Download Battery Tester from Flashlight Bulb - DIY!

A Free Do-It-Yourself Tip from DisasterGuy.com
Battery Tester from a Flashlight Bulb: DIY!
A piece of wire and a flashlight bulb are all you need to make a battery
tester. The one shown above uses a flashlight bulb from a flashlight with one 1.5volt battery. The piece of tape on the wire says “1.5 volt.”
Take the insulation off one end of a wire, bend it into a loop around a pencil,
and twist it tightly. If your flashlight bulb won’t fit in, untwist the wire until it can,
then re-twist. Take a little insulation off the other end of the wire so you can
complete the circuit and make the bulb light.
You use it by putting the wire on one end of the battery to be tested, and
the bottom of the bulb on the other end of the battery. Look for the brightness
of the light to get an idea of how much juice the battery has in it.
We used a voltmeter to test batteries with mixed results. Yes, it would say
if a battery was producing something like 1.5 volts. But we couldn’t tell if there
were enough milliamps to light a flashlight bulb. This test rig works.
You can also make 3-volt, 4.5-volt, 6-volt, and 12-volt battery testers using
bulbs of the appropriate voltage. We soldered wires to a 12-volt turning signal lamp
from an automobile to test terminals in that vehicle.
One DON’T: Do not use a 1.5-volt lamp to test a 3-volt battery, or use any
lamp to test for more volts than the lamp was rated for. You’ll burn out the bulb.
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