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Jeff Pulls My Fat Out of The Fire Again!
We pulled out of the Fying J in Effingham, Illinois after spending the night nearly two weeks ago and had not driven 5 miles when a dash warning light came on that I had not noticed before. It said House Batteries Low. What? How could that be?
First, my batteries have been in great shape and when the batteries are good we have enough battery power to run an air conditioner for several hours without plugging into electric. After we turned off the generator at bed time Monday night we ran the fan but no air. The batteries should not be low.
Second, IF the batteries get too low the generator was set on auto and should start and run. That did not happen. Therefore the batteries should not be low.
Third, when the batteries were bad three years ago and they did get very low this House Batteries Low light did not come on then.
All this went through my mind in about 10 seconds while I was looking for a place to get off the road.
I pulled into a very conveniently placed rest area and went to the electrical panel to check the inverters. Both inverters were in error but the house battery voltage was not low. It was high. Evidently the warning light is for low AND high house voltage. I thought something might be wrong with the inverters so I cleared the errors and started the generator to see if things would even out. Nope, right back into error for high voltage on the house batteries.
The eight 4D AGM house batteries are too expensive to boil. I turned off the engine and the over charging of the batteries stopped immediately. Ok, there is a clue, Shaggy. No engine, no overcharging.
That told me there might be a problem with the bus alternator. I went to the back with my voltage meter and had my wife crank the engine and the alternator was putting out 35 to 37 volts instead of 25-27. Oops, that is not good.
I checked the wires and connections and everything seemed good. That was pretty much the end of my trouble shooting ability. That’s where Jeff Rowe comes in. I brought him up to speed and he had me do some additional tests. With the information I gave him Jeff came to the conclusion that the external voltage regulator was probably bad.
More importantly at the moment he told me what I needed to do in order to roll. He told me to disconnect the field wire so that the alternator would not charge and then instructed me on how to proceed. I turned on the 24 volt trickle charger I installed last August, cranked up the bus and rolled on down the highway.
The trickle charger kept pace with charging the chassis batteries as long as we did not run the bus air conditioning or the headlights. We ran the generator all day to keep the house batteries charged, run the roof airs and to have power for the trickle charger. We needed the trickle charger to top off the batteries over night so when we stopped that night we plugged up in a campground.
We tried to find a voltage regulator in St. Louis, Springfield and Tulsa but no one we called had it in stock. I finally ordered it from Prevost and had them ship it to my destination at the end of the week. I had to travel like that for two more days but we made it fine.
Just for information the Prevost part number for my voltage regulator is 563439 and the Delco or Detroit number is 10503805.
I installed it when it arrived and it did not solve the problem. That was not Jeff’s fault because he did not know a crucial piece of information and I did not know it was important. The alternator does not go directly to the batteries. There is a multi-battery isolator installed between the alternator and the batteries with another lead going from the isolator to the house batteries.
Model 3002
When I mentioned that to Jeff he knew exactly what the problem was. It had to be the isolator.
When I checked the voltage I had 37 volts coming from the alternator, 37 volts going to the house batteries but only 24 volts going to the chassis batteries. Since 24 is not enough the voltage regulator was doing its job and telling the alternator that more power was needed. The alternator was cranking out more power but that power was not getting through the isolator so the house batteries were getting too much and the chassis batteries too little.
That was on a Monday I did not have to roll till Saturday. Jeff got one to me and it was a simple install Friday morning. I have a “24 Volt Emergency Alternator Disconnect” that cuts the connection between the isolator and the house batteries so with it off and the chassis batteries off the isolator has no voltage.
I sent a quick text to Ben Cummings to confirm that. I appreciate his reply and willingness to help and Diane getting his number to me.
The change out was easy. I labeled the leads, took pictures, removed the leads, taped the ends and tied them up out of the way. The isolator was fastened to the floor with two bolts with nuts underneath. Both bolts broke on the first turn which I half way expected. (I feel like I am going to break after not moving for 20 minutes and these bolts have been on 20 years.) I sent my wife to the lumberyard for bolts while I finished.
After the new one was bolted in I cleaned the leads and hooked it all back up.
It was 30 minutes start to finish including my wife’s trip to the lumberyard. It took longer to get my tools out and put them back than to do the job.
The really good news is that it worked. Jeff pulled my fat out of the fire again! Thanks much, friend.
As I type this I am back at the Flying J in Effingham 5 miles away (And a 1655 mile loop) from when this problem started.
I adjusted the voltage regulator down a touch yesterday but it is still running a shade over 28 so I knocked it down a tad more after I stopped last night. I will finish the run to Ohio today and see what it does.
Davy
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22 Replies
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Great story Davy, can you imagine someone without the resources here on PC and without help from people like Jeff and Ben. That person may have been broke down for days with no place to go that even knows what a bus looks like, not to mention cost.
Good job, you probably never thought you would turn into a wrench did you?:)
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Tom,
I am very thankful that Bob Glines sent me here within the first month of Prevost Community going live. It has and continues to be a great blessing to me personally.
I have never been and probably will never be mechanically inclined but it is amazing what we can do with a “little” help when we are put into a bind. (Grin)
Davy
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On another thread we have had discussions about how we all can have a network of people to call for help. It was started because of someone having a medical issue and the wife needing assistance in getting the coach home. Davy’s post highlights how having such a network can help him resolve mechanical issues.
Other than members creating personal relationships with other members and service people like Jeff and Ben I cannot think of any other way for all members to have a “safety net”.
This is directed to those who read the forum routinely, but who rarely or never post. We don’t know you. And unless you have attended a rally or have met someone in your travels we won’t know if you can help us or if we can help you. At the very least I would suggest you participate on the forum in some way. Don’t be afraid. Nobody will pick on you if you ask basic questions or can’t spell. By participating we all get to know one another and we get to add names to our list of people we can call for help.
