Battery question

[Surf01]

I have used the search engine but get a huge number of irrelevant hits. I have the winter pack in our 1996 3rd gen and the batteries are struggling at the moment to start it. Embarrassingly I had to use the Fiesta to start it yesterday!
What type of battery amp is recommended to be generally used if you have twin batteries. I have been made aware that both will need to be replaced at the same time. How can you tell the age of a battery?
Why do these things always happen when you are short on the readies? I will be looking for a battery that has a reasonable warranty and a good reputation at obviously a very reasonable price.

[steved]

A 069 and a 068 or the cheaper 089 and a 088 should do the trick.

[Albannach]

You need 750cca or above and always replace them as a pair.

There's a sticker, on the battery, that shows the initial charge date. Age isn't really a good barometer as to the condition of a battery though.

[highgun]

I got a set of Bosch 068/069 from Euro Car Parts (4 year Guarantee) for around £120 (15% off) a few weeks ago.