Classic/Antique Car Repair: Battery drain?, cigarette lighters, pontiac parisenne

Question
Hi Dick
I recently bought a 64 Pontiac Parisenne 230 6 cyl standard.
It worked fine,and I drove it every day no prob.Today,after not driving it for a week I needed to boost it.I checked the battery after and it tested good.
Do you think there could be a drain on the battery or something else? How would I test for this? (I am not a mechanic.)
If it is a drain,how do I figure out what it is? It has a radio that doesnt work,the washer fluid pump also doesnt work.Could this be the problem? Thanks

Answer
Yes, this is probably caused by a battery drain.  The only way to track this down is to get someone with some electrical equipment and experience to help you.  

The process is to connect a meter in series with the battery positive cable connection, set the meter to indicate the amount of current drain, and then start pulling fuses and disconnecting electrical items, one by one, checking the meter to see if the drain has stopped after each fuse  or other electrical load is disconnected.  Finally, you will disconnect something and the drain will stop. The last item disconnected is the culprit.

I cannot begin to guess what it will be - it could be anything from a light left on (inside the trunk, glove box, or under the hood) to a bad clock, to a bad horn relay.   Since it runs down with the key off, you can eliminate all the key operated devices - that narrows down the candidates to things that are on without the key. The horn relay, lights and the cigarette lighters are the most likely candidates, plus any non-factory device that has been added to the car since it left the factory that is not controlled by the key.

Since the radio and the windshield washer go on and off with the key, these cannot be the culprit unless someone has modified the connections.

If the meter does not indicate any current drain, yet the battery still goes down by itself, you may have a sulfated battery, regardless of what the battery test told you. The way to sort this situation out is to park the car for a week or more with one battery cable disconnected. If the battery still goes down with nothing connected to it, you know the battery has failed.

Dick