[Michael]

If the chassis voltmeter read only “21” going down the highway at speed, I think you are more likely to have a charging problem (alternator and/or voltage regulator) than you are to having a battery problem. If the chassis alternator was sending only a fraction of what it should have to chassis/engine electrical system, then as you drove home the chassis 12 and 24 volt demands pulled electricity out of the chassis batteries. When you stopped to enter your property, there wasn’t enough electricity coming out of the alternator at idle and/or left in the chassis batteries to run the DDEC system on the engine and it likely went into some kind of safe mode and shut itself down (or the transmission shut the engine down).

So I would pause with the battery removal exercise and charging, and shortly someone will likely post about how to check out the alternator or challenge what I’ve posted.

If you want to forge ahead with the battery removal so you can charge them, you should be turning OFF the 12v and 24v chassis battery masters which I suspect are in the engine bay of an H Marathon as well as my XLV Liberty.

Here is a link to my suggestions about how to remove the batteries; page down until you find it. I thought I had a longer post about the subject, but I couldn’t find it today.

/threaddetails.asp?Category=&ThreadID=3749#33052

Regular people like us can safely remove and replace the chassis batteries if we take the proper precautions and do the process right. But keep in mind that if down wrong and/or without proper precautions it can be dangerous.

How did you try to “jump” the coach?

Where is “home”?

[Archived]

Your Alternator and or regulator are not working Jimmy, you ran the batteries dead. Assuming your batteries are still good, you need to charge with 24 volts or two sets of 12.

You may have fried your Equalizer when you shorted the batteries as well.

[Andy]

Thanks for the advice. Previously I actually called Marathon who told me to call Prevost who told me to call my local authorized bus repair facility who happens to be my neighbor. They’re right down the road and making a service call either tomorrow or Monday. The mechanic worked in Nashville for 20 years and works on a dozen tour bus Prevosts including a Marathon…plus hundreds of school buses. He knows my bus.

This job is way beyond my pay grade. I’m done and waiting for the local experts to help out.

Thank you all.

[Richard]

Jimmy,

Free advice. Have the technician start by separating the batteries, charging them and testing them individually after they have reached float. I CANNOT OVERSTRESS THE IMPORTANCE OF NUMBERING THE TERMINALS, PHOTOGRAPHING THEM BEFORE REMOVING THEM AND INSURING THE TERMINALS GO BACK TO EXACTLY WHERE THEY WERE BEFORE REMOVING THEM.

If you find any of the batteries are bad replace the set.

Next, diagnose the problem. Have the technician check alternator output. If a single alternator charges both house and chassis you might have been running the generator while on the return trip and it was the inverters that kept the house charged. If the batteries are charged by a dedicated alternator check the alternator and external regulator if equipped

When the system is charging again make certain the charging voltage is limited to the 27.7 volts specified in the Prevost shop manual for your coach. What I posted is a lot of work but if the batteries are bad you will not be stuck somewhere in the near future even though the charging problem is corrected.

[Tradewinds Coach & Marine]

Jon,

The service guy can’t get there until at least Monday. I will mark, label and photograph all the battery connections as directed. I will disconnect and charge the batteries individually.

Is there power I need to turn off first?

At what voltage should I charge the batteries? 2v, 10v, 40v?

I’m tempted to just go out an get new batteries using the PC NAPA discount just to be safe since the batteries are 3 years old. Your thoughts?

Thank you.

---

Tradewinds Coach
Kyle Bennett (Service)
Brian Miller (Sales)

[Archived]

There will be a toggle switch you can shut off in the tag axle bay labeled something like emergency disconnect, which is the same as shutting off the key…As you unhook each battery post, wire tie all the wires together on that post, wrap a shop rag around it, tape it up and label where it went. Then as you are disconnecting and reconnecting there is no chance of a short…

[Archived]

Jimmy,

Charge each battery at 12 volts individually, or if you have an on-board charger, 3 stage leave them all together and use the charger to re-charge them but at 3 years they might be getting tired.

[Archived]

Where to start? I guess in sequence. Dick from Wisconsin called to help out but we played telephone tag. Bernie emailed me to call him and we spent 25 minutes on the phone running through various tests. All the while, Bernie was kind enough to give his reasoning for each diagnosis…a great lesson for this automotive novice. Bernie was very perplexed because the bus should have started since there was plenty of juice in both chassis and house batteries which we tried to start using Marathon’s jump start. (Bernie was right, but that comes at the end of the story).

Impulsive guy that I am, I purchased 4 new chassis batteries and successfully installed them based on the advice of Dick’s previous post he linked above, Jeff’s similar advice to zip tie and wrap the wires with rags, and Jon’s input. Every wire was numbered and every connection was double marked both on the batteries and rag wrapped wires.

Coach still cranked over as before but wouldn’t start.

