Car Care Tips: Battery Care
If you want your car to keep on starting, take care of your battery.
Basic Battery Car from Popular Mechanics
There's nothing but a loud buzzing noise coming from under the hood when you try to start your car. Jumper cables get you up and scurrying to work--but you need another jump to get home. Time to pull some maintenance on the battery.
Automotive batteries have a finite life span. Undercharging, overcharging and heat all team up to degrade your battery. Poor electrical connections make it more difficult for even a good battery to do its job.
ALL CHARGED UP
Start any battery maintenance program by checking open-cell voltage, either with a dedicated battery tester or a voltmeter. With the battery fully charged and all electrical drains-dome light, warning buzzer, etc.-shut down, the voltage across the terminals should be 12.5 to 12.6 volts. If the battery is not completely charged, but still adequate to turn over the motor, you may see a voltage closer to 12.0 volts.
If the battery shows less voltage or won't take a charge, it's time to get out the hydrometer. This device checks the proportions of sulfuric acid and water in the electrolyte, which is a precise indication of the level of charge. Pull up the battery fill caps--if you can. Add distilled water to any cells in which the level of electrolyte isn't touching the bottom of the fill port. Use only distilled water. The minerals in tap water will eventually reduce a battery's capacity.
If your battery is one of the so-called low-maintenance varieties, you may not see any filler caps. These batteries claim to never need water added. While it's true that they have a slightly different chemistry that consumes less water, and the level of electrolyte in the cells is deeper over the top of the plates, eventually these batteries run out of water and die. Look carefully and see if there is a way to pull up a set of filler caps. They may be hidden under a sticker that can be slit open. Others are permanently sealed shut.
If the level of electrolyte is very low, suspect a charging system that's generating too high a voltage. The maximum voltage you should see across the battery terminals with a fully charged battery and an engine running well above idle is about 14.6 volts. Another cause of low electrolyte is excessive heat. Sun Belt drivers should top up battery levels regularly because underhood temps will climb high enough to drive water out of the battery very rapidly, even if the charging system is doing its job correctly. If your vehicle came with an insulator around the battery, be sure it's in place and in good shape.
Car Battery Care - Family handyman
How to take care of Automotive Batteries - WikiHow