Maintenance-Free Batteries Still Need Some Upkeep

Most modern cars have switched to sealed maintenance-free batteries, so topping off electrolyte levels with distilled water is no longer a routine chore. Unlike conventional flooded lead-acid batteries, sealed designs use lead-calcium-alloy grids and pressure-relief valves to reduce water loss.

Valve-regulated lead-acid, absorbed glass mat, and gel batteries combine oxygen with hydrogen ions at the negative plate, eliminating the need to check electrolyte levels.

That doesn't mean a maintenance-free battery can be forgotten. Terminals can still corrode, so cleaning them is one part of upkeep. Visual checks for cracks, leaks, or bulges also matter. Sealed batteries typically last longer than serviceable ones, but they are not immune to sulfation, where lead sulfate crystals build up on the plates and slowly reduce the battery's ability to hold a charge.

Keeping the battery fully charged is important, especially if the car sits unattended. A trickle charger may help extend its lifespan, and for a long trip away, disconnecting and storing the battery are worth considering.

For DIY owners, AAA advises inspecting for leaks and corrosion and checking voltage with a digital voltmeter. Unhook the negative terminal first, then the positive cable. If the battery is leaking, bulging, or damaged, replace it. Otherwise, clean the terminals with baking soda and water or battery cleaner and a wire brush.

Once everything is dry, reconnect positive first, then negative. Battery acid can eat through concrete, and improper handling can cause serious injuries, so wear the right protective gear.

Servicing a sealed battery is not a simple DIY project. iFixit has a guide for checking and refilling electrolyte levels, but it involves drilling holes into the case and is generally not advised. For anyone unsure about battery work, the safest move is to have a trained technician handle it.