Fortunately, you can easily do a basic health checkup on any type of lead acid battery by hooking it up to a simple-to-use digital voltmeter. If you have an open-cell battery that lets you access the liquid inside, you can do a more rigorous checkup with a battery hydrometer.
Checking an open-cell lead acid battery—that is, a lead acid battery with caps that can be opened to access the liquid inside—with a battery hydrometer is most accurate when the battery is fully charged. Closed-cell lead acid batteries without the access caps cannot be tested this way.
Charge the battery fully at least 8 hours before testing it. Lead acid batteries recharge in various manners based on their function and manner of installation. For a lead acid vehicle battery, drive the vehicle around for at least 20 minutes. For a lead acid battery connected to solar panels, let the battery charge fully on a sunny day.
The liquid-filled lead acid batteries used in automobiles and a range of other products have many great qualities, but are also known to “go bad” with little warning. Fortunately, you can easily do a basic health checkup on any type of lead acid battery by hooking it up to a simple-to-use digital voltmeter.
If the voltage reading is lower than the manufacturer’s specifications, the battery may be weak and need to be replaced. If the voltage reading is within the manufacturer’s specifications, the battery is likely in good condition. To get a more accurate reading of a lead-acid battery’s health, you can use a hydrometer.
Adjust your specific gravity reading based on the liquid’s temperature. The specific gravity chart for lead acid batteries assumes a liquid temperature of 80 °F (27 °C). That said, the liquid in your battery probably isn’t at this ideal temperature.