Hal-Hen 1940s Battery Tester

This dual-scale battery tester carried the Hal-Hen name. It was one type of battery tester used in the 1940s to test both A and B batteries.

This tester had 2 scales—one ranging from 0 to 2 volts for testing "A" batteries, and the other ranging from 0 to 50 volts for testing "B" batteries. Notice that this was a 0-centered meter. Thus it didn't matter whether you put the probe to the positive or negative contact on the battery—the meter just read to the left or to the right depending on the polarity.

To switch scales, all you did was use the "A" end of the probe for the 2-volt range, and the "B" end of the probe for the 50-volt range.

Normally (by convention) you touched the one tip of the probe to the positive terminal of the battery, and touched the "foot" (7-o'clock position) or the "knob" (12 o'clock position) to the negative terminal of the battery.

With this meter there was also a fold-out aluminum disc so that you could simply set the base (negative terminal) of the battery on to make battery testing even easier. This worked for batteries such as AA, C and D cells.