I've had my 159 for four years now and the battery on the car is an Alfa Romeo battery so I presume original. (7 years old). The battery finally failed and I had to get another asap but what a performance.
Without mentioning any companies in Norwich and Yarmouth, I have visited 7 today and they all wanted to sell me different batteries of different capacities ranging from 80Amp hour with a Cold Cranking Amps of 800Amp right down to 60Amp at 650CCA.
When I stated that I required at least 90 Amp as per the original, you get the standard reply that the computer is always right, you don't need all that power, and the other company gave you the wrong information.
What a load of BULL.
Finally I visited an independent company in Yarmouth who checked on there computer and again confirmed the wrong battery size. But this time they measured the battery and came back with one for a Ford transit.
It was the correct size, especially the height, and most important it was 90Ah
SAE: 900 (CCA)
Length (mm): 317
Width (mm): 175
Case Height (mm): 190
Height (mm): 190
So what is the battery? Platinum Prestige 115E
Price £126 with three year warranty. RESULT.