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Topic: Dead chassis batteries (Read 1605 times) previous topic - next topic

Dead chassis batteries

Left Walla Walla on our three week trip. Got as far as the Pilot TS in Wasco. (3.5 hrs) Shut it down to fuel up and 20 minutes later. No start. Ran genset and used boost. Again nothing.

Called coach net and they dispatched a truck. It took about 20 minutes @ 60 amps to the batteries (3 yr old red top AGMs) to get it started. Service guy said the AGMs are crap in general and mine are likely toast.  MultiMeter showed them just over 12.3 V. Prior to the charger being hooked up.

We drove to The Dalles and are at a diesel truck/RV shop. What do I need to look out for? My plan is to have them isolate the batteries and do a battery test. Also do a voltage check at the isolater to asses the alternators condition.

I hope to one day have trip go reasonably well. But I suspect that is a pie in the sky request.

Re: Dead chassis batteries

Reply #1 –
Start by disconnecting the three batteries and completely isolating them so you can measure no load voltage separately. If any one is a couple of volts or more lower than the others, keep it disconnected and reconnect the remaining two. That one has shorted cell(s) and is draining the others. I got by with just two batteries connected for some time before replacing the bad one. But my U295 needs less juice to start than your U320.

And AGMs are not crap, in general nor otherwise. I got five years on the Optima that shorted, plus another six (11 total) on the other two before replacing all three. And I've been going strong on my three 8D Lifeline AGMs for four years now.

Re: Dead chassis batteries

Reply #2 –
This sounds like an intermittent start solenoid failure.  Did the dash light up when you were trying to start?  When you tried to start, did the starter spin but the engine fail to start, or did you get nothing?  Many here leave their engines running while fueling just to avoid your situation.  Their are threads you can read about how to diagnose your situation and work around a bad solenoid if necessary.  Let us know what you find.

Re: Dead chassis batteries

Reply #3 –
Sorry, Jerry, for your troubles.  Agree with Tom and Brett (above) on all counts.  Disregard Bubba's comments about AGM batteries.  Don't start replacing stuff until you pinpoint the problem.  Try the tests you propose, and any others that our members suggest.  You may find it is a relatively simple (cheap) fix.

If the voltage on your start batteries is good (see chart below), move to the ignition solenoid as the next likely "suspect".  There are many threads on the Forum about testing and replacing the ignition solenoid(s).  For instance:

Need dash solenoid I'd please

Ignition solenoid on a u320.

Suggestion for the future, prompted by my reading about similar incidents (remember Roland's extended campout at the fuel island?):

1.  Install two separate volt meters on your dash so you can monitor the voltage of both battery banks while driving.  They don't have to be fancy or expensive.  The ones that plug into the dash power outlets (lighter sockets) will do.  You want some kind of early warning of a declining voltage situation in either bank, hopefully before you shut down your engine in a inconvenient location.

LED Car Battery Electric Cigarette Lighter Voltmeter Voltage Meter Gauge...

What did you do to your coach today VI

Re: Dead chassis batteries

Reply #4 –
Quote from: bigdog –
I hope to one day have trip go reasonably well. But I suspect that is a pie in the sky request.
I'm sure you've said, many times, "WHY ME?" Knowing you pretty well, I don't think it's karma, it's the luck of the draw. It's rather trite, but I believe the great quote: "This too shall pass."  Good luck, Jerry & DW!  ^.^d

Re: Dead chassis batteries

Reply #5 –
The service man said that the starter spun the engine 'not quite one turn' So it was engaging.
Right after this he got under the coach and felt for a hot starter. It wasn't hot.
Dash was going dark after starter engagement.

Coach is usually plugged into 30amp while in storage and was on 20 for a few days at our curb for trip prep, packing.

Re: Dead chassis batteries

Reply #6 –
I would check battery connections especially the negative. Many times a loose connection creates resistance and won't let you start. Start by removing, cleaning and reinstalling connection. This doesn't cost anything and many times solves the problem.

