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Test Tool Sorts Out Battery Capacity

The phrase keep it simple applies to a nifty electrical test instrument called a load tester. It is a voltmeter combined with an internal switched resistance load, which simulates the approximate load put upon the battery by a starter, for example.

A battery load tester can give you an evaluation of the battery’s condition by applying a load resistance during a voltage test to measure the true load voltage. A voltage test across the terminals tells very little besides the fact that the battery is giving you some electrons without the benefit of doing actual work.

Begin the test with a fully charged battery.

Connect the load test meter across the battery terminals as you would when jumping the battery with positive to positive and negative to negative. The unloaded voltage should read 11 to 12½ volts for a 12-volt battery.

A switch on the tester puts a resistance on the battery while the voltage is being tested. Switch on the load for 10 seconds. The meter will indicate if the battery is good, weak, or bad, and it will indicate the battery output voltage.

During the 10-second test, a 12-volt battery may drop below 11 volts or lower depending on its condition. You can decide the condition based on the voltage and amp-hour rating of the battery test. A battery can be discharged, recharged, and measure 12 volts unloaded. That charge level may be able to start the engine. If it has one or more weak cells and, thus, is unable to absorb a full charge, the tester will show a low-voltage reading and a weak or bad condition. If you depend on this battery to muster another start without a charge boost from the electrical system generator, a replacement may be in order. A nice bonus to owning a load tester is that it gives you an indication of the output voltage of the charging system.

A load tester is not a definitive tool to indicate that the battery is either good or bad. It will alert you to the possibility that the battery may have one or more weak cells that, in time, will fail.

Tackling a twisted-off spark plug

Ageless Iron Almanac reader Maurice Pederson was challenged by a twisted-off spark plug in his John Deere model A. “This is not a case of restoration since it was already running good,” the Valley City, North Dakotan relates. “When I put the wrench on one of the plugs, I was really surprised to find out I could not move it.”

Pederson continued to work on loosening up the plug until – you guessed it – “it twisted off just below the next part of the plug body,” he recalls.

Not wanting to have to remove the cylinder head, Pederson improvised a solution. First, he ground a hacksaw blade down so it would fit through the plug’s body. Then, he positioned the blade in a bayonet-type handle, using it to cut a slot through the spark plug body so it would collapse. Prior to cutting, he positioned the handle so it would cut on the pull stroke. “I cut the slot deep on the innermost threads because I didn’t want to damage the outer threads,” he says. “I ran the thread chaser in to clean up the threads” after collapsing and removing the plug.

Before installing a new plug, Pederson started the engine to eject any foreign matter so it wouldn’t get caught in the exhaust valve.

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