Electrical Diagnostics

These are the main things you should have in your minivan camper conversion to test your electrical systems, and make sure you are protected any time you plug into power, but they are also things to use and keep in mind when RV’ing or camping, no matter how you do it.

12-volt Tester

This is undoubtedly the simplest item in your tool box. Usually it will be nothing more than a small screwdriver shaped device with a clear handle and a bulb in it. In place of a screwdriver blade will be a sharp point. On the back of the handle will be a wire with an alligator clip on the end of it.  All you have to do is clip the alligator clip to a grounded metal surface and touch the tip of the pointer to a suspected hot terminal or wire. If you get a light, then you know it’s got power to it.

12-volt Meter

Besides telling you whether you have power to something, a meter can tell you how much power, either in voltage or amps being drawn through the circuit. Keep in mind, you can have voltage, but if it isn’t being used, then you have no current being drawn in the circuit (no amps).  You can also measure the resistance of something, such as a light bulb or an actual resistor. Many things have resistance that is important to know, even spark plug wires. Without an accurate way to measure such resistance it’s hard to know whether there is a problem with the item being tested. Sometimes you can detect voltage through a circuit with a small load, but it goes away with larger loads applied to it. That can indicate that there is a bad connection somewhere that is only letting part of the voltage through it, and a meter can tell you whether there is a voltage drop and how much. By tracing the problem back through the circuit, you can tell where the problem is occuring.

Meters come in all kinds of styles. The main kind that you should have in your vehicle for troubleshooting is a general purpose meter, either analog meter type or with a digital display. It should be able to test for voltage in AC and DC up to 250 volts (in case you have to check a park power post for problems), and it should be able to check resistance, from zero to about 200K ohms. Typically you aren’t going to check for current draw on DC circuits that much, so that feature isn’t as important, and most small meters have to be “inline” in the circuit to do it, anyway. However, checking for AC current draw can be quite useful to see what your total load is on a circuit.  For that we use a device called an amprobe, which is a meter with a clamp-like device, or jaws on the end of it. We press a button to open the jaws and let them close around the wire. Keep in mind, it will only read one wire at a time, so don’t try to clamp it around a cable with multiple wires in it. You have to be able to use it a point wheer you can get to one wire at a time or else have a way of separating them. This is a task better left to an electrician, since it usually involves testing wiring while it is energized. If in doubt, call an expert!

12-volt Plug-in Meter

This is a handy device to have on hand as it simply plugs into any 12-volt cigarette lighter socket and gives you an immediate readout of the voltage there… no buttons to push, no switches to flip. As soon as you plug it in, the voltage will activate it. I’m not really fond of the ones that just have lights on them. I think they are over simplified. I like to see an analog  meter, where you can see the hand move.

Most of the better ones have at least three scales on them, marked with green bars.  One is the normal, “dormant” voltage, with nothing happening. The second will be a scale with all the devices on vehicle turned on… lights radio, dome lights, etc, to see if there is any significant voltage drop. There shouldn’t be much…usually no more than a one volt drop.  The third scale is used when the starter kicks in.  Your starter is the highest power consumption device on your vehicle. If you have a battery going bad, sometimes small loads won’t affect the battery too much, but if the starter pulls the meter (and voltage) down below acceptable levels, then you may need a better charge put into the battery, or a new battery. Some meters have a fourth scale at the upper end to indicate what kind of voltage you are getting with the engine running. It should read about 13.8 to 14 volts. Even though the battery is rated 12 volts, charging systems always run a little high, to “push” the voltage into the battery. Too little and you will notice lights getting dim and charging not working properly. You may have a bad alternator or regulator. If too high, it could be a bad regulator that is not controlling the voltage properly. When too much voltage is put into the battery it can boil the water in the battery and cause it go bad before very long.

12-volt Battery Load tester

This is sort of an “optional” tester. If you even suspect that the battery may not be holding a charge when everything else seems good, you should check it with a load on it. Your plug-in meter will give you a good indication of there’s too much voltage drop with the starter engaged, but this is a better way.  The internal resistance of the battery could be bad. Once that happens, it’s time to trade it in. Most mechanics will check this for you free of charge of they think they can sell a battery. The trick is that it has to be checked with a fully charged battery, so they may ask you to wait while they charge it for awhile. If they still get a voltage drop after it’s fully charged, then the battery is probably bad. This type of meter has a built in load, sort of like a heating element, and it checks the battery first with no load, and then applies the load for a specified period of time. If the voltage drops too far during this test, then the battery is bad. If it doesn’t drop, and you are still having problems, then it’s time to look elsewhere, like for a bad starter or voltage regulator.

120-volt Non-Contact Tester

Although not a normal piece of automotive equipment, it can tell you whether you’re about to get a shock or not! A non-contact voltage tester is simply a pencil-like tester with a button on it. You hold the button down as you bring the tip close to a suspected “hot zone” like a wire or even the chassis of a piece of equipment. How does this help you when camping?

Let’s say that you accidentally close the car door on your extension cord and it pinches the wire… not enough to cause a short… but just enough to cut into the hot wire. Since the car isn’t grounded, it’s not going to short out. The body of the car will simply become “hot” and if you happen to be standing on the ground and touch the car body, you could get electrocuted!

Another example… let’s say you set up your barbeque grill and attach the electric rotator for the spit… only you don’t realize that it has a problem and has energized the whole frame of the barbeque grill. You could touch the grill and get electrocuted!

There are a thousand reasons why electrical problems occur, and many times we don’t realize there is a problem until we get a shock. Sometimes the shock isn’t too bad, and just lets us know that something is wrong. But other times, it can be quite extreme. If you have grabbed something tight, it can paralyze your fingers and lock them to it so that you can’t let go. Believe me, I know… I’ve had it happen to me already!  It’s not fun!

You can buy these little testers at almost any hardware or home improvement store for under $10, and they literally can be a life saver! I own several of them, and use them for everything from troubleshooting to just “being safe”. Any appliance can have a problem that you have never noticed…until you use it outside!  Any time you have extension cords being used outside, especially in the rain, you have the potential for problems!  That’s why you should ALWAYS use a GFCI device at the park power post to protect everything “downstream” from it, and even then use the little non-contact tester to make sure there isn’t another problem. Don’t take chances with electricity!