Although it's true that today's batteries require less maintenance than they once did, most are not truly maintenance-free. Perhaps it would be more accurate to call them low-maintenance batteries.
If the battery has removable caps, check the water level every three to six months. In hot climates, or if the charging system is malfunctioning, the battery may lose an appreciable amount of water in a relatively short time. Also, "gassing" may increase as a battery ages, reducing the water level. So if the water level is low, find the cause. Simply refilling it to the proper level may be all that's required if the loss is due to normal evaporation. But a low water level may also be an indication of a more serious problem.
The water level should be no higher than 1/8 in. below the bottom of the vent well. To avoid battery damage, make sure the electrolyte level never drops below the top of the plates. Also, avoid overfilling, which may result in electrolyte overflow. Always use distilled water to fill the battery. Chemicals found in ordinary tap water may contaminate the battery.
Never add battery acid if the water level is low. When electrolyte is lost, the water evaporates, while the acid remains in the battery. Adding acid alters the chemical composition of the electrolyte and can cause the battery to fail sooner. Electrolyte should be added only after an accidental spill. Battery additives, like aspirin and other over-the-counter remedies, should also be avoided. None have been proven to extend battery life and may actually decrease it.
Inspect the terminals and cables. If they're dirty or corroded, clean the connections with a scraper and wire brush. If corrosion is unusually heavy, look for a cause. Perhaps the battery was overfilled in the past. Batteries contain sulfuric acid, which will quickly corrode anything in the vicinity if it gets out of the battery.
Keep the top of the battery clean. Use a 50/50 solution of baking soda and water to remove heavy concentrations of dirt and corrosion. A wire brush or specialized battery terminal tool may also be required for a thorough cleanup. Finish the job by flushing the area with clear water, then allow it to dry completely.
Check the battery hold-down hardware. The battery must be securely mounted to keep it from moving when the vehicle is in motion. A battery is a heavy object that will move around if it's not properly restrained. If the battery mounting is slightly loose, the battery may bounce around under the hood as the vehicle negotiates bumps and chuckholes. There are very good reasons why you should not allow this to happen. For one, the battery positive terminal might touch a grounded area of the vehicle body, causing an electrical short. Secondly, constant jarring and vibration is harmful to a battery, and will shorten its service life. Finally, a loose battery puts additional strain on the terminals and clamps. A failed battery clamp could cause the engine to stall unexpectedly.
A fully charged battery is a happy battery. Lack of use is hard on automotive batteries because they're designed to receive a regular charge from the alternator. Any unused automotive battery will self-discharge over time, and the normal parasitic draw caused by on-board computers accelerates the process. The rate of discharge depends on the vehicle, the type of battery and the storage temperature. If a battery is allowed to remain in a discharged state, it will undergo severe positive grid corrosion and eventual failure. In cold weather, a discharged battery will FREEZE and irreversible damage will likely occur.
To safely charge a battery, use protective eyewear, rubber gloves and work clothes, and remove all jewelry. Place the battery in a well-ventilated area, then check the specific gravity of each cell using a hydrometer. Also check the water level. Never charge a frozen battery; allow it to warm to about 60/F before charging. Reinstall the vent caps before charging. While the charger is unplugged, connect the leads to the proper battery terminals. For side-post and studded batteries, use adapters to ensure adequate contact.
If the charger requires manual adjustment for current or shut-off, determine the proper current and length of charge based on the battery's rating. Some chargers automatically adjust the current and length of charge according to the battery's state of charge, then shut off when the battery is fully charged.
Plug in the charger and turn it on. Don't wiggle the connections at the battery to check contact while the charger is in operation. Sparks may cause the battery to explode. Don't allow smoking, open flames or sparks near the battery. Reduce the charging rate if the battery becomes hot to the touch.
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