Voltage, well regulated, please...

I have noticed that when I start up the bus and let it run, I am seeing in excess of 15 volts on the gauges, both house and chassis batteries.

Additionally, my inverters shut off and the display for each indicates over-charging of the batteries.

So, am I correct in thinking that the voltage regulator needs replacement or simply adjustment?

And, if adjusting the regulator is the answer, how would it have gotten "out" of adjustment, or does this indicate that something is going on with the alternator?

Paul, I may not be the best person to answer this but I recently had a similar experience and found that the battery cables on the house batteries were corroded. I was at a repair facility in Eugene, OR and the mechanic diagnosed this as being a problem with my batteries. As a long-ago, ex-service manager I checked this out on my own and noticed the corrosion. Even though the mechanic, who insisted new batteries were in order, was reluctant to take the advice of an "amateur", did as I told him. That little correction eliminated the need for several thousand dollars in new batteries. As I understand it the mechanic is no longer with this company. This occured in August of this year. I have not had a problem since.
I am sure someone else (Jon?) will jump in and give you some more help and maybe better advice but this is what worked in my case. It certainly won't harm anything to check this out where making ill-advised adjustments might harm the batteries by overcharging them. Good Luck!!

Darl

Paul, your voltage regulator might be built in to the alternator. In this case you can just take the
alternator in and have it checked. Mine is a stand alone regulator so I just replaced mine when I had
irregular readings, mine didn’t adjust and was cheap! I’m not sure, but don’t think many do.

After replacing my Chasis batteries, I still had low voltage readings, the people at Gem Equipment in Ventura (Detroit Deisel & Allison dealer)diagnosed the problem as bad regulator. I ordered a new regulator from Prevost , replaced the old one. No more problems.

Dale...What is considered "cheap" on this forum? Remember, we're not all PPs.

Just kidding...Tomorrow I get to watch the "expert" work on Paul's coach. The Trukster is here and he'll perform a miracle for Paul

Speaking of miracles. Paul, since he purchased a Liberty, is waiting for the pope (JON) to appoint him bishop. i. e. Anyone who has a Liberty is closer to God than someone who doesn't.

Nothing else to write about except we proclaimed this a Micro-POG here at ODR. Truk couldn't believe that he ate his meal tonite and no attack came from any angle.

Paul,

Before you go running and changing alternators and voltage regulators I think the problem (if any) should be confirmed.

If I am correct you have a large alternator located between the engine and the AC compressor, and a second alternator located near or on the fan gear box. If that is correct, what are the odds that a dedicated chassis and dedicated house alternator and voltage regulator are both overcharging by the same amount.

My starting point would be to use a good multitester and check voltages at both sets of batteries.

Thanks for all the responses. We (Truk and I, with a cameo by the Lewster) will undertake the installation of the Guest Marine battery charger for the chassis batteries today. Should be painless and straight forward!

I don't know for a fact that the chassis batteries are being over charged by the alternator, I'll check the voltages with the bus running.

What I have seen, is that with the bus running, the inverters shut down, and the "blinking" panel for both inverters indicates an over-charging condition. I'm guessing that if the inverters sense too much voltage being applied to the house batteries that they then shut down and display this "over-charging" condition.

Since the inverters only do this when the bus is running, I'm figuring that the first place to look for a solution is the charging voltage from the alternator via the voltage regulator.

At least, if I can accomplish the charger installation, I can then be assured of being able to move the bus, should the need arise.

By the way.... I've yet to have the pleasure of attending a POG Rally, (we have a self-proclaimed Micro Rally taking place here, complete with a chassis electrical demonstration) but have any of you noticed Lews' love of garlic??? I'm wondering if the sod farm is a cover for a secret garden .......

We need to use precise descriptions of the situation. For example, with the bus running, is the coach still connected to shore power?

An inverter is a charger when it sees a 120V supply. An inverter stops functioning as a charger, and instead converts (inverts?) battery voltage direct current to 120V alternating current when that 120V supply is disconnected.

When it has shore power connected, and the engine is running, the battery charger portion of the inverter likely senses charging current from the alternator and reduces or turns off its output to the batteries.

