Simple AAA Battery Tester - 1.5V - Homemade with 1 LED.

Although commercial 1.5 V battery testers exist for AA, AAA, and D battery sizes, making a homemade tester was a challenge; building one for just 1 battery was not possible for me, since a discharged 1.5 V battery (less than 1.15 V) cannot light up an LED of any of the colors I have tested.

So I had no choice but to use 2 batteries in a radio battery holder; by soldering 2 alligator clips to this same holder, we also have a homemade repair tool for disassembling and repairing remote controls.

Component soldering phase; this is a very simple assembly consisting of only 2 solder joints.

Solder joints and view of the 3 components already soldered.

Example of connecting the battery holder to the tester circuit.

2 batteries in good condition measure between 2.85 and 3 V and light the LED at almost 100%; the idea of this circuit is to push the LED's lighting to the limit, so that in the event of a voltage drop, the LED tends to dim or turn off.

In the event of a dim or off LED, we could perform a second check: by removing the diode on the right side, we can connect between the 2 diodes, so the circuit will light up with less voltage. This would be an auxiliary check.

I must say that this is not one of the designs I liked the most, nor one of the most complete, but building a tester for 1.5 V batteries was a challenge after seeing the problems there were with lighting up LEDs of different colors; in the end, I made it with a Blue LED.

Other Guides dedicated to battery testers: Electronics Skills

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