While we never make email addresses available, if a member wishes to communicate with another member we have acted as intermediaries and let one member know another member would like to communicate via email. That way if the member wishes to correspond we have provided the first person’s email.
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Could not agree more with Jon. Having a resource such as PC and the dealer/service places that have frequently been mentioned and helped out that have shown they are up to the task on multiple occasions, gives me the confidence to buy into the Prevost thing (rather than SOB) knowing that there is plenty of help & advice available to help out. Not having to rely on people & companies that probably don’t have a clue will be a huge bonus.
All this in a country 3000 away from home as my plan is to use the bus to tour the USA .
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Here is the list of people and places I would consider to be a resource if I need help. The list is not in order and who I might contact for help is going to depend on the problem.
Prevost PASS
Detroit Diesel 800 number
Allison Transmission 800 number
Service providers like East TN Luxury Coach, Tradewinds, Parliament (Ben or Rick), etc.
My converter
Owners of my specific conversion and chassis type
Friends I know who live in the area
Friends I know who will drive my coach
There may be others I might call, but as you can see the type of problem or need is going to determine who I call and what help I might expect from the call. Contacting other PC members may not always be because of an emergency. Many of us have asked someone to look at a coach as a preliminary inspection to see if it is worth traveling a long distance to buy. I have checked on the progress of repair work for others. Sometimes we just want to meet for dinner. Whatever the reason it is valuable to create our own list of those we can network with.
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Great post Davey and so so true. The pictures add greatly to my understanding. I haven’t had the pleasure of meeting Jeff in person yet but look forward to it at next months seminar. Jon your suggestions are great as always and I now have all that contact information easily accessible for myself and Becky. -
All went well on the trip from Kansas to Ohio. It was 814 miles total and everything seemed to be charging, regulating and distributing well. Since I had no alternator on the way out I could not run the Prevost AC. With the generato powering the roof airs it was hard to keep the windshield below 85.
It sure was nice to have my Prevost AC back this weekend. It was nice and cold like I like it.We were in direct sun this morning. With Prevost AC the temp on the atomic clock in the windshield was 89 when we started and 74 in a little while. Sweet!
One question. I have been adjusting the new voltage regulator on the way back and it seems to go down 2/10-3/10 of a volt with every half turn. What is my ideal target voltage at the alternator?
Davy
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Davy…
So glad you got it all worked out !! Safe travels to you and your family !!
Diane
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Davy,
The Prevost recommended voltage regulator set point is a steady 27.5 volts. That should be at a fast idle RPM or higher.
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Thanks, Jon
Davy
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I don’t necessarily trust the accuracy of the gauges so I would verify the voltage at the equalizer or batteries.
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Good reminder. That is what I am doing, checking in the back with a volt meter. I am going to verify with second volt meter but I will be away from the bus a few weeks starting Wednesday. To be continued…
Davy
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Postscript………..
I am not familiar with how Vantare set up the gauges for the house so I don’t know how much Davy could determine from his gauges, but Jeff’s explaination of what happened was a real eye opener.
The way Davy’s coach is set up alternator current flows to the isolator, and from there it goes to the chassis batteries on one side of the isolator, and to the house battery on the other side. The voltage regulator is connected to read chassis battery voltage in between the isolator and the batteries.
What happened is the current from the alternator was not flowing through the isolator to the chassis battery output. As the chassis battery voltage was depleted because it was not being charged from the alternator through the failed chassis side of the isolator, the voltage regulator was reading the reducing voltage, and was calling for the alternator to put out more voltage. The voltage was in excess of allowable limits because the voltage regulator was not able to regulate it because its reading was from a side of the isolator not passing current. As a result the house batteries were in danger of being “cooked” along with all the house electrical system.
The lesson for me is as soon as a warning light appears on a single alternator coach, do a quick check of both the house and chassis system voltages and be prepared to shut down if required. Jeff and Davy worked together to determine what had happened and Davy did the right thing to shut down. It saved his batteries on the house side an possibly the wiring also. Jeff did a good job of identifying an obscure problem that could have had very extensive consequences.
Good job guys.
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The bus has been sitting longer than any time in the 7+ years I have owned it. We were gone on vacation with extended family two weeks and then we had to fly the next three weeks of revival. We have been in meetings near home the last two weeks and I drove the bus short distances but today we blew the cobwebs out good, 610 miles. That is about 60 miles over my self imposed limit but I am headed into triple digit temps and I wanted to get there early tomorrow while it is still coolish.
After about 220 miles I checked the voltage and it reads 28.3 at the alternator lug but 27.6 at the battery screw on the voltage regulator. Do I need to turn it down some more?
Davy
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Davy,
In round numbers Prevost has a 27.7 value for voltage on the voltage regulator in their service manual.
The 28+ voltage exceeds that. Knowing the distance between your alternator or isolator to the chassis batteries my concern would not only be limited to the voltage, but why you are experiencing the voltage drop in such a short distance. If you are measuring at the house batteries the cable run is much greater, but it still does not explain the voltage drop.
Having said that the voltage at the batteries is not harmful to them, but if it is 28+ at the batteries then you might have issues because your batteries are being charged at a constant bulk rate voltage for as long as you are driving. That has the potential to cook the batteries.
My first response would be to check all the cable connections, and specifically the big ground post on the frame behind the chassis batteries. Make sure all connections are clean and tight.
Then adjust the voltage regulator to bring the alternator voltage to the value specified in the Prevost Service manual for your vintage coach.
Jeff? What is your receommendations?
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