MISCELLANEOUS POOP

[Jon Wehrenberg]

As hard as I try to avoid surprises $hit happens.

I recently replaced all brake chambers because they were 5 years old. That is the schedule I have chosen for myself. The shop manual calls for replacement every 100,000 miles or every year, whichever comes first, but I am comfortable with my choice of time.

My driveway is my test track. I figure if my brakes will hold the bus from going down the driveway they are OK and obviously my new brake chambers were OK. We just completed a 1250 mile trip on the brand new brake chambers and after I fueled up at the Pilot before putting the bus away I heard a whistle when I applied the brakes. I knew something was not right.

It turned out that one of my new drive axle brake chambers has a leak that I think is either a failed diaphragm or the diaphragm, when installed was not installed properly and is no longer in place. The moral of the story is it happens. BTW, a DOT brake check revealed this. Good to know all the brake checks aren't a waste of time.

On another subject, I recently went to extended life coolant and in doing that I used radiator flush to insure my radiator is clean and will go the six years I intend for the coolant to be in the bus. The reason I went that step was in the last year my engine coolant temps had started uphill, only by a few degrees, but enough to notice. I have been watching them closely but really could not pin down if it was a problem or not. If it was a problem I did not know if it was related to the radiator, the engine thermostats, or possibly the fan clutch.

On our trip (mentioned above) the temps were about 80 to 84 degrees outside and I noticed the fan (or thermostats) appeared to be cycling on and off at a temperature that was 5 degrees higher than normal. On my coach the low speed cut in temp is around 204 and the high speed fan cut in is around 208. Some coaches have lower temperature settings, but that is related to the engine serial number. I would typically see my temps run a low of about 195 up to the 204 degree cut in point. All of a sudden I am seeing temps 210 and above.

So before returning home I locked the fan using the two 6MM bolts located in the end of the fan drive shaft.

The temps all the way home cycled at the coolant thermostat temps of 190 to 195. So yesterday I spent some serious money for a new clutch. The old one is rebuildable so after the installation I will rebuild the old one and keep it as a spare. I am guessing the electro magnet that locks the fan up is the problem, but I will replace the bearings also. Apparently our fan clutches do exhibit wear because they are constantly cycling on and off. With the fan locked up my Pro Driver told me I lost almost 1/2 MPG so it won't take long to pay for that clutch.

And since bad luck seems to come in threes my back up camera monitor died. I have bought monitors from RV Cams over the years and while I don't like spending the money to replace them I can sing the praises of Tim Lazaroe who does an outstanding job of customer support. If you need a new monitor or want to upgrade your old back up camera system don't hesitate to deal with Tim at RV Cams. http://www.rvcams.com/Default.htm

[BrianE]

Thanks for the pertinent poop Jon. I too experienced an immediate failure of a brake chamber. In my case it was a tag lift chamber and fortunately I discovered it was defective immediately when I did a function check after replacing it. Without a function check it probably wouldn't have come to my attention until I noticed that tag tire having excessive wear. Am pretty sure these units are assembled south of the border.

I am also very high on Tim at RV Cams. He really knows his stuff!

[Ledo]

Jon I hope I'm not the only one asking but would you elaborate the procedure for a DOT brake check. Looking forward to meeting you in Austin.

[Jon Wehrenberg]

The purpose of a brake check as part of a pre-trip inspection is to determine if there are any air leaks in the brake system. I'm simplifying it but it essentially requires the bus to be aired up. Engine off. Assuring it will not roll, release the emergency (parking) brake. Note the pressure drop and verify the air systems do not lose more than a pound or two of air pressure per minute (I forget the real value, but it actually should be no pressure loss) after release and initial pressure drop. Just as a tip, if you do this and hear any sound of air escaping you don't even need to look at the gauges to know you have a problem.

Upon completion of that check apply the service brakes and hold them. Again there should be a small pressure drop and then the air systems should not lose more than a pound or two per minute. Like before there should be no pressure loss apart from the loss during brake application and you should not hear any air escaping.

Once satisfied the service brakes are not losing air, fan them and observe the pressure loss. As the brake systems air pressure drops through 60 or 70 pounds the audible and visible alarms should come on. Continue fanning the brakes until the air pressure drops to about 45 or 50 pounds at which time the emergency brakes automatically apply. The yellow knob will pop up and you will hear the discharge of air associated with emergency brake application.

