Tuesday, January 11, 2011

Jumper Cables

A good sturdy set of jumper cables can be invaluable when you find yourself with a dead or low chassis battery that won't start your rig. It's usually not hard to find someone who is willing to "lend" his vehicle so you can get going. But if neither he nor you have jumper cables, then you're stuck. In a motorhome, however, you have the means of being independent and having the ability to jump-start the engine using the house batteries.

What you need is a set of cables long enough to reach from the chassis battery under the hood to the house batteries. Don't waste your money on cheap cables with .lighter wires and chintzy clamps.

High levels of electrical current running through a small amount of conducting material may cause the material to heat up, and if the circuit is left running for too long, the conducting material may be destroyed as a result of this heat. The more conducting material is present, the more current can safely run through the cable. Jumper cables have to transmit enough energy to jump start a car, and if they aren't thick enough, they won't be able to get enough current across from battery to battery. Heavy duty jumper cables are more likely to be able to transmit the required amount of electrical current. Heavy duty jumper cables come with bigger, stronger alligator clips. This makes for better connections between the two batteries, which reduces the chance that you will have to jiggle the clips around to find a good connection. Because heavy duty jumper cables are bigger with bigger alligator clips, you can hold the clips further back when you attach them to the battery terminals. This means that you don't have hold your hands as close to the place where the cable makes a connection, where large sparks may occur.

Based on the above, number 2 gauge cables, rated for 600 amps, would be recommended. And be sure to get them long enough to reach from under the hood to the battery compartment.

Sparking can be reduced by connecting the cables in the proper order:

Connect the 'hot' (+) connector first, and the ground (-) connector second. If the battery or the cables are live, this will avoid accidentally shorting a cable connector to a nearby ground such as the battery holder or the hood. When disconnecting, reverse the procedure, and disconnect the ground (-) first and the hot connection (+) second.

Also when working with jumper cables, connect/disconnect both ends of one cable first before working with the second cable.

Contributors: Barry Barnes, WxToad

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