1996 Mitsubishi Eclipse Repair Question
Are you saying the engine starts, then the battery drains in 20 minutes while it's running? That indicates the generator isn't recharging the battery. Use an inexpensive digital voltmeter to measure battery voltage while the engine is running. It must be between 13.75 and 14.75 volts. If it is low, suspect the generator or voltage regulator.
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Compare the voltage between the battery terminals and also between the alternator main post abd ground. You could have a bad link between the alternator and battery.
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