This procedure is spelled out in detail in all state commercial driver license handbooks and it should automatically become a part of any pre trip inspection.

For those new to the Prevost you should at least know some basics. When your bus is parked, the emergency brake is on and you do not have the service brakes applied there is no air pressure to your brakes. The emergency brakes are applied by spring pressure. That is important to understand.

When you wish to drive and you release the emergency brake, you are compressing the spring (a very heavy and powerful spring) with air pressure. As long as you have air pressure you can release or disengage the parking brakes. The service brakes work with the application of air pressure. Your food pedal is essentially an air valve that tells the service brakes to be applied via relay valves close to air tanks and the brake chambers. Because everything mechanical can be expected to fail the pre trip brake test allows you to verify everything is working as intended and you have no air leaks. The reason air leaks must be found is if a leak occurs it may be possible for the leak to increase in size to the point where the bus engine driven air compressor can no longer keep up with the leak and when that occurs air pressure will drop and the air brakes are going to automatically be applied. You cannot buy that kind of excitement.

When driving your air gauges will tell you some things apart from the test. If the air system gauges are cycling from the max pressure of 120 to 125 PSI down to the compressor cut in point of around 100 PSI frequently, and you can see the needles track downward you have a leak that needs your attention. While the bus has protection against auxiliary air system leaks and is always going to maintain at least some brake system air pressure, every leak should be identified and corrected. Since the emergency brakes require air pressure to release them it is especially important to monitor that system because a small leak in an emergency brake diaphragm or air hose for example can quickly turn into a leak exceeding the compressor's ability to provide air pressure. At that point you either have to "cage" the brake in question and block the air flow, or have someone do that or end up on a hook or flatbed. You cannot drive if you cannot maintain air pressure. If you should ignore all the signals and continue driving as your air pressure drops toward zero the emergency brakes are eventually going to be applied automatically. This will not cause the bus to stop instantly, but it will stop and fairly quickly. On dry roads you will likely retain some directional control. But if you have the application of the emergency brakes on wet or icy roads make sure your seat belt is tight because it is likely the rear wheels will lock up at which point you switch from being a driver to becoming a passenger.

So for a few minutes of time prior to a trip you can save a whole bunch of grief.

As it turns out on my coach the problem was my new 30-36 brake chamber was leaking at the diaphragm and all I had to do was cage the emergency brake, and tighten the clamps on the service brake chamber. Apparently the manufacturer did not sufficiently tighten the clamps and in one trip the leak appeared. I'm just glad it was evident 3 miles from home so I did not have to deal with that issue when on the road. It wasn't a big leak so I still had plenty of braking available to get the bus in the garage.

Anyone that knows my driveway understands when pulling out of the garage to go on a trip I have the best pre-trip brake inspection available during the 300 foot downhill run. That to me is great motivation to get in the habit of a brake check because a brake failure on that hill will be an interesting event.

[Jon Wehrenberg]

Just to add a real life story to this we were coming through Charlotte NC many years ago in our first bus and I noticed the air pressure gauges were cycling up and down much more than normal. To put this in perspective that bus had air wipers and it was raining so that cycling was expected, but it soon got excessive. That got my attention, but I did not know what could be wrong.

In a fairly short period of time, maybe 1/2 hour I started losing air pressure. When the traffic started to slow, my RPMs went down and it became evident at lower RPM may air pressure was dropping to the point where I would be getting emergency brake application so I got off the road into new construction about 3 lanes away from the traffic flow.

As it turned out the drive axle brake chamber emergency brake diaphragm failed. I had to cage the emergency brake, which means retract it using the T bolt and nut supplied with the brake chambers and cap the air line to the emergency brake side of the brake chamber. This was done in the pouring and bitter cold rain laying under the bus. But I was able to drive to a bus repair shop and the next day the shop replaced my brake chamber.

If you do have a failure of any of the brake chambers while on the road you or a road side service provider can make temporary repairs to get you going again, but I still remember that miserable cold wet day and how unpleasant it was laying on a wet roadside so I could get driving again. I may have had a leak in the emergency brake for quite a while, but in my early days of ownership I didn't do the checks I do now. It's too bad I always had to learn my lessons the hard way.

