Review on 🚗 AUTDER 12V Digital Car Battery Tester - Voltmeter & Alternator Charging System Analyzer | Test Battery Condition & Alternator Charging | LCD Display & LED Indication | 13.5" Lead Length by Len Cooper

This is a fairly well designed device. I used it to make sure my wife's car battery was really dead. It reports battery voltage and can indicate if the alternator is working properly. Just don't rely on the instructions, some of the worst I've come across. The little booklet was written by someone who had only a cursory knowledge of English. Once you understand what a tester is supposed to do, just try it and you'll quickly understand how to use the switch settings and what it's telling you. Then read the instructions.