This 2001 Buick Park Avenue came in with multiple complaints. Some of which were various dash warning lights would come on, the gauges would stop working, the power door locks would cycle intermittently and the battery would go dead. I asked the customer specifically if the clock on the radio would reset and was relieved to hear the answer was yes. Experience has taught me that if the clock resets that there is likely to be a major power or ground circuit interruption. I did a quick voltage check at the battery with the engine running. A flat 12 volts indicated there was a problem.
I checked the voltage at the junction stud connection on the underhood fuse box and it was what I should have expected with a running engine. A nominal 14 volts.
It seemed to me that with normal voltage at the fuse box stud, low voltage at the battery positive terminal and an obvious junction point in between, that the junction point may be the location of the problem.
At first glance there did not seem to be a problem at the junction point. No arc or burn marks were present.
A gentle wiggle of one of the cables indicated that it was indeed loose. Notice that my fingers are back on the insulation and not on the terminal itself. Experience is a mighty fine teacher.
I decided to take a temperature reading to show why I did not just carelessly grab the terminal. The engine had only been running about three minutes when I took the reading with my infrared heat gun. Amperage plus resistance equals heat and a lot of it.
I turned the engine off and let the connector cool down for a while. Then I took the connector apart, wire brushed the terminals and tightened the nut securely. I took another temperature reading. Roughly two hundred and sixty degrees cooler than before.
At start up the battery terminal voltage was 13 volts. It did not start coming up very quick so I turned the engine back off and connected a battery charger to the car.
After all alternators are designed to keep a fully charged battery fully charged. They are not designed to recharge a discharged battery.