So......step two in the process is IF there is a 15V house and chassis condition (which seems doubtful) is to turn off the inverters and recheck the voltage at the batteries.

Remember, the inverters have nothing to do with the chassis batteries making them an issue highly unlikely.

Quote:

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Originally Posted by phorner

I am seeing in excess of 15 volts on the gauges, both house and chassis batteries.

---

This kind of threw me a bit, chassis batts should be reading in the 26v range. Can you detail this reading.

We can not charge the chassis with the inverter but CAN charge the house with the 8-V if the equalizer switch is on.

However, the charger in the inverter will automatically adjust according to the state of the batteries and draw on them if supplied with a/c current while the engine is running and equalizer on.

If your house batteries were all charged up but chassis batteries were very low and the reg. has the charge rate cranked up and you have the chassis and house equalized that scenario may overcharge the house?

Just to add to the mix, how does the generator battery get charged?

Also, the bus was disconnected from shore power with the engine running, when the inverters displayed the "over charging" condition. I tried shutting them off, then back on, in an effort to reset them, but it made no difference.

If there was no a/c current being supplied to the inverters and they still displayed overcharge that would lead me to believe you have an inverter fault of some kind, that's just a guess. That is not to say that you don't also have another issue.

These are the most fun, simultaneous failures in a common system.

Your gen battery should be getting charged by the gen. alternator.

Our control panel also includes a second equalizer switch, but 12 volt, that enables us to charge the 12 volt bank of house batts. with the gen. alternator or use the house to jump start the gen. if need be.

If a/c current is being supplied and the inverters are on we can also send a charge to the gen. battery from the inverter by engaging the 12 volt equalizer switch.

This is all stuff that I had to figure out on my own through time and experimentation. Even though we received a full set of converters manuals many of these functions were not discussed and our converter, Hickox, is no longer around.

Joe, you are 100% correct with respect to your coach. We still don't know from Paul if he has 2 alternators so to answer his last question we need to make educated guesses so I try to remember to phrase my answers in that regard.

I think his generator battery is charged via the inverters when connected to shore power, and via the generator alternator as you suggest when the generator is running. This is a real gray area for me and I am speculating. I believe he has an isolator that separates that battery from the house, so the house battery condition does not adversely affect his generator start battery.

I think his engine charges both sets of batteries independently so I question his common 15 volts on each set of batteries.

Paul, Two alternators? What is actual voltage at batteries with engine running? With engine running and inverters connected to shore power what is the voltage at the two sets of batteries and the generator battery?

You should be able see slight changes in voltage at the batteries as you change conditions, such as engine off, inverters off, etc. because each regulator probably is set up for slightly different voltages. Divide the 24V side of the chassis by two.

The system that I have allows the generator battery to receive charging by

1. The Detroit running, is charging the house, cables connect house batts. to gen. bat. thru an isolator.

2. Generator is running, invertors are charging the house batts feeding current to gen. batt. like in #1

3. Shore power is charging house batts thru the inverter and feeding gen. batt. like #1

Note: a isolator allows current to flow in only one direction so the gen. batt. doesn't drain when the
house volts go down.

Quote:

---

1. The Detroit running, is charging the house, cables connect house batts. to gen. bat. thru an isolator.

---

so, does that mean defective (old and tired) gen batt could pull down the house batts, eg. when boondocking?

wmm

Unlikely Bill,

There should be an isolator. But with a battery tester it is easy to find the condition of the generator battery, or just take it off line by disconnecting it.

Almost 100% of the investigative work can be done with a multitester and some time. Back in the dark ages when I had issues, I would just isolate things one at a time until the problem showed up.

I don't have a clue as to how the generator battery is isolated in all coaches, but on my old coach the "isolator" between the chassis and house batteries for example was nothing more than a big solenoid (relay) that closed when there was charging current from the alternator. If the alternator was working, the house and chassis batteries were joined by the closing of the circuit through the solenoid (relay). As soon as the alternator stopped functioning such as turning the engine off, the solenoid (relay) opened and both sets were separated from one another. Classic simplicity.

I am sure there is some means of isolating the generator battery from the house as soon as charging of the house batteries stops so the generator battery and the house batteries can not adversely affect one another.