Re: Dead chassis batteries

Reply #7 –
I checked each battery. All were at 11.7V
Upon opening the bed and looking at the selenoid. I found a broken wire that 'was' hooked up to the passenger side terminal of the selenoid. I wonder if that is the chassis batt sense wire. As it's not a heavy gauge one.

Not sure how to get a photo from my iPhone over to the forum.

Re: Dead chassis batteries

Reply #8 –
Gerry, that wire that you reckon was originally hooked up to solenoid may be the Wire that energisers the boost solenoid as any wire for sensing should come from a permanent hot source. My sense wire comes from the hot side of starter solenoid and I had the same problem 5 yrs ago with it being corroded off. Fixed that connection and all was well.
My comments too on AGMS is that ours have been good for 7yrs and no issues, would not change to any others.
JohnH

Re: Dead chassis batteries

Reply #9 –
Quote from: bigdog –
I checked each battery. All were at 11.7V

Upon opening the bed and looking at the selenoid. I found a broken wire that 'was' hooked up to the passenger side terminal of the selenoid. I wonder if that is the chassis batt sense wire.
Batteries at 11.7 volts are well below 50% discharged.  You should get a good battery charger hooked up to them ASAP.  Even if the coach is connected to shore power (is it?) the start batteries will not be charged unless the boost switch is activated (or you have some other add-on means of charging them).

So that's the next step: figure out what that broken wire under the bed is for, and fix it.  Agree with John - most likely the activation wire for boost solenoid.  Which is why, when you could not get coach started, hitting the boost switch did not help.

THEN you will need to figure out why the start batteries were not being charged while you were driving.  Even if the sense wire from the alternator was broken or disconnected, you should still be getting some charging action out of the alternator.  It may not fully charge the start battery bank, but they should certainly be staying above 11.7 volts.

Re: Dead chassis batteries

Reply #10 –
The batteries are being charged as I type. Once we get the engine started they will test the alternator. Then we will proceed from there and decide if our trip is kaput.

Re: Dead chassis batteries

Reply #11 –
Sounds like the batteries are not charging from the alternator.

Re: Dead chassis batteries

Reply #12 –
Jerry, sorry you are having problems.  They will get fixed. If not the alternator be sure to check the isolator.  They fail.  Check every connection, clean and tight, grease with conductive grease.

Re: Dead chassis batteries

Reply #13 –
No worries Roger. I've grown rather numb from the constant issues. I would be more shocked if everything went well (which I know is a horrible way to think)

Not sure where the isolator even is or what it looks like. I'll ask the tech about it should it get that far.

Re: Dead chassis batteries

Reply #14 –
Alternator is charging. MultiMeter shows 15v at the alt output lugs. Also the volt meter in the dash panel shows good as well. Yesterday it was reading 9v at the dash.
I cleaned all the individual batt posts & connectors. Tech also cleaned the connection from the battery connector bundle that goes to the systems.
Tech said that it could be an intermittent issue from the alternator (starting to go bad)

We will go on to silver falls as Salem has a number of RV shops in the area.

Re: Dead chassis batteries

Reply #15 –
Clean ground(s) where attached to frame?

Re: Dead chassis batteries

Reply #16 –
Measure the charge rate at the BATTERY. It could have problems anywhere from the alternator output to the battery connection.

Re: Dead chassis batteries

Reply #17 –
It seems odd that all the batteries had the same voltage (11.7). Did you disconnect and thus isolate each battery? If ONE battery has a bad cell I believe it will read 10.3 and it will drain the others.

Re: Dead chassis batteries

Reply #18 –
Yes. I totally removed the battery cables before measuring each individual battery.
After making the 7% climb up to Mt. Hood for a lunch break. The voltage at the batteries on high idle (850 RPM) reads 13.83v on my multimeter. And 13.7 on the old audit CRT display.

Engine temp was great on the long climb.

Re: Dead chassis batteries

Reply #19 –
Quote from: bigdog –
Yes. I totally removed the battery cables before measuring each individual battery.
After making the 7% climb up to Mt. Hood for a lunch break. The voltage at the batteries on high idle (850 RPM) reads 13.83v on my multimeter. And 13.7 on the old audit CRT display.
Then your charging system is fine.