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Ruben Fixit

Cell Phone Li-ion battery tester

•1 min
batteriescell-phoneli-iontestingbuilds

A small pale green enclosure with a green LED above a red LED, beside a printed scale marked 100%, 80% and 0%.

While working at Macalegin Electronics I discovered that many times we need to verify the charge on a cell phone battery. We have a multimeter but is a little cumbersome to use especially when testing several batteries at once.

So I had the opportunity of designing and building a Li-Ion Battery tester for quick and easy battery charge indication.

It consists of one green LED, one red LED, and adjustable leads.

When the leads come in contact with the battery the LED’s will light up as follows:

  • Green only - the battery charge is ~80% to 100%
  • Green & Red - the battery charge is between 0% and ~80%. If the green LED is noticeably brighter than the red LED, then the battery charge is between ~65% and ~80%. If the red LED is noticeably brighter than the green LED, then the battery charge is less than ~10%.

The edge of the enclosure with a row of movable header pins protruding, labelled for positive and negative polarity.

The opened Hammond enclosure: one half holds the point-to-point wired circuit with the green and red LEDs, resistors and a transistor; the other half holds the two lead sockets.

https://everycircuit.com/circuit/6522073815973888

To adjust the input voltage: Select the power source in the top right corner, then select the wrench in the bottom bar. then use the wheel in the right corner to change the voltage.