* Battery Age and Sulfation: A 20+ year-old battery is extremely unlikely to hold a charge well. Lead-acid batteries (like those used in the Tempo) naturally degrade over time. Sulfation, a buildup of lead sulfate crystals on the plates, significantly reduces their ability to accept and retain a charge. This is the most likely culprit.
* Internal Short Circuit: A short circuit within the battery itself can drain it rapidly. This could be caused by damaged plates or internal corrosion.
* Parasitic Drain: Even when the car is off, there's a small electrical drain from various systems (clock, alarm, computer memory, etc.). If this drain is excessive (due to a faulty component or a short somewhere in the wiring), it can deplete the battery overnight, even a new one.
* Alternator Failure: The alternator is responsible for charging the battery while the engine is running. A malfunctioning alternator won't recharge the battery, leading to it running down quickly. This is another very likely cause.
* Voltage Regulator Problems: The voltage regulator controls the alternator's output. A faulty regulator can cause overcharging (damaging the battery) or undercharging (not recharging the battery sufficiently).
* Corrosion: Corrosion on the battery terminals can impede current flow, preventing proper charging and leading to a loss of charge.
* Damaged Battery Cells: Individual cells within the battery may be damaged or dead, preventing the battery from holding a full charge.
To diagnose the problem, you'll need to:
1. Have the battery tested: A local auto parts store can usually test the battery for charge and cranking amps to determine its health.
2. Test the alternator: This requires a multimeter to measure its output voltage while the engine is running. A low output indicates a problem.
3. Check for parasitic drain: A multimeter can be used to measure the current draw from the battery with the car off. A high drain suggests a faulty component or wiring issue.
4. Inspect battery terminals and cables: Look for corrosion and clean them if necessary. Check for loose or damaged cables.
It's highly probable that a combination of battery age and a problem within the car's charging system (alternator or voltage regulator) are the culprits. Replacing the battery is a good starting point, but further investigation is needed to prevent the new battery from experiencing the same fate.
