987 Gen II - battery recommendations

[carbob]

For about a year I have had trouble with battery draining when prolonged lack of use.
Spent the weekend trying to sort it out. (I still suspect parasitic drain)
Using my CTEK charger, I got the battery fully charged ready to do some testing.
However the battery will not hold any charge. As soon as I try to start the car the voltage drops and nothing happens.
Tried a different charger - same result.
I presume battery is knackered - correct assumption?

Which battery to get?
I was looking at Bosch S5 110 as a good replacement.
However, has anyone got experience of the Bosch S5 AGM 115?
More expensive, but will it give better performance for a car that is only used occasionally?

Any recommendations?

[Porsche911R]

I use the S4 in mine.

[carbob]

Thanks.

Which version of the S4?
Model 100 72Ahr?

Cheers

[Porsche911R]

carbob said:

Thanks.

Which version of the S4?
Model 100 72Ahr?

Cheers

No idea it's under a cover also.

sounds about right though.