Bill, just when you are starting the generator. That is the intent of the cross over, to charge the gen. bat. and to use the house batts if the voltage in the gen. bat. is lower then the house batteries when starting the gen.

As an up-date, there are 2 alternators that are used to charge the batteries on my coach. With the engine running, and disconnected from shore power, the chassis batteries are measuring 27 volts, which sounds fine to me.

However, under the same conditions (engine running and disconnected from shore power), I am measuring 15.2 volts at the cigarette outlet in the dash, which is the only place that I could find to measure voltage directly. Additionally, my analog dash gauge for the house batteries also reads slightly in excess of 15 volts, which kind of confirms to me that the house batteries are being slightly over-charged when the engine is running.

Does this sound like a reasonable conclusion?

I have also found 1 voltage regulator, located on the bulkhead by the chassis batteries and the chassis battery disconnect switches which is adjustable, but I believe that this regulator adjusts voltage to only the chassis batteries, which appear to be OK, reading 27 volts.

Any ideas or comments?

My Alternator provides power to chasis and coach batteries thru the regulator. When the engine was running, and I had a bad regualator, the voltage to my coach batteries went way up into overload. At the same time, my chasis batteries were reading low voltage .

I am not certain, but I think the lighter may get it's power from the 12V side of the chassis battery system, the same as the 12 volt chassis lights.
On my coach the engine alternator will charge the house batteries at about 15 volts when the engine is first started. As the engine run time increases the charge will decrease slowly to 13.8 volts. The timing seems to be tied to the batteries state of charge. It never seems to stay high for more that 15 minutes max.

With two alternators the house and chassis batteries are charged independently.

I would rather see the voltage at the house battery posts, although it sounds like the house generator voltage regulator is in bulk charge, or there is a problem with it. I would not allow this condition to continue.

You did not say what the house voltage is with the inverters (on shore or generator power) only charging the house batteries, nor did you say how long after engine start the voltage reading was taken, nor the battery voltage prior to engine start.

When Liberty looks at the added wires, they should also check out the house battery voltage issue and I would be inclined to take the belt off that alternator while driving there.

I have to apologize to Paul and all others for a serious error.

PREVOST DOES WIRE SOME 12 GAUGE WIRES DIRECTLY TO THE CHASSIS BATTERIES, AND DOES NOT FUSE THEM AT THE BATTERIES.

I started digging through Prevost wiring diagrams (all 159 of them) and stumbled across some that show the very wires Paul has on his coach. According to the diagram they are 12 volt, 12 gauge wires going to several circuit breakers in the rear junction box and the DDEC3 feed.

They are not converter wires, and they are not installed after the conversion was done.

Jon, Don't be so hard on yourself ! A man with 2,695 posts theoretically could eventually have an "error." We will sweep it under the carpet and forget about it.

Jon, I am real happy to see this post for 2 reasons. One is that I believe you to be an honorable, honest, and helpful person. Your post just confirmed what we all know. I go along with Jim, don't feel bad. You have made a great contribution to POG, probably more than any other single person.:D Second reason is that in the course of trying to solve my on-going battery problem I have encountered these small wires attached to the battery posts. They go back into the loom like they were installed in the manufacturing process. I also have the DDECIII system so now I know my coach is normal.(or at least as normal as one of these things get).:rolleyes:

Thanks for all your help!!

Darl, the thing that tripped me up was the circuits that come off your batteries like Paul's, are shown as coming off the load side of the 90 amp 12V circuit breaker on the drawing I referred to when looking for a reason for those wires. On buses with the leads coming from the CB, there is nothing except the heavy cables attached to the batteries.

The moral of the story is never say never, look at ALL the Prevost drawings, and double check.

Jon, Thanks so much for clearing this up!! I do appreciate all of your efforts and you have absolutely nothing to apologize for!

I have an appointment in a couple of weeks at Liberty and was going to question them regarding these "mystery" wires and how they came to be installed in my coach. Of course, being a new owner, I feared the worst and assumed that someone had "tinkered" with my electrical system.

I now feel much better about their presence.

Thanks again for all your research and detailed analysis....

