To diagnose a battery failure is one of the simplest things to do for the do-it-your-self-er. No special knowledge or skill is necessary. The most common causes are few. 

First, how the battery and alternator work:
The battery provides the initial energy used to start the car, turning the starter motor, and providing spark to ignite the gasoline. Once the motor is running, it's turning causes the alternator to turn. While today's cars run on a 12 volt battery, most alternators provide 14.4 volts of power. This is to keep a charge on the battery, as well as provide power for the rest of the vehicles demands.

The most obvious battery killer is something using power with the engine off. Make sure all lights are going out when door, hood, and trunk are closed. Any special accessories, like aftermarket stereo, amplifier, winch, tracking device, etc should be off when car is not running. If this is not the problem, follow the steps listed below.

1. Poor battery connectivity is common
Corrosion builds up on the posts and the connectors, which inhibits power from the alternator reaching the battery. Removing the terminal(connector) from the battery post needs only a wrench, or a pair of pliers in a pinch. Important! Disconnect the negative terminal first. This is the one marked with a minus (-) sign. Then remove the positive side, which is marked with a plus (+) sign. Getting this backwards can cause big sparks, and much damage to electronic equipment, as well as an outside chance of battery explosion, and/or personal damage! Get it right! Baking soda and water mixed as a paste will clean most of the corrosion off. Sodas like Coke or Pepsi will work in a pinch. For best results, follow up with sandpaper on the post, and on the inside of the terminal where it touches the post.

2. Determine if the battery is getting a charge from the alternator
A battery should read around 12 volts with the engine off. It should read approximately 14.4 volts with the engine running. As low as 13.5 volts is acceptable, especially in smaller vehicles with few accessories. If you do not have a voltmeter, there is a simple test you can run. With the engine running, remove the battery terminal on the negative side, as described above. If the engine continues to run, charge from the alternator is fine. If the engine cuts off, not enough charge from the alternator is the problem. Geosergio Auto Electrical. will repair your alternator or supply you a recondition unit. If you have cleaned the terminals, and the engine continues to run, then the most likely culprit is a defective battery. Geosergio Auto Electrical can supply you with a battery.

3. Making it to this step means the alternator is not charging
Before rushing right out and getting a new alternator, the tension on the belt driving the alternator should be checked. . If the belt is tight, the most likely culprit is the alternator. If you are capable, it can be removed and tested at Geosergio Auto Electrical, once again, for free. It can even be tested it in the car. If the test confirms this, we will repair the alternator. If all still tests OK, move to step 4.

4. Less likely problems can cause battery failure
This is usually faulty wiring. The wiring to the battery, and to the alternator, as well as all connections, should be checked. Signs to look for are corrosion, cracks in wires, and loose connections, especially at the positive terminal on the battery. If th.e problem still cannot be identified, however, a professional will probably be needed.

Contact Geosergio Auto Electrical for your new automotive battery.