Ford Mondeo Dies When Pushing Start Button

So has anyone experienced anything like this before?

I have had my car for five years and nothing like this has ever happened before.

I recently unlocked the car, the door locks open, the mirrors extend, the interior lights come on, the dash display lights up and the radio works. Everything was normal

When I pushed the start button the car died completely. The dash display went dead and nothing worked.

I thought that the battery was flat and stuck my CTEK charger on but it would not work. When I switched on the charger there was lots of clicking coming from the fuse box next to the battery.

I took the charger off and measured the voltage across the battery. It was 2.2 Volts.

My CTEK charger won’t work if the battery voltage is less than 2.5V

I then took the battery out of the car with the view of replacing it. I checked the battery volts again and was surprised to measure 12.6V. I then charged the battery up with my CTEK and left it for 24 hours. It held the voltage at 13.5V until I put it back into the car. Once connected the battery voltage dropped to 12.6 V

The car then started up without issue. I had to reset the clock and unlock the radio. There were no warning messages. I then took it for a 30 mile drive without any issues. When I got back I waited ½ hour and measured the battery voltage which was 12.6V

36 hours later I then measured the battery voltage at 12.43V

I didn’t want to take any chances so I left the battery on charge and then took the car into my local garage. They tested the battery and said that it was OK. They also checked for error codes and said that there were none.

They did say however that it may be prudent to change the battery based on what I told them. I’ve since ordered up a new battery. The battery installed is only 3 threes old and was fitted by Ford.

What I don’t understand is why I measured the voltage across the battery at 2.2 volts and then once the battery was out of the car I measured 12.6V.

I have not tried to start the car since as I want to monitor the battery voltage to see if it drops excessively.

I am guessing that either that battery is duff or perhaps there is a new parasitic load problem.