Jon,

You think you feel bad, I fabricated another board to cover my chassis batteries yesterday and low and behold, same DDEC wires that Paul had while I was in FL. I really didn't think I had them since I just wired in the Quest Charger and had everything apart, but I overlooked it and then told you mine didn't have them.:(

Sorry guys, I'll double check in the future before I open my yap....

Tonight, the individual charging of my batteries was complete and they were all in 13V range and holding. With the 12V and 24V switches off I began reconnecting the cables and the 'Jon' yellow wires. Since I only had a flashlight I was amazed to detect a spark as I connected the 'double wires-in one-connector' to the 12V battery located next to the big bolt/frame ground. I tried to follow the these 2 wires in the near-darkness but they disappeared inside the loom. I finished tightening the bolts on the batteries, including ol' Sparky, then turned on the 2 master switches. I also checked the all of the breakers next to the 12V and 24V switches. Of course nothing happened when I tried to start from the rear. Same results when I tried in the cab. The cab gauges remained the same as they were when this problem began. I then disconnected the offending yellow 12 gauge wire from the battery post and then went through the same starting procedure as I described above. Same result.

Obviously this yellow wire, attached to the + side of the battery, is either grounded or or I have a closed switch someplace on the coach. Tomorrow I am going to go through the 159 diagrams unless Jon remembers something about this and can suggest the diagram number. I would have a mechanic look for this problem but, to my knowledge, we don't have anyone in the Reno area that knows anything about a Prevost.

Will the factory or the Prevost service center in CA give some advice or guidance in a case like this? This problem might require a lengthy dialog. At this point that might be my only option unless my towing insurance is willing to do a 600 mile tow to Prevost. Sure! I do have a Good Sam breakdown policy but I don't think this is something they would pay. Any ideas appreciated...again.
Thanks,
Darl

Darl.....here I go again. I hope it is right this time. If you are going looking I am using pages 91 and 95 of the 159, drawings D060873 rev 022 P.1 and D060873 rev 24 P.2 respectively. I have no clue what serial numbers these revision levels include, but the areas of concern do not seem to have been revised.

With respect to the spark, the 12 ga. wires coming off the 12V post go to CB19, CB20, and CB21. Your listing on the bus rear door should tell you what they are for and from that you can determine if they are hot. The second lead goes to the DDEC feed.

That may explain the spark. It would be worth while to measure the amps just to get a sense of how big the load is, although with freshly charged batteries it likely has nothing to do with the starting issue.

As to the starting question, on P.2 you can trace the start circuit power from the rear junction block (RH side of the drawing) through CB16 to the rear start switch. Obviously if there is not 24V at the wire number 89 at the switch or CB then something is wrong, either the CB is open or the power is not getting into the rear box. If there is no power there then the problem must lie with the big breakers on that stainless steel panel above the master cut-off switch.

For the moment I will stick with my previous guess that it is the 90 amp breaker. BTW.....Kim Sloan owned my coach originally, and he was very good at revealing a little of its history. One of the things that showed up very early in the life of the coach was the breakers shown as 90 amp on the drawing were failing evidently because they were near their limit. After a couple of scary incidents on the road where his coach shut down, Prevost replaced the 90s with 105s. He said the problems went away.

I am not focussing on the breakers because of that, but that may be a clue as to the problem. The drawings clearly show a failed breaker will shut off power to the rear box and along with it any power needed to engage the starter.

I think we jumped threads for Darls problem, but I'll stay on this one.

Darl,

I think Jon is dead on with the CB. Try these steps just to get started unless your well beyond this..

1. Power to the Jump Lug is before the cut-off switch and should be 24+

2. Voltage at the big red terminal on the starter/solenoid should be 24+ and that proves the cut-off switch is working

3. Remove the plastic panel behind the CB's and check that current is passing through as Jon suggested. You can't just push them, put a meter across and verify. On mine, CB6 goes to the junction box.

I'll leave the rest up to Jon so as not to muddy the water.

Darl: On My Royale I had similar yellow wires directly connected to the batteries. I moved them to the 24V disconnect switch so they will be off with the switch open. No apperant problem developed after doing this, except the batteriers stay charged with the switch off. I think I traced the wires to the inverter that changes 24V to 12V for the headlights. We don't need headlight power when parked with the switches off. I am no electrical guru for sure, but this worked for me. I leave a 24V "Battery Tender" on the starting batteries when parked.

