Back in the day, maintaining a car battery was part of regular upkeep: you had to pop off the vent caps and top up the fluid with distilled water whenever it ran low. Thanks to modern automotive engineering, most passenger vehicles now run on fully sealed, maintenance-free batteries.

While you will not need to fiddle with modern batteries nearly as much, battery care remains essential for heavy equipment, commercial trucks, and older cars that still rely on vented systems. Even sealed batteries require basic inspections to prevent unexpected breakdowns.

Here is a straightforward guide to keeping your battery running strong.

Battery Maintenance Checklist

1. Inspect and clean the terminals regularly

Whether your battery is sealed or open, certain components need a routine checkup. Aim to look under the hood at least once every six months for personal cars, or every three months for commercial vehicles.

Start by inspecting the terminal posts. If you spot white or bluish crusty oxidation (corrosion), put on protective gloves and clean it off using hot water and a dedicated battery brush. Never touch corroded terminals with bare hands. Left unchecked, buildup disrupts electrical contact, drains your battery, and can cause electrical issues throughout your vehicle.

2. Check the mounting hardware

Vibration is one of a battery’s biggest enemies. Inspect the hold-down brackets, clamps, and tie-down hardware securing the battery to its tray.

Ensure everything is tight and securely fastened. Snug up any loose bolts, and replace broken clips or cracked retainers immediately. A loose battery can bounce around, cracking the plastic casing or damaging internal plates.

3. Monitor electrolyte levels on unsealed batteries

If your vehicle uses an open or serviceable battery, you must regularly monitor the electrolyte fluid levels inside each cell.

The fluid should sit roughly a finger’s width above the internal plates, or right at the designated fill line. If it drops below the marker, carefully top it off with distilled water until it reaches the correct level. Never use tap water, and avoid overfilling. Excess fluid can boil over or splash out on rough roads, spilling corrosive acid directly onto your engine components.

4. Test the electrolyte density and resting voltage

Checking fluid density with a hydrometer reveals how much capacity the battery has left. If the density drops below the manufacturer reference level, the battery is losing its charge-holding ability and needs a full recharge with a bench charger.

You can also gauge your battery’s health by checking its resting voltage with a multimeter. For example, a target specific gravity of 1.25 g/cm3 generally corresponds to a resting voltage of around 12.5 volts. Readings consistently below 12.5 volts indicate that the battery is undercharged or aging out.

After running a bench charge, wait at least 10 to 15 minutes before testing the voltage. Checking right away shows a misleading surface charge rather than the battery’s true resting state.