By Gary Bunzer
June 2005
Generator Point Gap
Dear RV Doctor:
I was asked a question the other day by a fellow RVer about a 4,500-watt Onan generator. He wanted to know if I could find out what the point gap of the points on his unit should be. Numbers are no longer visible on the plate of the unit. He has a 1988 motorhome and cannot find the information anywhere. I have searched all over the Internet for this information; however, generator numbers are needed to look it up. My generator has electronic ignition so I cannot give him the information from my manual.
Dave Farrell
Enfield, Connecticut
RV Doctor: Dave, I’ve searched my technical library and I cannot find a 4.5-kw Onan from that time frame, though I could be mistaken. They did produce a 4.0 and a 5.0 at that time, each using a different engine. To the best of my knowledge, the correct gap with the points full open (TDC) should measure 0.020-inch for all engines of that era. To be sure, a quick call to any Onan distributor should confirm this. With a description of the engine and any other markings still on the unit, the distributor should be able to positively identify which engine is coupled to that generator.
Conniving Convertor
Dear RV Doctor:
I have an 18-month-old motorhome, which I store inside a metal building. It sat for about six months, and when I went to use it, the battery was dead. When I pulled the caps to inspect it, the battery looked as though it had been boiled to death from overcharging. I usually leave it plugged in, thinking the charger will stop charging. I have a convertor in the coach. Did I damage the charger by leaving it plugged in all the time? Would I be better off disabling the convertor and buying an external charger designed to be plugged in all the time, like the one on my boat? Should I just charge the battery a couple of days before a trip? I thought you should keep the battery charged. Is this correct on deep-cycle batteries? Is there a way to check where the problem might be with the charger? All fuses that I can find are good, and no breakers are flipped except the water heater, which I leave off unless we are camping.
Paul Kothe
Waco, Texas
RV Doctor: Paul, there are differing views concerning leaving the RV hooked up to constant shore power, as well as a plethora of misconceptions that attempt to validate each view. It is my opinion that a lot depends on the type of convertor/charger your motorhome has. For a generic, stock answer, I usually recommend not leaving the coach plugged in unless you are available to check on the battery system continually, especially if your batteries are of the standard wet-cell, lead-acid type. The typical run-of-the-mill convertor/charger has the propensity to overcharge the batteries when energized full-time. Most continue to charge well past the relative gassing voltage, thereby shortening the life of the batteries and creating a hazardous situation.
Today sophisticated, multistep convertor/chargers are available that do allow unsupervised, continuous connection to the shore power. But older chargers simply did not have the technology available to allow multiple charging algorithms. Some had a “trickle” charging feature, but overcharging still can occur at any current rating once the battery voltage has reached 14.3 volts DC.
In addition, the availability of absorbed glass mat (AGM) batteries has increased the RVer’s electrical hope. Because AGM battery technology permits more positive plate material to be saturated by the absorbed mats in each cell, there is an automatic increase in the battery’s capacity in virtually every area. More life cycles, reduced internal resistances, higher amp-hour rating, more reserve capacity, and deeper depth-of-discharge cycles are some of the improvements over other types of lead-acid batteries. AGM batteries are less susceptible to damage caused by overcharging, but unless your coach is equipped with a multistage “smart charger,” or unless you are readily available to check the specific gravity every four hours or so, I would not recommend leaving the unit plugged in all the time.
A highly recommended, though somewhat costly, upgrade includes AGM batteries coupled with a multistage charging convertor. The configuration I favor leaves the existing convertor in place as the actual convertor with the new multistage smart charger installed solely as the battery charger “” costly, but optimum.
Soggy Safari
Dear RV Doctor:
We live in our 37-foot Safari full-time, just north of Sacramento, California, but haven’t driven it much over this past winter. As you know, we’ve received much more rain this winter than usual. As a result, the inside of the coach has been “flooded” with condensation. We wipe the windows and everything we can think of. We’ve even tried drying chemicals, which really bother my eyes “” but we still get water on the ceiling, in the cabinets, etc. Plus we’re afraid of mold. We have two roof vents and covers for them, but my husband has been too busy on the few dry days we’ve had to install them. And we have awnings over the windows. What can we do?
Kathy Sowell
Grass Valley, California
RV Doctor: Kathy, condensation is one of those RVing facts of life that, unfortunately, can never be totally eliminated, only minimized. It has to do mainly with the construction and insulation limitations of the RV design (thin walls and lots of windows). Though some RVs are better insulated than others, some degree of condensation is inevitable, since the air inside the RV is almost always warmer than the air outside, especially during the winter months. Here are a couple of methods you can employ to keep condensation to a minimum.
The first thing to do is to get those vent covers installed even if you must take your Safari to an RV service facility. During use, keep the rear-most roof vent opened and the forward-most window cracked open slightly. The process of convection will move much of the moist air out. This air movement can be aided with the addition of a small electric fan or with the air conditioner fan when the coach is connected to shore power. A small, portable dehumidifier or two may help as well, but, again, they should be used only when 120-volt-AC power is available. Finally, on those chilly, rainy nights, set the furnace to a lower temperature. Combined, these methods will help reduce your moisture problem and further prevent the formation of mold.