Some Battery Basics
Dear RV Doctor:
I am getting ready to purchase new batteries for my coach. I remember you saying in your seminar that it is possible to determine the amp-hour rating for any battery by dividing the cold cranking amps by 5.75. If that is the case, then why would I want to pay extra for RV/marine or deep-cycle batteries if they have the same amp-hour rating as a regular 12-volt battery? Is the deep-cycle battery better, or is this just a sales gimmick?
Guy
Via e-mail
Guy, I think you’re confusing amp-hour ratings of like-sized batteries with the different types of battery technologies. Regardless of the amp-hour capacity, it’s important to recognize the primary differences between a “regular” 12-volt automotive battery and a deep-cycle battery. They are intended for two completely different purposes.
The automotive battery is designed to deliver a high rate of DC current (amperage), but for a short duration, such as when starting the motorhome engine. Conversely, deep-cycle batteries provide a relatively low amount of current, but over an extended period of time. Using either type in the wrong application will likely shorten its life and perhaps ruin a perfectly good battery. Since all loads in the coach typically require low amounts of current, it’s best to have true deep-cycle batteries in the battery bank. Commercial-grade, deep-cycle batteries can be discharged and recharged many times over. Not so when an automotive battery is used in a deep-cycle application.
By the way, I consider the RV/marine type of battery to be a hybrid of sorts, and I recommend it only for the casual RVer. That type comes the closest to performing both applications, though. For serious coach owners, however, especially those prone to dry-camping excursions, it’s always best to utilize the technology of true, deep-cycle batteries. Since my prevailing philosophy regarding motorhome batteries is that you simply cannot have too much DC storage capacity, always carry as many batteries as you have space for (considering the additional weight), and that your wallet can endure.
Humidity: It’s All Relative
Dear RV Doctor:
Hey, Doc! We are currently volunteering in Newport, Oregon, and are trying to keep on top of the humidity in our motorhome. Most of what I have read says we should keep it between 30 percent and 50 percent, but that has the dehumidifier running constantly. The humidistat on the coach rarely reads below 50 percent, and we are pulling very little water out of the air now. The windows are staying fog- and moisture-free, as are all of the surfaces, but I have noticed that the floor is starting to “creak.”
I ran across an article published by the National Park Service that says, “If you have employed the use of extensive fine wood flooring, paneling, trim, cabinets, and furniture in your boat or RV interior, you will want to keep your humidity levels between 50 percent relative humidity and 60 percent. At levels lower than 50 percent, woodwork may become dried out.” In your learned opinion, what would be a good setting? Relatively speaking, that is!
Ken Himes, F430226
Newport, Oregon
Great motorhome question, Ken! Here’s my non-RV (but hopefully helpful) response. I would consider the optimum relative humidity level for motorhome interiors in the same vein as I do for my acoustic guitars: between 45 percent and 55 percent, which kind of echoes the information from the park service. Certain circumstances, such as the inclusion of fine wood flooring or cabinetry, may perhaps mandate a slightly wetter setting, depending on the materials used. That creaking floor definitely indicates a “too dry” situation. All I know for sure is that my guitars, also here in the Northwest, seem happy in that environment. By the way, I am currently testing a reusable (non-powered) dehumidifier called the H2Out. I haven’t reached any conclusions yet, though.
Time To Re-Tire
Dear RV Doctor:
While looking online and trying to decide what tires to buy for my motorhome — a 31-footer on a Workhorse chassis — I realized I need all the help I can get. I’m trying to smooth out the ride. I have jotted down all of your tricks on motorhome suspension products and will follow that advice to the T. If you were to spend your own money on tires for my motorhome, what tires would you get?
Greg Johnson
Via E-Mail
Reading your question carefully, Greg, unless I win the lottery, it’s quite doubtful I’d ever spend my money to purchase tires for your motorhome! But your point is understood, my smart-alecky retort notwithstanding. Walter Cannon, executive director at the Recreation Vehicle Safety & Education Foundation (www.rvsafety.com), and I both claim no favorite front-runner as far as individual manufacturers. But we both suggest you stick with the mainstream brands and be sure that the tires match the demands of the weight they will be supporting.
We first recommend that you have the motorhome weighed while fully loaded for travel, using individual tire scales. This will not only answer the weight question but also will determine how much air pressure is required to support that weight. The tire retailer can advise you which tread design might be best for a smoother or quieter ride. Michelin, Firestone, Goodyear, etc., all can be considered. Obviously, special deals and “sale” prices may sway you one way or the other, but as long as the tires have the proper specifications for your motorhome, you’ll be fine with any of the major brands.
I’d purchase and mount the tires first, before resorting to any of the aftermarket products I may have mentioned. You just may find it unnecessary to add more equipment once the tires are replaced.
Editor’s note: FMCA members may find advantageous pricing on Michelin RV tires through the FMCA Michelin Advantage Program. Visit FMCA.com or call the FMCA national office at (513) 474-3622 or (800) 543-3622 for details.