[phorner]

Jon,

You make a great point regarding the brake test. I know that I get lazy and complacent and don't always perform this test before my driving day as I should.

But it is certainly an important routine to follow.

Thanks for the reminder.....

[Will Garner]

Jon,

Surely you know the hardest lessons in life are the ones that are learned for the rest of your life. BTW, the KOA in Dunn NC has expanded by 80 spaces and I see some pedestals with Jamestown stamped in the case. You know anything about that company?

[Jon Wehrenberg]

I know the president of that company pretty well. We just spent a week with her and her husband pigging out on Cajun food and not talking about business.

[phorner]

I have searched through several YouTube sites and found several videos of CDL air brake test procedures and pre-trip inspections. Most were informative but none really wowed me.

Would it be possible at a future POG rally to capture on video a good pre-trip air brake test that we can then save as a link on the forum? Maybe we could also film the procedure to cage a defective brake chamber as well.

I think this would be beneficial to those members not able to get to a rally, and a video is often much easier to understand (and remember) than the written procedure.

Any thoughts?

[Jon Wehrenberg]

Paul, if the interest is there how about you doing a seminar at Austin on some recommended pre trip inspections. I'm sure we can video it and get it posted. While I think brake checks are important, we cannot overlook the importance of checking lights, tires, fluid levels, belt condition, etc. I also think every pre trip inspection needs to cover the toad because I knew a guy that dragged a Hummer with its brakes on once. (that actually was a pre trip brake test.)

[gmcbuffalo]

Jon when you had that problem were you carrying stands or jacks, or were those the young and foolish days?
GregM

[Jon Wehrenberg]

Young and dumb. Raised it up on the air bags. No jack, no stands, even though I had two jacks on the coach.

For anyone that does experience a failure of an emergency brake diaphragm or hose you can build up air pressure as long as the emergency brakes are applied. But as soon as the brake is released, the air starts to escape again. That is why I had all the air I needed to raise the bus.

[rahangman]

Paul & Jon, this seminar you are mulling over would be great, but even greater (perhaps) would be something to put on the POG so everyone can view it. I would like to be there for a first hands on but may not be. Just my 3cents (inflated) worth

[phorner]

Paul, if the interest is there how about you doing a seminar at Austin on some recommended pre trip inspections. I'm sure we can video it and get it posted. While I think brake checks are important, we cannot overlook the importance of checking lights, tires, fluid levels, belt condition, etc. I also think every pre trip inspection needs to cover the toad because I knew a guy that dragged a Hummer with its brakes on once. (that actually was a pre trip brake test.)

I would be glad to help and I agree that, since the brake test is being demonstrated, the video might as well include a complete pre-trip inspection.

Unfortunately, right now it is uncertain if we will be able to make it to the Rally. Once our plans are firmed up, maybe we can develop something that can be recorded and placed on the forum for the benefit of those not able to attend in person.

[hobobimmer]

[QUOTE=phorner;73651] the video might as well include a complete pre-trip inspection.

Below is the pre-trip checklist Debbie and I use. I think it is straight out of the Prevost Owners Manual (POM) and the Liberty Owners Manual (LOM). Hope this is some helpful. Also hope not any (or too many) mistakes in it.

Eric Faires

PRE-TRIP CHECKLIST

ENGINE OFF
Fire Extinguishers working and accessible. Number of units: at least 3. Located (1) right side front passenger seat on floor, (2) beside bed, passenger side, inside the floor cabinet, and (3) driver side first bay, front wall.
Escape routes planned (all awning/opening windows, plus entrance door, POM 6-2).
Awnings stowed.
Spare keys.
Spare engine belts.
Washer reservoir FULL.
Lighting: verify all exterior.
Tires: check for cuts and proper inflation.
Wheel bearings: check oil level in sight glass.
Leaks: inspect underside.
Coolant: check COLD in sight glass right side of surge tank.
Engine Oil: check.
Air system: purge accessories and wet tanks by opening drain valves.
Power steering: check fluid full.
Fan Gear Box Oil: check fluid level full.
Belts: check wear.
Belt Tension: check visually and check tensioners.
All bays and doors closed and locked.
Adjust driver seat and mirrors.

