* Battery is Weak: The most likely scenario is that the battery is simply too weak to provide enough power to start the car on its own. Jumping the car gives it a temporary boost, allowing the starter motor to crank and ignite the engine. However, once the jump cables are removed, the weak battery can't sustain the power needed to keep the engine running.
* Battery has Internal Damage: The battery could have internal damage, like a short circuit or a broken plate. This can prevent it from holding a charge properly, even if it seems to have some power initially. Jumping the car can mask this damage, but the battery will quickly lose its charge again.
* Other Issues: While less common, there could be other issues contributing to the problem, such as:
* Alternator Problems: If the alternator isn't charging the battery correctly, the battery will gradually lose power even when the engine is running.
* High Electrical Draw: A parasitic drain from a faulty accessory or component could be draining the battery even when the car is off.
What to Do:
1. Check Battery Voltage: Use a voltmeter to test the battery voltage. A fully charged battery should have around 12.6 volts. A voltage below 12.4 volts indicates a weak battery.
2. Check Alternator: If the battery voltage is low, start the engine and check the alternator output. It should be around 13.5-14.5 volts.
3. Inspect Battery Cables and Connections: Make sure the battery cables are securely attached to the battery and the starter motor.
4. Consider a Battery Load Test: A battery load test can determine if the battery is capable of delivering enough power to start the engine.
It's important to note that you should replace a weak or damaged battery as soon as possible. Driving with a weak battery can lead to further damage and potentially strand you with a dead car.
