Battery Testing

Battery testing should form part of a regular maintenance routine as pre-emptive battery replacement can help eliminate many of the costs and problems associated with a flat battery.

Voltage and Specific Gravity

Voltage (V) and Specific Gravity are measurements used to determine a battery’s state of charge. Voltage is a quick and easy way of measuring charge levels and is measured by connecting either a multi-meter or voltmeter and obtaining a DC reading. Always connect the multi-meter parallel to the circuit being tested, observing polarity; otherwise the result will be negative.

Hydrometers measure the specific gravity of the electrolyte and indicate the density of electrolyte compared to water. As this requires access to acid reservoirs it is only suitable for use with maintainable batteries.

Century also offers a range of battery testing equipment designed to take the guess work our of battery testing.

View the range of testers available.

Testing Methods

Unloaded TestingThis is performed using either device when there is no current draw on the battery. A specific gravity reading of 1.275 to 1.290 shows a full charge whereas a reading of < 1.250 indicates that the battery should be recharged. If the stabilised open circuit voltage is below 12.55V this also indicates recharging is required.

Low Load Testing This is conducted using a multi-meter or volt meter whilst running an accessory, such as the headlights, and taking a voltage reading. The battery in a 12V system should have at least 11.5V DC with the lights on and if the voltage drops below this level the battery needs charging.