A DIY LED Battery Voltage Meter
A voltage meter is a device for checking the charge in your batteries. It tells you the output voltage from the battery, which you then compare to the voltage output labeled on the side of the battery. This enables you to know when to replace the battery before it stops powering your device. The only problem is that a voltage meter can be expensive. However, if you want to check the voltage in your battery, there's an inexpensive method -- make your own DIY battery voltage meter using light emitting diodes (LEDs).
Things You'll Need
- 4 different voltage LED lights
- Small cardboard or plastic container
- Pen
- Small Phillips screwdriver
- AWG 18 gauge wire
- Knife
- Wire strippers
- Insulating tape
- Battery
Instructions
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1
Make four small equidistant holes in the lid of the container, slightly smaller than the metal base of your LED lights. This will be used as your DIY meter box. A small Philips screwdriver pushed through the lid does the job. Loosen the lid, but leave it in place.
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2
Insert the four LED lights into the holes, so that the base protrudes below the lid, but the light is visible on top of the lid. Make sure that you position the LEDs so the voltage is sequential. This means you have four LEDs in line. For example, you have a 1 volt LED at one end and a 6 volt LED at the other. The voltage is labeled on the base of each LED. Write the voltage of each LED next to where it's placed using a pen.
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3
Cut eight strips of thin single core wire using a knife. AWG 18 gauge wire or similar is fine. Cut six strips at the distance between the LEDs in the lid of your container, then cut the other two strips 18 inches long. Use wire strippers and remove just under ¼ inch of plastic off the ends of the eight strips of wire.
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4
Lift off the container's lid and turn it over so you are looking at the base of the LED lights. Connect two short strips of wire to the two terminals on the highest voltage LED in your line. So if the highest voltage LED is 6 volts, attach two wires to the terminals. Use small strips of insulating tape to attach the wires.
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5
Attach the opposite end of the two wires attached to the LED to the terminals on the next highest LED in line. But also attach another two short wires to the same terminals. Use tape to hold the wires in place. This means you have two wires attached to each terminal; one set connected to the other LED and one set unattached.
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6
Repeat the process by attaching the opposite ends of the wires from the second highest voltage LED to the third LED. Ensure you also attach the last two short wires to the LED as before. Attach the opposite ends of the wires from the third LED to the last LED in line, ensuring you also attach the two long wires to the two terminals.
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7
Make a small hole in the side of the base of the container. Use a small screwdriver to make the hole. Feed the two long wires through the small hole from the inside of the container so they extend on the outside. Replace the lid on the container. Use strips of tape if the lid is loose. Carefully, pull the two wires a little further out of the hole in the container so that about 12 inches is exposed.
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8
Get the battery you want to test nearby. Check the voltage on the battery's label. Attach one wire to one battery terminal and the other to the remaining battery terminal. The LED lights will light up, depending on the voltage from the battery. For example, if the battery output is 2 volts, you find the lowest voltage LED is bright and the second LED, not so bright. You can tell the charge of the battery by comparing the voltage on the battery's label to the corresponding LED. If you're testing a 4 volt battery, but only the 1 volt LED lights up, your battery needs replacing.
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Tips & Warnings
The output from most batteries is between 1.5 volts to 6 volts, so buy a 1 volt, 2 volt, 4 volt and 6 volt LED.
References
- Photo Credit Polka Dot Images/Polka Dot/Getty Images
