Wiring Woes? Diagrams Defuse Difficulties

It wasn't but a few minutes after we'd been doing a little roof work on our "camper project," that another problem surfaced: All the fluorescent lights and the bathroom light "quit" working. What happened here, let's see. Ah, yes! The luggage rack seemed a little wobbly, as did the roof access ladder, and a new set of lag screws had been introduced to try and shore up the situation. Did one of those new screws sabotage the circuit? (Word freaks, stick around, we'll discuss that old origin of "sabotage" question at the end of this entry).

Poking around in the fuse panel revealed a definitely "blown" fuse, but was this the whole story? If only we knew just where the wires ran, it would make the whole job of trying to resurrect the lights much easier. Since the rig is an "orphan," -- it's manufacturer having gone out of the camper business long ago, we despaired. However, a Google search led us to others who had success in finding diagrams for their more current rigs. Hence, we took courage and phoned phleetwood. A sympathetic listener at the other end of the line took the request, even called back later asking for a VIN number, and next morning, hot off the e-mail, a five page wiring schematic for our out-of-production rig.

Long story short department: It didn't take long to figure out a pretty likely "point of impact" for our errant lag screw. We'll attack the roof shortly, and armed with the schematics, if worse comes to worse, we may have a hand on a "work around" solution if it comes to that. Moral of the story: Even if your rig is out of production, if the company still exists, give them a call and ask about the possibility of getting schematics. They may even give them to your for free!

And a word about sabotage: Star Trek fans, while it's a popular notion that throwing sabots (French for clog) into powered looms could "clog up the works," there doesn't appear to be any credible report of such a sandal scandal. More likely, since the word sabot can also be reckoned as a literal clog, the sound made by someone clunking around in clogs leads to the word, saboter. Such walking was oft associated with clumsiness, and later extended to deliberate clumsiness that damaged machinery.

Photo: Looks like the tech writer after a bad day searching for shorts. Credit DerrickT on flickr.com

RV Extension Cord Safety

Ever come up just a "scoatch" short on managing to plug your RV shore power cord into the outlet? It's a frustrating experience, and there's always the temptation to use an adapter and a light duty extension cord to make up the difference. Please don't. Electricity is a funny thing--when too "light" a wiring is used, not only do you endanger yourself with fire, you also run a good risk for your expensive RV equipment.

Here's the deal: Electrical wiring actually does have a certain amount of resistance to the flow of electrical current. The longer the run of wire, the greater the amount of resistance. As the current struggles against this resistance, it produces heat energy--hence electrical cables can actually get hot--sometimes hot enough to create that hideous problem known as fire. What usually "goes first," however is the under-rated fittings on the end of the cables. These can overheat and burn up, or on the way to that create even greater resistance to electrical flow. But even if that doesn't occur, the resistance of the wiring actually reduces the amount of voltage that can reach your RV.

So if you have too small an extension cord out to the RV, and then fire up a big power consumer--on these days we think of the air conditioner, and not enough voltage is present, then physical damage can happen to devices that need that power. So how do you work with this problem? Well, you could purchase a ready-made RV extension cord. For the 30 amp RV crowd, a 25 foot cord will probably set you back as much as $50. For the 50-amp users, that same length could run you over twice that price.

Tempted to "do it yourself," and build an extension cord? It's do-able. But you need good working data on what size conductors to use in your cord. Here's a link to a site that can help you calculate wire size requirements for a given load. But as you run your calculations, be sure to take into account the length of your existing RV shore power cord. One of our rigs has a 25' shore power cord, so building an additional 25' of extension cord would require figuring a full 50' run. Whatever you do, don't skimp on the wire gauge or the fittings.

If you decide to build your own, always double check your connections before putting your cord into service. We use the ohm meter portion of a digital multimeter to verify that everything it where it should be. Imagine our surprise when we completed a cable and we found two of the conductors reversed. How'd that happen? Squinting through bifocals at the included wiring diagram for one of the fittings, a slight misinterpretation of what the fine print and finer arrow we're pointing to led to what could have been a real problem.

If you're the least bit squeamish about your ability, drop the bucks on a commercially built unit.

And one more thing, when you use any shore power cord, it's never a bad idea to pull all the shore power cable out of the compartment before hooking up and using the shore power. Why? Well, since cable does have resistance, if you put enough load on your shore power cord, you could actually have the equivalent of a "heating cable" in your cabinet--like those things those poor folks in the north use to keep their pipes from freezing in winter.

Charging Batteries Safely

A news item out of Yuma, Arizona, last month points to a couple of reminders--and a product lead--that could affect your safety as an RVer.

Imagine waking up at one in the morning with your smoke detector going off, and that awful sound of a roaring fire outside your bedroom door. It happened in mid-June to a Yuma couple, who were planning an outing with their motorhome. Apparently having a low battery problem with the motorhome, the owner had hooked up a battery charger and left it. Sadly, the battery overcharged, and the resulting heat ignited a fire. In the end the motorhome and the family home were completely wiped out. You can find the whole story on the Yuma Sun website.

We've been around battery chargers since we were 'knee high to a married grasshopper' and some of the "oldy" chargers that our pappy's owned were probably hanging around when they were knee-highs themselves. It just seems like battery chargers are one of those products that rarely give up and die. As a result, many of us are limping along on ancient technology that may work--albeit inefficiently--but can (as it apparently did this time) lead to tragedy.

A lot of us use portable battery chargers, and many of these fall into the category of what's technically called an "unregulated charger." Hook it up, the charger delivers a charging voltage (higher than the "rated" voltage of the battery) and just keeps a charging. The battery voltage increases as it charges up, and it will eventually reach a point where the electrolyte will literally boil. An unregulated charger needs to be monitored. Yes, with this type of charging system, you would want to occasionally hit the boiling point to "equalize" the charge in the cells. However, if you "cook" them too long, you'll kill the battery, or even worse--lead to a fire danger.

A complete discussion of battery charging is an appropriate topic--and we'll cover it in a future blog entry. Now, however, we make this point: For many it's simply safer, and far more efficient, to use what is termed an "intelligent charger." An intelligent charger recognizes the state of the battery's charge, and supplies exactly what is required at any given stage in the recharge process. Enter the Xtreme Charge maintenance charger. A relatively inexpensive ($99 list) charger, Xtreme is an "intelligent charger" that also adds an additional benefit: This charger "pulse charges," inducing a wave into the charging current that breaks up sulfate crystals in batteries. These sulfate crystals, if left to themselves, will eventually kill off an otherwise good battery. The Xtreme can be left hooked up to the battery, and it will maintain a safe current level, along with the sulfate-eradicating pulse.

Xtreme's manufacturer sent us an evaluation unit a couple of months ago. While we're still testing it, so far we've been pleased with it. It's a small unit that can fit in many battery compartments, and even if it won't it's weather proof, so you don't need to worry about a passing rain shower shorting out your system. While the specs indicate the Xtreme is designed for battery systems up to 150 amp-hours, the company whiz-kids tell me that it will work with larger systems, but its relatively low (2.5 amp) maximum charge current will take a while. Amen to that. For a larger system, consider the Xtreme a good investment in battery maintenance, rather than full-scale charging. Find out more at the Pulsetech website.

There are also "intelligent charging" systems available on many after-market (and some OEM) RV converters--those little devices that convert shore power into low-voltage power, suitable for use by RV interior lighting and other uses. In any event, when you hook up a charging system to your RV batteries, make sure you keep an appropriate watch on it--particularly if it's an unregulated charger.

Fire Photo: Yuma Sun Charger: pulsetech.com