Bus tech came out, hooked up the computer and ran the codes. Nothing bad. After a series of tests, he figured that it wasn’t the batteries and that it was a fuel problem. Since I was parked on a decline, the engine wasn’t getting fuel so he said the first step was to add 30-40 gallons of fuel.

I called Coach-Net. They sent a truck out who added 30 gallons of fuel. Nothing happened. This guy was a former Greyhound employee and knew the H’s. He knew that the engine wasn’t getting fuel. He spent the next 2 hours taking apart both fuel filters…no fuel. He blew so much air into the fuel tank from both ports. Nothing. He unhooked and clamped off every fuel line. He was convinced air was in the line somewhere somehow. He kept checking to see if fuel was leaking anywhere but it was getting dark now. Miraculously, he got the coach running. Yea!

This tech also said all the batteries were good. Chassis batteries were cranking out 28.1 at the alternator even though dash gauge was reading 21.

Tech set me up with an appointment at another facility who could diagnose the bad gauge. So the following morning at 7:15, I start the coach right up and off I go. Man it’s fun to drive that coach.

One half mile later, the coach starts sputtering. I’m in the middle lane of a 3 lane road during morning rush hour traffic and the engine dies. No power steering but luckily I was able to pull of into the right lane and a half of shoulder. Hazard lights go on. I get on the phone with Coach-Net again and the first thing they ask is if I’m in safe place. NO. Cars are whizzing by at 60 MPH swerving at the last minute to squeeze into half the middle lane. All my road hazard devices are on the driver side bay. No way am I going to try to dig it out now. It was not a good day to die.

Luckily, Coach-Net alerted the police who sent a car out to divert the traffic. The tow truck arrived. Per Jon, I asked the driver if he knew what he was doing even though I didn’t really know the questions Jon would have asked. The operator Cookie towed many coaches including Alan Jackson and Montgomery Gentry’s buses. I could see he definitely knew what he was doing but that’s another post.

Final diagnosis. Detroit Diesel / Allison Transmission shop found a bad fuel shut off valve where fuel was leaking out and air was definitely getting in the line. Change the fitting and it’s running like…well, like a Prevost should run. Beautiful.

Now the battery gauge on the dash. Leon wasn’t available so I talked to Terry at Marathon Oregon. He said the dash gauge needs calibration and the local techs couldn’t do it. It must be calibrated at Marathon. If both inverters are reading good, believe them and not the dash gauge. My inverters are currently running at 26.7.

So I left with probably a faulty battery gauge but a good running coach. Sorry, I thought it was an electrical problem when all along it was a fuel line problem. And I now have a 2nd set of probably still good 3 year old batteries. Seems like a shame to turn them in for the $28 core refund. But now I should have another 5 years with the fresh set.

Lessons learned: First and foremost is that Prevost Community is certainly a community. To have folks jump in and so willing to help someone they’ve never met, it’s a special place with special folks. Thank you for all the posts and I can’t thank Bernie enough for spending time to run through the diagnosis.

I’ll never be without Coach-Net. What a great experience. In both situations, they followed up with every detail with a continuous series of phone calls. The truck is on its way. Is the truck there? The police are on their way. The wrecker is on its way. Are the police there yet? Is the wrecker there yet? Did you get to the facility? And more.

Keep safety equipment in curbside bays with easy access in case you’re stuck on a busy highway.

[Archived]

One of the hardest things to do is diagnose issues over the internet or emails, or even over the phone. Jimmy has proved that.

With our mostly electronic engines we need three things to get them to run. We need the engine to spin over. We need the electronics to work and to do that the ECM has to function and it needs power. And lastly we need to get fuel to the engine.

Get those three things going for you and the coach will run. Eliminate any one and you just become a road block.

Trying to figure which is missing sounds so easy after the fact and the information is provided, but as Jimmy so clearly points out it is difficult even if you are standing next to the coach.

Good post Jimmy. Glad you are able to drive the coach again.

[Fred F.]

What was the general location of the offending shut off valve?

Thanks!

[Archived]

Glad to hear you have it (mostly) resolved! Sounds like quite an experience.

Re: the charging voltages. I’m pretty certain that the 2, 10, and 40 settings were for current (amps), not volts. You always want to charge at the nominal battery voltage (i.e. 12 or 24).

I’m no expert, but my understanding is that the 2A current setting is kind of like a trickle charge. 10A is more aggressive and I start to worry about the battery heating up if you leave it too long. I’ve never seen a charger with 40A, usually anything more than 10A is a jump start setting and that’s usually a lot more than 40A. For a long-term solution, it’s best to have a multi-stage system that monitors the battery, as with the house batteries. For a once-in-a-while thing, I would say run it at 2A if you have the time.

Have you considered moving the emergency roadside stuff to the curbside?

[Michael]

My emergency “stuff” was in a drawer, behind a door which was also behind a door on the DRIVER’s side. I moved it to the CURB SIDE and labeled the drawer.