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1979 Continental Sedan Battery Drain

Bill -

I have a 1979 Lincoln Continental Sedan and this last year it seems to be draining its battery while it is sitting. I put a meter on the battery and it reads 12.7 as soon as I turn off the car. While it is running it is 13.8. I know newer cars the alternator produces 14.3, but not 100% sure on this one. It seems to take about an hour to drain it down to 12.2 where at this point the starter will only click, which I expect. If I boost it at this point, it fires right back up. I should notice observations at this point. A new behaviour is; I can wind down the windows and use the radio with the key off as well as pop the trunk & run the heater blower. My guesses at this point are: a relay somewhere or the alternator regulator is bad. I can continue to drive the car and I just uncouple the negative when I stop for any period of time. Any thoughts or advise would be appreciated as I'm grasping at directions to search.

Tom

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Hi Tom -

If your readings are correct, 12.2 volts at the posts of a good battery is more than enough to crank and start that engine. After turning off the engine it is not abnormal for the voltage to drop somewhat from 12.7. I suspect that the battery is aged or faulty and therefore a load test at an automotive electrical shop would be necessary to verify the battery condition. If you suspect the alternator or a regulator, they alone could be disconnected during a period of non use to prove or disprove an internal electrical draw. Of course, all other cable connections must be correct and in good order.

After the above electrical draw is corrected and the newer accessory power problem that you have described still exists you will need to trace that circuit with the use of the proper manual and wiring diagrams. This type of diagnosis is best done in a logical sequence by a technician with this type of electrical experience.

Sincerely,

Bill