There is an assortment of reasons as to why a battery might go bad. Of course, the most common cause is the battery's age. If your Chevy Astro's battery has been in use for four to five years, then it is most likely reaching the end of its life and needs to be replaced. Other causes of low battery voltage include: leaving your vehicle's lights or ignition switch on, corroded terminals, a damaged battery or malfunctioning alternator. To check to see whether your Chevy Astro's battery needs to be replaced or whether the problem lies elsewhere, you need only one or two simple tools and a bit of time.
Turn off all switches and accessories, open the hood on your van and locate the battery. You'll need to remove any plastic guards or shields that are on the battery. You must have free access to the terminals.
Check your Astro's battery for any signs of corrosion. If you see any dirt or corrosion on the terminals, clean it off, using a post and terminal cleaning tool. These tools are inexpensive and can be purchased at most auto supply stores.
Ensure that your voltmeter is set to 12 volts (some meters can be set to test batteries of different voltages). You must then connect the positive lead or clamp of your voltmeter to the positive terminal on your Chevy Astro's battery. Your positive lead/clamp should be red or yellow, while the positive terminal on the battery is usually marked with a plus (+) symbol.
Attach the negative lead or clamp of your voltmeter to the battery's negative terminal. The negative clamp of your voltmeter will, in most cases, be black. Your battery's negative terminal is identified with a minus (-) symbol.
Read the display on your voltmeter. For a battery that is fully charged, you should see a reading of at least 12.6 volts. If your Chevy Astro's battery isn't holding a full charge, you'll see a reading of approximately 12.4 or less. In this case, it may need replacing.
