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 Jon Thompson

I dont know how accurate the readings are but they are fairly repeatable. Testing various good and not so good batteries I have showed more or less resistance as expected. One reviewer says it puts no load on the battery because it displays the same voltage as a regular multimeter, this is not true. The displayed voltage is the unloaded voltage but it does put a load on to test the resistance. I put a current meter in series and it uses a few short pulses of load to do its calculations.