ENGINE ON
Gauges: check normal.
Warning Lights/Buzzers: check none.
Fuel Level: check adequate.
Transmission: check oil level (POM 7-4). AUTOMATIC TRANSMISSION. Check level TWICE to insure accuracy. Check COLD with engine running, parking brake set, transmission in neutral. Final check HOT when transmission oil at normal operating temp (160 – 250 F) (POM 7-4). Can also check using Tranny Keypad, following instruction on POM 3-22.
Leaks: listen for air.
Water Separator: purge drain valve by ¼ turn on bleed screw.
Turbocharger: look for leaks and listen for unusual sounds.
Service Brakes: check for pressure build up. WITH ENGINE OFF, AND NO BRAKE APPLIED, maximum air loss < 3 PSI/minute. Make full brake application. Loss < 7 PSI.
Parking/Emergency Brake: with air pressure > 70 PSI, apply brakes to lower pressure to insure buzzer/lights work. Air Pressure > 95 PSI before release parking brake. (POM 6-3).


AIR PRESSURE (SECONDARY). Normal Range 95 PSI -125 PSI (POM 3-14).

AIR PRESSURE (PRIMARY). Normal Range 95 – 125 PSI (POM 3-14).

AIR SYSTEM EMERGENCY FILL VALVE. In emergency, can add air via valve in Steering Bay and right side door of engine compartment (POM 6-2).

BRAKE EFFECTIVENESS. Minimum 95 PSI in both Primary and Secondary Air Circuits before driving. DO NOT PUMP BRAKES. Wastes air. Causes unnecessary wear on brake parts. At 70 PSI, warning light and buzzer come on (POM 3-20). If air pressure drops below 40 PSI in normal operation, the spring loaded emergency parking brakes will immediately be applied at full capacity to the drive axle to stop vehicle (POM 6-2).

BUMPER COMPARTMENT (FRONT). POM 1-8.

COOLANT TEMP. Normal Range 190 - 215 F. (POM 3-14).

DIFFERENTIAL OIL TEMP. Normal is DNE ________ F (POM ____________).

EMERGENCY PROCEDURES. Emergency Exits located all awning/opening windows and entrance door (POM 6-1).

ENGINE BLOCK HEATER. Switch operated from House Panel inside bus (POM 5-2).

FIRE EXTINGUISHERS. Located (1) right side front passenger seat on floor, (2) beside bed, passenger side, inside the floor cabinet, and (3) driver side first bay, front wall.

FUEL LEVEL. Do not operate less than 1/8 tank.

IDLE ENGINE. Do NOT operate engine on “low idle” (approx. 550 RPM) for extended periods. For extended idling, run engine at “fast idle” (approx. 1000 RPM) (POM 3-9).

JACKING POINTS. POM 7-12.

LEVEL LOW. Ignition ON (and most times Engine ON). Level rear first (right to left), BEFORE raising or lowering front (POM p. 2-7). After leveling, turn engine OFF and Level Low Knob to DRIVE. To maintain manually leveled position while starting engine (without moving vehicle), move Level Low Knob to any position except DRIVE. When ignition off, return Level Low Knob to DRIVE (POM 3-6).

MESSAGE CENTER DISPLAY. POM 4-1 TO 4-10. Displays/records operational data from DDEC (POM 4-2). Only the following are available when driving: GAUGE MODE, FUEL ECONOMY, AND CLOCK/DISTANCE. Other modes accessible only when stopped (POM 4-3). TRANNY OIL LEVEL diagnostic display mode (POM 3-22). GAUGE MODE shows Tranny Oil Temp, Engine Oil Temp, and Battery Voltage (POM 4-3).

OIL PRESSURE. Normal Range 50 – 70 PSI (POM 3-14).

RPM/TACHOMETER. Maximum RPM 2450 (POM 3-14).

STARTING. Starter Selector Switch in engine compartment set to Normal. Battery Disconnect Switch inside passenger side battery bay door set to “ON” position. Parking Brake SET. Transmission in Neutral. Key to “Start,” then release as soon as engine starts. Run 2 minutes at Low Idle. Then High Idle thereafter while check Oil Pressure (normal 50 – 70 PSI), and other gauges. Five minutes at High Idle WITHOUT load on engine (POM 5-2). Then OK to drive. If won’t start after 15 seconds, allow starter to cool for one (1) minute before re-start attempt. (POM 5-1). No Full Throttle operation until Coolant Temp > 140 F (POM 5-2).

