Power to Spare

In the January issue of BWS, Harry Hungate writes about how he overhauled his electrical system starting with the batteries in order to avoid a fire. Here are just a few of the tips he included in the article on soldering battery cable terminals and updating circuit breakers. Be sure to pick up the January issue for his full article.

Some useful tips when soldering battery cable terminals:

1.      Wrap a wet paper towel around the cable about one inch (25mm) from the end of the insulation to limit the molten solder from wicking up into the cable. This will also help prevent heat damage to the insulation.

2.      Using vise grip pliers, hold the battery terminal over your heat source (stove or propane torch) and fill the cable cavity with solder. When full, insert the cable and add solder until it overflows. Cool quickly with a wet paper towel.

3.      Coat the soldered terminals with silicone grease and cover them with heat shrink insulation for maximum corrosion protection.

Time spent pre-planning this project will pay handsome dividends:

1.      Select a protected place with adequate access to mount the circuit breakers and bus bars that requires no more than one meter (39 inches) of cable between the farthest positive battery terminal and its circuit breaker.

2.      Make a sketch of all of the 12-volt consumers and sources that will be connected to the positive and negative bus bars. Add at least 10 percent more for future growth. Also plan for the addition of one or two more circuit breakers. (You will thank yourself for this sooner than you might think! I added one circuit breaker and battery before the project was completed, and have since added one more circuit breaker for a dump load controller for our wind generator.) If you must “double up” on some of the connections, place no more than three ring terminals on one bolt or screw, and stack the terminals carrying the heaviest current next to the bus bar.

3.      Remember that you are going to have to be able to add and remove wires from this system, so allow adequate access space.

4.      When constructing the bus bars, drill and tap all of the holes for the cable terminal screws, including the 10 percent spares. The bus bars must be thick enough to provide three full threads contact with the bolts. Snug the screws for the 10 percent spares in place—otherwise, you are not likely to remember where you stored them a year from now!

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