If the battery is not the original equipment battery, check the label. Usually mounted on top, the label has information on the date the battery was first sold, in the form of numbered dots that are punched out. One is punched out to indicate the year, and others indicate the month sold. By comparing the date it was sold to the number of months of its advertised life will give you an exact idea of how much useful life the battery has left. A battery due to be replaced is another bargaining chip for you.
Look over the battery hold-downs and the battery box itself. Is there a battery hold-down at all and is it the original part? Batteries need to be securely mounted in the vehicle to prevent damage to the battery itself and to the engine compartment and nearby wiring, hoses, etc. If the original hold-down needs to be installed. Rope or bungee cords aren’t enough to prevent vibration damage to the battery and potential acid spills.
The battery tray or box should be examined for signs of serious corrosion. Batteries that aren’t maintained, where corrosion has been allowed to grow on the terminals and migrate down the hold-downs onto the vehicle’s battery tray, can eventually become serious enough to cause the battery tray to disintegrate. The corrosion then attacks the unibody itself. If the battery is a type with removable cell covers (not a “maintenance-free” type), pull them out to see if the electrolyte level is up to the mark (usually a split ring inside). A battery with a low level could indicate either that it hasn’t been maintained, or that the vehicle charging system is overcharging, something to note for your mechanic to test.
Many cars have electrical components in the engine compartment that you can visually examine. On the engine, look at the distributor cap for cracks or signs or carbon tracking. Look at the spark plug wires – they should be clean, neatly-routed and free of cuts, abrasion spots or exhaust burns, and the same for secondary wire from the distributor cap to the coil. Many cars have their main electrical-system relay boxes in the engine compartment, either near the battery or along the cowl/firewall area. Pop the plastic cover off the relay box and look inside. Usually the inside of the plastic cover has a diagram to indicate which relay is for which system. Don’t be alarmed if there is a relay or two missing.
On conventional batteries, pry the cell covers off and check the electrolyte level – a really low level is another indication the vehicle’s owner wasn’t performing routine maintenance.
Excessive battery acid and corrosion near the battery often indicate an overcharging condition. Have a mechanic check this out.
Eagle Ridge GM Mobi