SEAT ADJUSTMENT. POM p. 2-1.

STEEP GRADES. Use lower gears. Do NOT exceed 2450 RPM. Use Tranny Retarder. Keep Service Brakes cool/ready for emergency stopping (POM 4-11).

STEERING WHEEL (TILT). POM 3-20.

STOPPING ENGINE. Parking Brake SET. Tranny Neutral. Low Idle two minutes, allowing Turbo to cool (POM 5-1). Battery Disconnect Switch OFF if stopped for extended periods. Engine shutdown ONLY at Low Idle (POM 5-1).

TACHOMETER/RPM. Maximum RPM 2450 (POM 3-14).

TOWING BUS. First remove drive axle shafts or disconnect drive shaft (POM 7-13).

TRAILER/TOWING. Pulling a trailer over long distances is considered “SEVERE OPERATING CONDITION” and requires more frequent service intervals (POM 1-12).

TRANSMISSION OIL TEMP. Normal Range 160 – 250 F (POM 7-4).

TURBO BOOST PRESSURE. Varies depending on engine RPM and load conditions.

VEHICLE LIFTING. Always raise tag axle before lifting vehicle (POM 4-12). What does this mean? When does it apply?

VOLTMETER. Normal Range 26.5 – 28.0 volts (POM 3-14).

[Jerry Winchester]

Paul,

Are you already crawfishing from the rally? I felt like I needed to spend some quality time with you and you are pulling a (what's the name of that guy from POG 1 who goaded us into the steak dinner then didn't show up?)

[Jon Wehrenberg]

The guy's name was Barclay. If I would have thought quick enough I would have gathered up some of what he was spreading and put it on my tomato plants.

[phorner]

Paul,

Are you already crawfishing from the rally? I felt like I needed to spend some quality time with you and you are pulling a (what's the name of that guy from POG 1 who goaded us into the steak dinner then didn't show up?)

Just sayin' that my accountant is still struggling as we speak to get the check I need to write to the IRS this year under five figures, and this expense may put a crimp in my travel plans this season. :mad:

And I thought I was doing a good thing going back to work BP claims in Mobile last year......

I should have taken the advice of one of my claimants and listed my occupation as a domestic.

Ya see, she explained quite clearly to me (after changing her occupation 5 times) that "domestics don't pay no taxes"

I'll make every effort to be there......:cool:

[truk4u]

Those 1099's are painful!

[rahangman]

Hmmmm tax time "and the living is easy" ain't gonna be that way long....gonna get tough

[Jon Wehrenberg]

More pertinent miscellaneous poop.........

My radiator fan clutch is failing so a new one is on my workbench ready to install. All diagnostics pointed to that so I bit the bullet and spent around $1200 for the new one. But while monkeying around back there I got to realize some of the relays in the rear electric box really get a workout and so far I have not had to replace any of the black cube type relays.

I checked on line and the Potter Brumfield VF4=15H11=S05 best price on line is in the $16.00 range. I checked with Prevost and they have them in stock and they are about $4.75. I bought 10 and will replace the fan clutch relays with new ones because those relays cycle on and off about every few minutes so they have seen a lot of cycles. The rest will go in my spare parts drawer.

At that price they are worth buying and keeping available because the bus uses a couple of dozen of them for various purposes.

[bill lambrecht]

On a IFS XL coach,are the air chambers 30 30/36 16/24 like straight front axle coach?Also I would like to know the air bag numbers for my IFS coach.Numbers on my coach final record are old GOODYEAR numbers(not crossable to firestone)front 1r12-377 rear 1r11089 tag1r11-096 (cant be crossed period).I am going to take the forums advice and replace all the above.My coach is a 1999 VOGUE with 122000 miles. MANY THANKS BILL LAMBRECHT

[Jon Wehrenberg]

Bill,

I don't want to steer you wrong so I will not speculate as to the size brake chambers or air bags on your coach.

I do know this. The guys in Prevost parts (800-799-9938), and Charlie (works second shift) at X114 are a wealth of knowledge and can give you the Prevost numbers as well as the trade numbers and the prices.

I have found nobody that can beat the Prevost price on Air Bags. But the Prevost price on brake chambers is staggering but with the trade number you can shop them at your local truck parts store such as Fleetpride or Truck Pro. The 30-36 and the 16-24 chambers for the rear which I assume you also have are rarely stocked at the local level with the 30-36 readily available.

