Battery size?

If the cables look old and you don't know when they have been changed, or if, I'd change them anyway. Just good preventive maintenance.

Load testing can be done on the car and does not require carrying the battery some where.
Once again take out your $10.00 meter (or free) and check the batter voltage, that 12.6 or close to it should be there before the engine is started. Then turn on the heater blower motor, the head lights and put them on high beam and any other electrical load you can think of that is easily done by turning on a switch and hook that meter back up. If that 12.6 is heading for the seller and the battery connections are good, then the odds are the battery is looking at the end of it's life. But if they are holding fairly steady and you have some help, once you check the voltage try to start the car while the meter is still hooked to the battery and all those things are still on. The car should start and the battery voltage not be under 8 volts while it is trying to.

And as to the battery connections? Remove them and clean them. Those from the battery and the other end, the one bolted to the engine and the other to the starter.
And while you are down there doing that verify that the large gauge wire that goes from the engine block to the body right around the passenger side engine mount is there and in good condtion.

[/QUOTE] That's provided you have the load tester with you.   and battery voltage should not be under 9.6 volts. 8 is way too low.[/QUOTE]

You don't need a load tester, there are plenty loads built into the car and you use them. And the voltage you get will depend on the load used at the time it is being used and 9.6 is only one value that may show up depending on the load, but if it is lower than 8 no mater what the load is suspect the battery. I suspect but don't know for sure but 9.6 might be a number a specific piece of test equipment has as a result. When using the loads a car has available to be used, 8 volts is a perfectly legitimate number to go by.

Edited by uncljohn - Nov/09/2015 at 2:37pm

When you measured 10.8V, was that while the engine was cranking? If you measured while the engine was cranking, that sounds reasonable to me. If you cranked it over a couple off time, then stopped to measure the battery, the battery seems weak and barely able to hold a charge. Get it load tested to be sure.

Just an update, I took the battery out and had it load tested at Batteries plus. It checked out to be very good. I'm going to put new cables on, as the old ones are the type where you cut the cover off the cable and put it under metal clamps. I'm going to get the one piece type. If it still runs the battery down I have to assume its the starter making it turn over slower than I think it should.