Does Generator Charge Bus Batteries??

[Ray Davis]

This is a bit of hindsight, and maybe some conjecture. In May of 2006 before heading off on a 1 week trip to Salt Lake City, I thought it would be good to have my A/C's serviced.

I took the bus to Prevost Mira Loma, and serviced the cruise airs, and the Country Coach A/C system. The filled it with R-12.

Well, there was a placard on the system which indicated there was some other refridgerant in the system, not R-12. Will Garner recently indicated the same on his system, it's like R-422 or something. It was very hard to read, I'll admit, but the techs didn't look at that, nor check what was in the current system.

At about 5 hours of use, the compressor completely froze, snapping all belts. My alternator was an external alternator, driven by a belt which also hit the A/C compressor, so when I lost that belt, I lost A/C and alternator at the same time.

Thus began a saga of many months and many thousands of dollars getting that A/C system working again.

So, the alternator was never a "problem", just I couldn't run it due to the A/C compressor being frozen solid.

Ray

[Ray Davis]

am seeing some odd battery lights after several days sitting

Is your equalizer possibly having a problem? The equalizer takes the 24V output from your alternator, and splits it into the two 12V sections of the chassis batteries.

If they are not charging equaly you will get a warning light. My older coach used to say "12/24 volt imbalance". It would flicker on rarely from time to time, but never stayed more than a few seconds.


Ray

[truk4u]

Bruce,

Unless you have something different, you have one 270 amp 24 volt alternator that takes care of both house and chassis when the engine is running. You will have 2 equalizers, one in the engine compartment and another probably adjacent to the house battery bay, because you have series/parallel setups for the chassis and house. Mine was in the battery compartment accessed by a panel. If you have that light coming on, you may have an alternator and/or regulator problem. You need to get it checked out by someone Prevost qualified and not Bubba's Truck Emporium.

[Jon Wehrenberg]

Bruce,

First, you need to know if your coach has one alternator or two. If it has two, you need to determine which is for the house and which is for the chassis. The chassis alternator is the one that is kicking on the warning light.

If the light is temporary, and you have a chassis battery charger, do not try to chase a problem because you will end up being frustrated and if someone tries to solve the problem you will also end up broke. Save your money for Canadian Diesel.

The reason I mention a chassis battery charger is because when the alternator or voltage regualtor finally dies you can maintain a charge on the chassis batteries by running the generator or using shore power to operate the charger until you can get to a service facility. I don't agree with Tom. I would look for the best alternator shop that handles your size alternators. They are experts and likely a lot cheaper than Prevost.

[0533]

I get the 270 alt light on for a few seconds usually about an hour into my first trip after sitting for a while.

I seem to have one alt. 2 equalizers both in the engine compartment, all connections look good, checked them all tight.

I do however get a surge in my fan blower motor at the dash when there is a problem, the amps are at 28 or 29 but I get this pulsing of the blower and it also makes the amp meter its self flicker back and forth.

I am thinking that I may have a bad chassis battery and when I first start up it is not fully charged or balanced, don't really know.

Thanks.

[Jon Wehrenberg]

Bruce....are you talking amps or volts. Nobody can help you if we are not on the same page.

Also, how do you know the blower is what is making the amp meter? flicker back and forth?

One alternator, with two equalizers tells me you may have a 24 volt coach. (I'm talking house here because all our coaches are 24 volt). So what you are calling an amp meter, could it be a volt meter? If so 29 volts is pushing the high side of the range. That suggests to me, if I am able to interpret what you are saying that your alternator could be a problem, but I would not rule out the regulator. In fact if it is voltage and not amps I would monitor voltage very closely. If the regulator or alternator should fail such that you have excess voltage it can have a serious damaging effect on a lot of your devices. An intermittant or occasional glitch is difficult if not impossible to trouble shoot. The pulsing you describe may be the voltage varying and the blower motor reacting to the change in input voltage.

If the voltage gets excessively high (29 volts is at the absolute upper limit from my perspective) I would recommend disabling the alternator. Either disconnect the field wire from the regulator or remove the belt if it does not drive something else.

You can easily check the equalizers and put your mind at ease.

Connect your voltmeter (multi-tester) black lead to a ground (on the equalizer is OK), and read the volts at the 24 volt post and the 12 volt post on the bottom of the equalizer. The equalizer is OK if the 12 volt post is 1/2 of the voltage at the 24 volt post, +/- 1/2 volt.