The 16-24 is almost impossible to find but the Prevost price in the $400 range was easily beaten by buying a 16-24 piggyback and a 16 chamber and assembling your own 16-24 for less than 1/2 the Prevost price.

I can offer specific information if you need it but I have to dig around a little for the specifics.

Your tag axle air bag is likely to be a 630259 and the drive a 630104. that's a guess. I haven't said anything about the front axle because I have no experience with a IFS and don't want to guess. That's why I suggest a call to Prevost.

[Richard Barnes]

I've got the necessary equipment to do the HD video and would be happy to film it. I'd probably need help with the editing.

[Jon Wehrenberg]

Richard, great offer and I think we should take you up on the opportunity to record a good pre-trip inspection. I am trying to find a presenter. Volunteers???

[Richard Barnes]

Just let me know. My home is in Atlanta and just three hours or so from Knoxville. With an outline we could probably shoot this over a weekend. I'll bet Ray Davis could do the editing for us.

[Jon Wehrenberg]

What we would like to do is shoot the pre trip inspection during the seminar.

Between now and the rally I think we will be gathering information and establishing a sequence for the tasks, and the best time to video it will be after whoever will be presenting this has gotten it all together and has practiced it.

There may be differences between conversions so it is possible some interior pre-trip tasks may vary based on the conversion and at the seminar we may have several to video. It might be the interior portion of the pre-trip inspection may be taped and played because there is no way anyone will let a crowd of hundreds go through their coach for the seminar. Outside, yes, but inside, no.

[bill lambrecht]

JON,I called charlie about the air bags.Numbers are 630151 front,630260 rear,630259 tag.Will order from Ft. Worth Prevost.Prices quoted by Charlie are 201.01 front,155.91 rear,137.70 tag.Now my problem is NORGREN valves.My coach has the 5 manifold setup.Part numbers seem very evasive for these valves.Thanks for your help Bill Lambrecht

[Jon Wehrenberg]

Bill,

Prevost uses standard Norgren Valves and has them renumbered with a number that is proprietary for Prevost. Unless Vogue did something unique with the leveling system which I doubt, you will have 5 three port Norgren valves and 3 five port Norgren valves.

I think I have both the Prevost number and the Norgren number but I have to dig a little through my log book to get them, If you want them let me know.

When I deal with the solenoid valves on the five valve manifold (not to be confused with my terminology five port valve) I leave the manifold in place and replace the valve bodies and the coils. These parts are available from Prevost individually or as a complete assembly on the manifold. I think Michael Terry did some checking and ended up buying the entire manifold, but I am not sure why.

Let me know if you want the numbers.

Here comes some preaching........If you are going to change the Norgrens yourself which is not too difficult, do not get under the coach unless you have properly supported it. Don't even think about it because even though there is a risk of the coach coming down anytime you are under a coach, it is guaranteed that it will come down as soon as you loosen an air fitting on these valves.

[Jon Wehrenberg]

More pertinent poop that may be of interest to Liberty owners.

I suggest all Liberty owners do this check so they will understand what might be unique to their coach.

First, turn off the inverters at the remote panel and then proceed to turn off all the house battery switches. With all DC power to the house turned off try to get 120VAC electric power to the circuit breaker panel. If this is standard on all Liberty coaches you will not be able to get 120VAC into the coach through shore or generator power.

So what does this mean? First, it means if you turn off all battery power to the house portion of the coach you have also effectively shut off all 120V power to the coach whether that was your intent or not. But the significance of this is if for any reason you drain your house batteries you cannot use shore power or the generator to power the inverters to charge them up. That means if you are going to leave your coach unattended for an extended period you must completely shut off all house battery switches (making sure the inverters are first turned off) to preserve battery power, or you must be connected to shore power to mainitain the battery charge. I would be reluctant to depend on auto-start unless I had total confidence in it because a dead set of house batteries can become a big deal.

I learned this on my coach soon after I got it, and was reminded of this again recently by a POG member who had his batteries go dead after his coach had to spend two weeks at a service facility.

