Electronic battery tester with normal/cold test modes and terminal connection detection

Abstract

An electronic battery tester is disclosed with normal test and cold test modes comprising: a first circuit for applying an AC current load to a battery under test to induce an AC signal across the terminals of the battery; a second circuit for measuring the induced AC signal and converting it to a first voltage potential signal which is a measure of the battery's internal resistance; a circuit for adjusting the first voltage potential signal to a second voltage potential signal; third circuit for generating a threshold voltage potential signal at a first value when the battery tester is in a normal test mode and at a second value when the battery tester is in a cold test mode; and a comparison circuit for comparing said second voltage potential signal to said threshold voltage potential signal to determine a condition of the battery. The battery tester also includes terminal connection detection capability comprising: an indicator driven by an electronic tester unit for indicating a connection when first and second supply leads and first and second return leads are properly connected to the battery under test through corresponding first and second connectors; the electronic tester unit including a circuit governed by the first and second return leads for inhibiting the indicator from indicating a connection when one of the first and second return leads are not properly connected to the negative terminal of the battery under test through the second connector.