Review on 🔧 AstroAI 2000 Count Digital Multimeter with DC AC Voltmeter, Ohm Volt Amp Tester - Voltage, Current, Resistance Measurement; Live Wire Testing, Continuity Detection by Terence Dardant

I wish I'd realized before I bought it that accurately testing household batteries (AAA, 9V, etc.) isn't enough. So my quick check is to find a multimeter with built in settings to test AAA, AA and 9V. Now the long version: This multimeter shows you the battery voltage, just not under load. My smoke alarm complained about 9v so I replaced it with a new one and it was happy. Out of curiosity, I checked the one I took with this meter, it read 9 volts! Wait. The? How can it be? Well it turns out that a dying battery can still supply its full voltage if there is no resistance. However, if you add resistance to such a battery, it will not be able to supply the full voltage, which means that it will run out and will not be able to power anything that uses more than a trickle of energy. How to howl loud enough to wake you from a dead sleep when it burns. How much resistance is used depends on the battery type, so most multimeters with battery settings have separate settings for 9V and AA/AAA. . As? I do not know. An online source suggested using a 100 ohm resistor in parallel if you want to use a single resistor to test AAA to 9V. Not perfect, but maybe "good enough". Following her suggestion, I'm going to connect a 100 ohm resistor with alligator clips to the leads of this multimeter and use it to test batteries. Alligator clips are another that's good enough. Many sites recommend soldering the wires from the resistor to the pins. I'm sure it's definitely better, especially if I'm just going to test batteries with it, but I haven't soldered since elementary school so I'll be using alligator clips. :)