Battery voltage is temperature-sensitive, and you’ll need to ensure that batteries are not overcharged when they are hot and not undercharged when they are cold. Most chargers have an optional remote temperature sensor that’s placed in the middle of the battery bank (adhered to the side of a battery). Since a battery’s temperature compensation requirement varies, always check manufacturer’s specs and program your charger accordingly.
Even if a battery bank is working well, performing routine maintenance can prevent future problems. All batteries should be thoroughly inspected at least once or twice annually. The cases and terminals should be kept clean and corrosion-free. While flooded batteries typically show corrosion buildup around the terminals from gassing, it should be minimal. Sealed batteries should not have any buildup.
To neutralize any escaped acid, wipe battery cases and terminals with a clean cloth or soft brush dipped in a baking soda and water solution (1 pound of soda to 1 gallon of water), make sure vent caps are on and securely tightened. A bubbling solution is a sign that some acid is present; wait until bubbling stops and then wipe with clean water and dry. Be careful not to let anything into the battery through the vent caps.
Once the cases and terminals are clean, check the terminal connections and inspect the battery cables for any wear or loose crimps, and replace if necessary. Clean and recoat terminals and lugs with a thin layer of anticorrosion treatment (petroleum jelly works). Always leave your batteries clean so you can easily see any future corrosion or acid leakage.
Flooded batteries need to have their electrolyte levels checked every one to two months. Even if batteries only need to be filled every six months or so, checking water levels more often is recommended to ensure the plates are never exposed. If this happens, that part of the plate will quickly oxidize and block the chemical process there. Even if this only happens to one cell, it creates resistance and unequal charging throughout the battery bank and can reduce the whole system’s efficiency and battery bank life.
Electrolyte should completely cover the plates, but be about 1/4 inch below the cell fill tube. Overfilling is a common mistake. If you often find acid on your batteries, check that you aren’t overfilling the cell. Shining a small flashlight into the cell can help you see the electrolyte level.
Only use distilled water for filling. Tap water, even filtered, can contain impurities that will harm your batteries. Use a funnel to help avoid spills. Hydrocaps and watering systems can help you keep batteries filled, but they are not a substitute for regular inspection. Also note that some of these devices need to be removed during equalization.