[truk4u]

I don't agree with Tom

Really! OK, take your bus to Archies Alternator Service and when you open the engine compartments and he say's "Damn, nera seen notin like this, what the hell is those things?" And, "dats the biggest nator I era seen, what the hell is that oil line fur?"

Watch your wallet Bruce...

[0533]

Bruce....are you talking amps or volts. Nobody can help you if we are not on the same page.

Also, how do you know the blower is what is making the amp meter? flicker back and forth?

One alternator, with two equalizers tells me you may have a 24 volt coach. (I'm talking house here because all our coaches are 24 volt). So what you are calling an amp meter, could it be a volt meter? If so 29 volts is pushing the high side of the range. That suggests to me, if I am able to interpret what you are saying that your alternator could be a problem, but I would not rule out the regulator. In fact if it is voltage and not amps I would monitor voltage very closely. If the regulator or alternator should fail such that you have excess voltage it can have a serious damaging effect on a lot of your devices. An intermittant or occasional glitch is difficult if not impossible to trouble shoot. The pulsing you describe may be the voltage varying and the blower motor reacting to the change in input voltage.

If the voltage gets excessively high (29 volts is at the absolute upper limit from my perspective) I would recommend disabling the alternator. Either disconnect the field wire from the regulator or remove the belt if it does not drive something else.

You can easily check the equalizers and put your mind at ease.

Connect your voltmeter (multi-tester) black lead to a ground (on the equalizer is OK), and read the volts at the 24 volt post and the 12 volt post on the bottom of the equalizer. The equalizer is OK if the 12 volt post is 1/2 of the voltage at the 24 volt post, +/- 1/2 volt.

Thanks Jon, It must be frustrating to try and talk a challenged POG member through these types of questions.

You must have been a kindergarten teacher in another life.

The meter I am speaking of is the Prevost battery meter in the dash panel.

I will test the equalizer just as soon as I purchase a multimeter and learn how to use it. I think a stop at a NAPA store is in order today. Maybe I need a shopping list. Canada has more NAPA stores than grocery stores.

Truk: When I took the ferry from PEI to NB, and when I was entering the ferry I scraped my genst exhaust dislodging 4 brackets. Went to a really nice truck stop, excellent people, they stopped what they were doing and got right under and fixed the brackets, better than new.

While I was there I asked the manager if they could inspect the altenator and equalizer and see what was up. Well, how did you know that I went to Archies truck shop?? And how did you know what they would say when they opened the engine compartment. "Damn, nera seen notin like this, what the hell is those things?" And, "dats the biggest nator I era seen, what the hell is that oil line fur?"

[Jon Wehrenberg]

Bruce,

I am sure our dash gauges are different, but in my coach my chassis voltage gauge has a needle for voltage and a needle for amps.

Any advice is only as good as the underlying explaination of the problem.

Your issues are exactly what we will be covering in a seminar at Spearfish. The intent of the seminar is not to solve problems, but to help an owner understand exactly what information he should be looking at relative to the electrical systems and how to interpret what is right and what is wrong.

You are jumping before you even realize you are jumping. I make that comment based on the fact you are focusing on equalizers. It's OK to check them, but don't expect any eureka moments. I doubt if they have anything to do with the problem you are trying to describe.

If you have a single alternator, when you are traveling down the road you should see the same voltage for the house that you see for the chassis. Here is where you need to react and get concerned. Depending on the type of house batteries you have, your high voltage (if that is correct) may be hurting your house batteries if they are gel type.

I have not ignored your concerns about chassis batteries going dead. I suspect all of this is tied together, but I just don't know how because there is so much data lacking.

Do you really have just one alternator?
Is your chassis voltage really 29?
Is your house voltage 29 also?
(These are voltage values only with the engine running, but the shore power and generator off)
Do you have a 24 volt house?
Do you have OTR?
Have you physically checked your alternator and regulator connections?
Are your house and chassis battery connections clean and tight?
Have you checked you batteries?
What type house batteries do you have?
Can you get the key off loads on the chassis batteries measured? If the batteries are being depleted there is either a bad battery or a load. That current draw needs to be measured.

The alternator light that is coming on is telling you something. When it comes on if you instantly look at the electrical gauge what are the volts and amps? Are they higher or lower than normal?

What is the chassis battery voltage as measured at the battery posts compared to the dash gauge?

Before focussing on anything it is critical to gather information.