Wholesale Voltage Tester Pen - Auto 12 Volt Battery Voltage Tester Charging System Analyzer Monitor – Tonny

Battery test 

A. With engine off, touch the positive battery post with the red probe and the negative battery post with the black probe.

B. The glowing light will show battery condition.

TECH TIP: Some heavy duty high output batteries may show a  reading above the number 3 light,

causing the number 4 light in the alternator section to glow. This does not indicate a problem.

Alternator Test

A. With engine running, touch positive battery post with the red probe and the negative battery post with the black probe.

B. The glowing light will show alternator output.

C. Light numbers show the following:

1. Bad alternator diode.

2. Normal condition.

3. Loose or slipping belt.

4. Normal condition.

5. Loose alternator bolt, corroded battery terminals.

6. Battery needs charge or cell is shorted.

TECH TIP: Always be sure belts are tight.