm having an issue with my chassis battery and my auxiliary start, my chassis battery keeps draining for some reason I'm thinking it's probably going to or already has a dead cell in it. I was going to move my RV so I was going to utilize my auxiliary start button, which I have done a couple of times before. This time I pushed it and nothing happened I tested my house batteries and they both tested a good 12.7 with no Shoreline or generator running. I'm thinking it might be a combination of my solenoid and my chassis battery having a dead cell does this sound likely? Could this also be the cause of my generator not starting because when I try to start it it seems like it just does not get enough juice. I've already replaced the fuse to my auxiliary start in the main panel under the hood I couldn't find a secondary fuse on the solenoid line or a second solenoid so I believe there's only one solenoid. Please any suggestions or insights into this would be very helpful we've only had this RV for a little over a year and electrical problems or not fun!

[BFlinn181]

It would help us help you if you put your RV information in your signature. Go to 'Users CP' to add info to your signature.

I don't know which batteries, house or chassis, are the ones that power your boost solenoid. If that group of batteries are dead, then the boost wouldn't work. I'd suggest cleaning all battery contacts, including ground connects as a first step. If you can plug in your shore cord, even into a 15a oultet (with dogleg adaptors) your onboard converter/charger will start charging. After a few minutes of plugging in, check the voltages at each battery terminal to see if the converter/charger connects to just house batteries or also connects to chassis batteries when a charging voltage is present.

After batteries connected have had time to charge up completely, disconnect shore cord and wait a couple of hours for surface charges to be absorbed. Then take voltage readings again at the battery terminals. A good battery should read 12.7v.

If you have jumper cables, you could jump the chassis battery and start the engine, then do the voltage readings as the engine is running. If your charging system is bidirectional, you should read 13.4v or more at each battery in the chassis and house batteries. If you don't see both groups of batteries connected together when a charging voltage is present, you might have a bad battery isolation solenoid or perhaps your RV never had that capability.

[Aarondj]

Well I thought I put that in there during sign up but its a 1987 Komfort MT 31'6". I started it with a booster box and all the batteries were being charged adequately through the alternator, and it was running fine. I moved it let it run for a while then parked it back again, shut it down let it set for a while. I checked the batteries with a multimeter and the house batteries read 12.7 both, and the chassis battery read 11.3. Then tried to start it again and it wouldn't even turn over, so I tried my aux start button and again nothing. I went back out and check the batteries again the house batteries both still read 12.7, the chassis battery read about 10.8 but it still wouldn't start and it doesn't seem the auxiliary start function is working properly either I've used auxiliary start before and never had this problem. Did the chassis battery just have that bad of a cell to where it's not even activating the solenoid properly?

[BFlinn181]

10.5v translates to 0% state of charge.


I'd clean all battery connections and grounds before too much more effort or expense.

[Aarondj]

So basically if my terminals aren't loose or corroded then it is most likely my chassis battery cell is dead is that correct? Would that explain why my Onan generator won't even turn over unless the motor is running?

[BFlinn181]

You didn't mention the ground connections. These are often overlooked and can cause the symptoms your report. Using a jumper wire from the (-) post to the frame or engine block can eliminate this. Are all the voltage readings of the batteries taken directly at the battery posts?

[MSHappyCampers]

Hi Aaron! Welcome to IRV2! We're sure glad you joined the gang!

Bob is giving you good advice!

Good luck, happy trails, and God bless!

[Aarondj]

Yes they are taken from the posts with out a generator or shore line. I took the chassis battery and had it tested today it's shot now I need to look into getting a new one. Which brings on yet another question is the hundred twenty volt converter supposed to charge the house and the chassis batteries? Also any recommendations on a cost-effective starting battery because the house batteries are still fine.

[BFlinn181]

Many RVs do connect both the house and chassis batteries together when a charging voltage (+13.4V) is present, then disconnect when no charging is detected. Don't know about an '87 Komfort, but with a voltmeter you can find out. Take readings at each battery after they have had time to absorb any surface charge. Then plug in the shore cord and take readings again. (some battery isolators have a delay, so give it time) If you now read a voltage increase, you have your answer. You could then try the same test with the shore cord unplugged and the engine running to see if it's bidirectional.

[96Bounder1st]

Not sure but from past experience you can not boost thru a truly dead battery. Check your cables, connections and grounds. A bad cable as mentioned above can mirror these symptoms.

Good luck,
Terry

[Aarondj]

I like thank everybody for taking some time to read and reply and helping me figure out what's going on here I guess it's off to get a new start battery of some sort and then check all my connections. Any suggestions on a cost-effective starting battery?