It takes three basic steps to measure the specific gravity of the battery with a battery hydrometer. First, you draw a sample of battery acid from the battery using the hydrometer. Secondly, you read and record the specific gravity readings from the hydrometer scale.
For non-sealed batteries, test the specific gravity in each cell using a hydrometer. For sealed batteries, use a digital voltmeter to measure the open circuit voltage between the terminals. Some batteries have a built-in “Magic Eye” hydrometer that tests the state-of-charge in one of the six cells.
If the temperature isn’t 80°F, use the Temperature Compensation table to adjust specific gravity readings or open circuit voltage. Confirm the manufacturer’s specifications for a fully charged battery. For non-sealed batteries, test the specific gravity in each cell using a hydrometer.
Voltmeter - to measure the voltage of the battery before and after the gravity test, to confirm the battery is holding a charge. It is important to note that when working with lead-acid batteries, it is crucial to take safety precautions and handle the battery with care to avoid injury or damage.
The density of the bulb of the hydrometer allows its floatation level to measure the specific gravity of the battery acid and hence the level of charge. This reading shows how much the battery is charged or discharged. If the specific gravity is higher, the battery is fully charged.
The most accurate test involves checking the battery voltage and fluid condition using a DC voltage meter and hydrometer, both of which are available at local stores. If problems persist, there are additional troubleshooting steps you can take. Wondering if your marine battery is on its last legs?