How to Keep Your Battery Alive

A little maintenance will keep your battery charged through the cold months as well as the warmer ones.
Instructions
STEP 1: Estimate the age of your battery. If it's more than four years old, replace it.

STEP 2: Ask your mechanic to perform a 'load test' on your battery. This tests whether the battery is capable of generating sufficient charge on below-freezing days. If it fails the test, replace the battery.

STEP 3: Clean the battery terminals if they are encrusted with deposits. Use a wire brush dipped in baking soda and water to clean them of corrosion and ensure that the deposits do not block the flow of electrical current.

STEP 4: Check to make sure the water level in the battery hasn't dropped. You can do this on conventional batteries by popping off the plastic cover and checking to see that the water inside reaches the plastic filler necks. Add distilled water if necessary. Maintenance-free batteries, however, generally have an indicator light that goes black when the battery needs service; take these types to a mechanic for service.

STEP 5: Check the tightness of the battery cable ends. A loose battery connection can prevent your car from starting and acts just like a dead battery. If you can move the battery cable ends that are attached to the battery terminals at all, they are too loose.

STEP 6: Check that the battery is securely fastened in the battery tray. A loose battery that is allowed to shift around can cause damage if it is able to tip over under the hood. Excessive vibration will also shorten the life of your battery.

STEP 7: Consider investing in an engine or battery heater if you live in an especially cold climate; the heater can reduce the power that's needed to start your car.

Tips & Warnings
In severe cases, the battery may need to be recharged with a battery charger to bring it back to life.
Your car may not be starting because other components in the charging system are failing, or because of a bad starter motor.
Recharging your battery improperly may fry it and other electrical accessories in your car, so it needs to be done slowly.
Keep open flames away from your battery - the chemicals inside it are combustible.
Battery acid is highly corrosive. When adding distilled water to the battery, take care that acid doesn't splatter on your skin or clothes.