Review on Dlyfull Universal Battery Tester: LCD Display & Digital Voltage Resistance Checker For AA AAA C D 9V 12V 18650 CR123A 2CR5 CR2032 Cells by Phillip Samuel

There are battery testers on the market, but not all are accurate, easy to use or even do a good job. As a result, up to now I’ve been using a standard Digital Multimeter (DMM) to test my batteries. This works, but it only tests the battery’s voltage at no load. Marginal batteries may show full or nearly full voltage at no load but fail when placed in a real device.So all this time I’ve wondered when someone would come out with a battery tester in multimeter form. Finally, Dlyfull has offered their Universal Battery Tester with LCD Display. This looks like a small multimeter but it is dedicated to testing batteries. And it tests quite a few different battery types including Ni-MH, Ni-CD, Li-ion, AA, AAA, C, D, 9V, 12V, 18650, CR123A, 2CR5 and CR2032. It also tests many more types as well both rechargeable and non-rechargeable. In addition to measuring the battery’s voltage, it measures the percentage of life left in the battery (an estimate, of course) and the internal resistance of the battery.The internal resistance is important. In theory, a "good” battery should have 0Ω internal resistance. As a battery deteriorates, the internal resistance increases and reduces the batteries voltage output value. The Dlyfull Universal Battery Tester can measure and report the resistance at the same time that it reports the voltage. This is something that a DMM and the majority of inexpensive battery testers can not do.The Dlyfull Universal Battery Tester goes to sleep automatically to save its own internal batteries and wakes as soon as it sees a battery under test. However, it should be turned off when not in use. If the test leads are reversed the tester reports this as an error. These are all good things. Less good is that Dlyfull does not include a case with the Universal Battery Tester (even a cheap one would have been appreciated.) They do, however, provide the batteries that run the tester. The instructions are poorly written and should have explained the value of the internal resistance and why it is important to battery testing. Finally, I wish that the LCD screen was backlight. It can be hard to read under certain circumstances.But these are nits. In my case, I used an old, small case to protect the unit so I am good here. And I now have what I always wished for—a capable informative battery tester.