Truk, no problem jumpin' in because both your coaches are closer in age. I have stopped referring to my coach and I am trying to stay with the wiring diagrams that seem to most closely relate to Darl's.

I don't think Darl needs to spend the money for a tow or repairs because this thing is due to a single problem, as yet unidentified. I believe we can all work through this and get him running again.

Harry, I think you did the right thing. That is exactly how Prevost has done that on some coaches (and why I screwed up so bad) and their wiring diagrams show those wires at the big CBs.

Tom, Jon, and Harry, thanks for the great advice. I have to take my wife to the Dr. so I will check this out when I return and post the results. I certainly don't want to go to the expense of having someone poking around for something they don't know about and charging me a fortune. What all of you wrote makes real good sense. The weather has changed a bit so hopefully it will cooperate while I work on the home. Thanks again!:)

Darl,

Here is the procedure I would use to check this, and why.....

I assume your batteries are up to their desired voltage and are connected according to the Prevost diagram. Obviously this is essential to insure you get the right voltages to the 12V and 24V circuits.

Verify 24V at the big cable on the starter. This proves the 24V master is closed. This cable does not go through any CBs, just through the 24V master switch to the solenoid.

If OK, verify 24V is in the rear electric box. This is essential. If it is not, it means power is not getting past CB6 (that number may need to be verified, but it is the CB that feeds the rear box.

If OK, and there is 24V power to the rear box, power to the rear start switch passes through CB16 (again verify that number). If there is power to the rear start momentary contact switch, there should be continuity between wire 88 at the momentary contact start switch all the way to the starter relay coil R4. If OK there is no reason to not hear a click when the engine control switch is in the rear start position and the rear start switch is pushed.

If there is continuity and it has been confirmed, if a push on the rear start button does not produce a click in the R4 relay the relay may need to be replaced. If you hear the relay, and the starter does not engage, check for 24V at one side of the R4 relay. This should be at wire 24R, a 10 ga. wire. The other side, wire 86 goes towards the starter solenoid.

I still think you are going to solve it where I have highlighted it in red. I got my neck stuck out a country mile on this Darl, and if it turns out different than that, do me a favor and lie so it looks like I know what I am doing.

Jon,

Your wire numbers are identical to my 99 chassis and should match Darl's.

I am back at my office for a while but I stopped at home for a bit when I came back from the Dr. I removed the cover on the rear circuit breaker and with some limited testing found that I only have 12V back there including the 24V switch. I tried CB6 and had nothing. Tried with both master switches on and off. Still nothing. This may be just as you all suspected from the start, a circuit breaker. Now, my questions are; if this has indeed failed (I will double check it in the morning) should I replace it with a 105amp and where do they sell this type of breaker? Smith Power Products, Detroit Diesel does the service on my Prevost but they order the CBs from Prevost.
Again,everyone, thanks for all your help. I hope to return the favor one day soon!

Darl,

It may not have failed. It probably tripped, but you haven't got enough force in your thumb to reset it if it is like the ones on mine. I had to hold a screw driver flat blade on the face and push like hell with both hands along the length of the screwdriver. It hardly moves when it resets, but there is a distinct snap so you know it reset.

If it did in fact fail I would replace it with the same size unless the coach has had problems which I doubt.

Darl,

The guy that nailed this from the git-go, if it is in fact the CB was George (Toy Box). The only reason I came back to this was I think somewhere you said the CBs were OK, and my look-see at the wiring diagrams kept bringing me back to what George said.

Good job George.

Darl,

The question is:

Do you have 24+ volts between the master switch and one side of CB6?

Tom,

The answer is:

NO

I only have 12.8V on any place I could check throughout the CR area or at the starter. I have not made that specific check yet. I am going to try the Jon starter/screwdriver trick on the CB6 when I get home. If that don't work I will check the voltage between the master and the back of the #6 breaker. I have been looking for a 90amp CB here in Reno but to no avail. I just signed up to buy parts from Prevost direct in case I can't get the the CB reset. Thanks for your help Tom.