One point that needs to be understood. The chassis batteries will not be affected, but even if you can start the engine the alternator for the house on a 12 volt coach (a 24 volt coach will be OK) will not charge dead batteries until they first get a charge and are carrying enough voltage to excite the field on the alternator. The reason the 24 volt coaches are able to charge house batteries is because the chassis batteries will supply the voltage to excite the field on the 50DN alternator and the house batteries will get charged back up. However, according to our resident Lifeline guru Truk, the proper way to charge a dead set of Lifelines is to slow charge to about 8 volts and then hit them with a high current charge. The typical 50DN alternator is going to put out as much as 270 amps which is a real big charge rate so relying on that to recharge dead batteries may not be the best thing to do.

So my advice to Liberty owners is to shut down the DC power to the house to find out if it does prevent 120VAC from getting to the electric panel, and if it does develop a game plan for how you will recharge a dead set of house batteries. Charging them slowly using booster cables and the car might be an option to consider.

[truk4u]

For Liberty owners, Jon's post is a must know item in my opinion. You could also lose DC power by some other means such as a breaker or a switch and your faced with the same situation, no 120VAC.

It would be good to know just how Liberty ties the two sources together and what device they use to prevent 120VAC without DC voltage.

[rahangman]

What say Thee, Mr Truk, do you have an opinion or thought on CC situations such as this. I am slowly learning these days about my 120vac system (no auto start) and routing issues on mine. Just thought I would ask.

[truk4u]

Beats me Roger, I'm going to experiment with the Royale and see if the same thing happens. Pretty easy to figure out, take off all DC power and see if the 120VAC is still alive. Maybe someone else already knows this.
Try it on your CC and let us know.

[gmcbuffalo]

I have Beaver Conversion and during my battery change out found out that I have the same problem. I thought that the problem was the transfer switch fails to work if there is no DC voltage. Or this problem could be related to the Allen Bradley computer not functioning without DCV. During the 90's Beaver and CC did a lot of things the same, Spies in every shop.
Greg

[garyde]

I will check with Troy at Liberty. My thoughts are similar to greg's, that the control circuit for the transfer switch is controlled by the inverters. My Allen Bradley has a seperate small battery which I have not changed out and is probably no good. I keep my coach plugged in all of the time, but if I have a Utility outage , which occurs several times a year, it puts my house batteries at risk.

[LNDYCHT]

I am sure I will catch some flak but here goes.

The digital AC volt meters are powered by DC voltage, this is the only way that a digital AC volt meter will read 000 volts. So if you have no DC voltage the meters will not work.

Many inverters will not charge dead batteries. Many inverters will not transfer AC voltage without DC voltage present as they use the DC voltage to activate the transfer relay, also they don't want to try and charge a battery that is not present as this will damage the transformer. If you turn off the inverter input you will have no output on the transfer portion of the panel.

The generator and shore power transfer switches are AC actuated.

This may not apply to all coaches, but with no inverters ( I just removed mine) and no DC power ( batteries disconnected) I have no voltage on the digital voltmeters but all AC circuits that do not run through the inverter's work ( air conditioning, electric heat, hot water etc).

[Jon Wehrenberg]

I hope everyone understands this loss of ability to get AC power to the house when there is no DC power has nothing to do with inverters.

When the house battery switches are off or the batteries are dead you cannot get 120VAC to ANY 120V circuit.

If you want to prove this, turn off the inverters and all power to the inverters. You can still get 120VAC power to air conditioners and other 120VAC circuits except those supplied through the inverters.

[gmcbuffalo]

Jon I can not get any power to ac circuits without DCV, my coach is completely dead.

Due the Allen Bradley computers have coin cell batteries and if so where are they and how do you change them?

Greg

[Jon Wehrenberg]

Greg,

I am unfamiliar with the Beaver, but on my coach the Allen Bradley PLCs have a back up battery that has to be changed every two years. It is not a small battery but about 1 X 2 X 4 and it is intended to provide power to the PLCs so the generator can be started.

[gmcbuffalo]

I'll look around. I do know I have a power source to them from the house batteries.

[Jon Wehrenberg]

I am surprised your vintage coach has PLCs or the equivalent. If it does, as any coach with them some form of emergency power is required to enable basic functions so the coach can be brought alive in the event of total failure of the house batteries.

Rule #1 has to be to always be assured house (and chassis) batteries are prevented from totally going dead. It is just a hassle restoring power to them.

[garyde]

Hi Greg. If you don't have one, I would go out and purchase a small battery capable of running your AB system.