Review on Dlyfull LCD Battery Tester - Universal Checker For AA AAA C D 9V CR2032 CR123A & More, 2X AAA Batteries Included by Brandon Grzankowski

After reading the various reviews I decided to purchase this tester. As soon as I received it I 'tested the tester', as some reviewers didn't rate it well. I knew I had a batteries that were weak (based on the device), worked but were used, and new batteries.The tester shows a variable range of power (with good, weak, & poor ranges) and accurately reflected the weak battery (based on my device use) as weak, the less used battery in low end of the good, and new battery as a top good readings. When I tested the batteries on my wireless keyboard (which my Mac showed as 10% and needing replacement) it reflected the battery in the low end of good.I then tested the batteries that were laying in a drawer so I know which were new and which to toss. The unit works.Update: One thing to note, if a battery tests mid way in the good zone it is actually weak! I have batteries that are at not working in a device and the tester will show into the good zone. I now look to see if a battery shows all the way good to verify it is good.