>>2944315
I have this cheap guy, it’s accurate like 90% of the time, but I have run into a couple batteries that need a real load put across them to tell what’s going on. The HF one (picrel) is ok as long as you’re not testing big batteries, but not worth much when you get like 800CCA+ batteries that are right on the edge.

Recently had a car battery that would test “Good” on the electronic tester, and then with the load tester it would be “Good” for about 3 seconds, then drop off nearly dead. It was like a switch was opened after a bit of a load.

You could also get a damn meter and crank the starter or turn on some accessories and watch the voltage drop.