RV Doctor Column RV Doctor #282 Dear Gary, The house batteries on our RV are the original ones, purchased new with the RV in August, 1995. They seem to be working well except that in cold weather they cannot keep the furnace fan going all night. Automotive starting batteries last about five years and ours has been replaced. How can I test the deep-cycle batteries to see whether they should be replaced? When the time comes, would it be better replacing the two deep-cycle batteries with golf cart batteries? I have the space. Frank Winter, (Manalapan, NJ) Indeed Frank, it is best to use two 6-volt golf cart deep cycle batteries in place of a single 12-volt battery. If you have a lot of room, consider four 6-volt batteries wired in a series/parallel configuration. Two of the 6-volt batteries are wired in series, and the other two are wired in series, then the two sets of six are wired in parallel. This will give you plenty of current storage. Chances are your batteries are quite sulfated after so many years. You've been very fortunate to have them last this long. To be sure, the batteries will have to undergo a carbon pile load test. Any full-service RV shop will have a decent carbon pile tester. A carbon pile test will reveal just how sulfated the plates are and if it necessary to replace the batteries now. Always replace all of the batteries that will be in that circuit. For optimum results, keep them all batteries the same type, the same size and the same age. Dear RV Doctor, I have a 2500 watt gasoline generator that is designed to connect to a household electrical outlet for power outages in storms or whatever. Can I put it in my 5th wheel trailer and connect it to my electrical cord as I would a campsite hookup? If so will I need a better muffler as it seems pretty loud? Do you see any problems here? Doug Roberts, (Pacific Grove, CA) Doug, Noisy as they are, portable auxiliary power generators are okay to use with an RV as long as the ground and the neutral are separated in the output section of the generator. This is important since all RVs have an isolated neutral; meaning there is a separate buss for the neutral side of the alternating current electricity. It is also recommended to bond the generator to the frame of the trailer with an 8-gauge or larger conductor. It is not recommend, however, to alter the exhaust components on any generator. Increasing the back-pressure could damage the engine portion or otherwise shorten its life. On second thought, if you were parked next to me in the campground, I think I would opt for the shortest life possible for your generator. Be sure to use the correct adapter plug and always plug the shoreline cord of the fifth-wheel into the generator; never connect the output of the generator into one of the 120-volt outlets inside the RV. Do not place the generator inside any compartment on the trailer and be sure to keep it safely away from window and door openings. Dear Gary, I read a lot of articles on how to maintain rubber roofs, but I do not find anything on what needs to be done to maintain a metal roof. What are the things that need to be done to maintain a metal roof? Thanks. Joe Wilson, (Troy, TN) Joe, Very good question; many believe it is easier to maintain a metal roof, though those same people extol the benefits and ease of EPDM rubber also. There must first be an understanding of how the metal roof is constructed. Earlier and lower priced RVs often had a soft roof composed of batts of fiberglass insulation positioned between wood rafters and covered simply by a continuous length of rolled roofing metal typically made of aluminum and having seams every few feet. This was the most common method of roof construction, adopted from the early mobile home industry. The drawback to this method is that you could not safely walk on or otherwise use the roof area. Damage to the roof was common especially when a technician walked between the rafters thereby stretching the aluminum at its seams or possibly even puncturing or tearing the soft aluminum causing leaks. Installing components such as TV antennas, roof racks or storage pods was also difficult at best. When working on a soft roof it is always necessary to use wide walking boards long enough to straddle at least three different rafters at the same time in order to distribute your weight enough so as not to damage the seams while working up there. Then someone got the bright idea to add a layer of plywood across the wooden rafters before rolling out the roofing material; the hard roof was born. I'm not sure who the first manufacturer was that utilized the hard roof but all owners and repair persons since truly owe a debt of gratitude to them. Though the roofing material was basically the same, the plywood substrate now made it easier and safer to walk on the roof, install components and perform the necessary maintenance. Also adopted from the mobile home industry was the basic color of the roof. At first, the aluminum was simply aluminum-colored or silver. Cheaper to manufacturer, but not as adept at reflecting the sun's rays as a white roof. So, many owners completely covered their aluminum roofs with a reflective, white coating. Then producers actually manufactured the roofing rolls in white which became a valid selling point for dealers. The RV roof has seen many innovations over the years including steel and aluminum framing members, Styrofoam insulation, vacuum-bonded, one-piece laminated roof sections, etc. But the aluminum roof still lives on through all the changes and there are many older coaches out there with impeccably maintained metal roofs that have never leaked. The secret? Frequent inspections and yearly maintenance. Many rolled roofs are made with interlocking sections using cleats or special seams that allow many sections to be joined and then rolled out in seemingly one piece. Other roofs are just simply one piece of aluminum. But remember, any component attached to the roof; 14-inch vents, sewer caps, refrigerator vent, TV antenna, air conditioner, etc., must also be properly sealed. Any attaching screw in or on the roof is a potential leak waiting to happen. All it takes is time and lack of attention and virtually every roof will, at some point, begin to leak moisture. And realize there is a difference between roof coating and a roof sealant. The coating, remember, was used to effectively insulate the interior by reflecting the sun's rays. Roof coating is not a viable, stand-alone roof sealant. Moisture can still enter an opening that may be coated and not sealed. Here's what I recommend as soon as you take the RV out of storage. First, carefully clean the roof area completely. Wash all dirt and debris from the entire roof. Take care, wet roofs are quite slippery! Next, carefully inspect each seam, front and rear caps and around each component on the roof. If there are any visible signs of cracking in a seam or around any screw head, etc., apply a sealant to plug the opening. Tube silicone is effective in some of these instances. A coating can then be applied over the sealant. I recommend using white coating to aid in reflection. If, on a soft roof, a seam has cracked opened over a considerable distance, use a piece of fabric webbing along with the sealant. Apply a layer of the sealant, then embed the fabric webbing into this layer. Finally, add another layer of sealant to smooth out the webbing. Apply enough so that it fully covers it. Be sure to feather the edges away from the fabric. The best scenario is to have the sealant and coating remain flexible as the roof expands and contracts with the weather. By keeping the roof clean and immediately making repairs when something is found amiss, a metal roof should last many years.
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