House Calls with the RV Doctor
By Gary Bunzer
Dear RV Doctor:
I have a three-burner propane stove in my RV that seems to take longer and longer to perk a pot of coffee. I recently took a trip in a friend’s RV and noticed his propane stove perked coffee much faster. On inspection, I noticed the flames on his burner were about 1 inch tall and were a nice two-tone blue. On my stove, while the flames are blue, they are only about 1/2-inch long. Is there something wrong with my burners? My incoming line? The tanks show a constant 150 pounds pressure with no leaks. Do newer burners burn hotter?
RV Doctor: Dan, indeed the design of the burner head itself has a lot to do with the structure of the flame emitting from each port, but the Btu rating of each burner is determined by the orifice size at the burner valve itself. The larger the orifice, the more LP is allowed to pass through and into the mixing tube. In today’s RV stovetop, the mixing of air with the incoming LP is usually nonadjustable, so the only variance in the equation would be the delivery pressure of the LP. It is important to have the delivery line pressure checked annually at the very least. It should measure 11 inches of water column, which is a very small amount of pressure. Eleven inches of water column equals four-tenths of one pound per square inch (0.4 psi). I’m guessing your LP pressure is lower than normal. That, coupled perhaps with an obstruction at the burner head itself, will result in a much smaller visible flame at the burner head. It’s time to have the pressure adjusted, or at least checked. Because the LP pressure is relatively slight, it can be adjusted only while monitoring and measuring with a manometer. Never attempt to adjust the pressure without using a manometer. Unless you’ve had specific training in the use of a manometer, I suggest you make an appointment at your local RV service facility. It’s a quick and easy job to measure and adjust the LP pressure and, at the same time, check the entire coach for LP leaks.
Dear RV Doctor:
My parents have a 1990 Cobra type A motorhome with a problem. Something is going on between the alternator and the chassis battery; the battery will not hold a charge. If you use the wipers or headlights or anything like that while driving, you lose battery power until the whole thing dies. They have replaced the alternator, the battery, and (I believe) the inverter, yet the problem persists. Currently the whole thing is rigged with a battery charger that is hooked into the generator. Any thoughts on what else could be causing the problem?
RV Doctor: Kelly, battery problems seem to ever nag us. The first step in finding out why batteries seemingly discharge quickly is to analyze the battery itself. Severely sulfated batteries simply will not hold a charge compared to newer, fresher batteries. The degree of sulfation is proportionate to its ability to hold a charge. All batteries self-discharge, but sulfated plates quicken the rate. Find a shop in your area that has a carbon-pile battery load tester. This test will provide insight into the internal happenings of the battery. Clean and tight electrical connections are also extremely important. Corrosive terminals and faulty butt splices and other connections all lead to early capacity loss.
Also, determine whether the battery has indeed been fully charged. Chances are the battery has not been given a chance to become completely charged. Motorhomes of that vintage are notorious for employing mediocre or even inadequate charging systems, including an undersized alternator. (A fully charged battery is one that, during an independent charging process, maximizes the specific gravity reading and then plateaus. In other words, the specific gravity refuses to rise any higher. After two hours in that state, the battery is then considered fully charged.)
After the battery has been tested, focus on the alternator itself. Alternators and convertor/chargers back then did not have the technical algorithms available today for proper and complete automatic battery charging.
Tests should also be performed on the individual battery circuits to determine whether any drains exist. Some small, parasitic drains are normal, but when current leakages approach 700 to 800 milliamps, something needs to be rectified. Obviously, a larger drain on a battery is even worse. A qualified professional RV technician can easily perform this test for you.
There is good news, however. Today’s aftermarket alternators and convertor/chargers increase the RVer’s ability to extend the electrical life in the batteries. Also, newer battery technology has improved battery performance and has minimized over-charging risks. It should be a consideration for all serious owners of older coaches to upgrade to high-tech batteries, sophisticated three-step chargers, and high-output automotive alternators. Electrical woes will certainly be minimized and, under proper usage, can be completely eliminated.
A/C On Gen
Dear RV Doctor:
Recently I was hooked up to shore power that had issues, so I switched over to my generator. At one time the generator powered both roof air conditioners, but now it only runs one at a time, just like when I’m on regular 30-amp service. Could it be something in the power system?
RV Doctor: Merle, I know you are aware, but I want to remind our other readers that your coach was factory wired for two installed roof air conditioners, but because the shoreline cord is only rated for 30 amps, you are only able to run one roof A/C at a time. Remember, each air conditioner must be on its own 20-amp circuit. There should also be a switch inside (some are automatic, others manual) that allows you to choose which air conditioner to run while plugged into shoreline power. Running both units off the shoreline, as equipped from the factory, is mathematically and electrically not possible, hence the need for some type of switch.
The generator, however, adds another dynamic to the mix. It is rated to power both roof air conditioners at the same time – it has enough output capacity. Typically, the rear air conditioner is hard-wired directly to the generator output. On or near the side of the control box on the generator, you’ll find two circuit breakers; one is wired directly to one of the roof A/Cs, and the other breaker is wired to the coach distribution panelboard that protects all the other 120-volt circuits in the coach, including the other A/C. Chances are the circuit breaker on the generator itself is tripped or faulty. And there is the outside chance the air-conditioner breaker in the panelboard distribution box is faulty.