I went to start my 230 SL yesterday and it cranked over 3 times with out starting. Then it acted like the battery was low and would barely turn over. I went and got a new battery today and the car started right up so I drove 11 miles and shut it off at my parents house. The car ran fine with no problems at all on the highway and in stop and go traffic. The car acted like it had a dead battery when I went to restart it the same as yesterday with the old battery. It will not start even with jumper cables. Testing the battery it shows 12.86 volts with the cables off. What would cause this sudden problem after trying to start the car? I had to have the car towed back to the house. This is the first major problem in 9 years and 11000 miles...