The Westco battery I have fitted has CCA of 400A and whilst it did not start instantly this morning did start quite easily. This battery is essentially the same dimensions as the Banner battery. However there is plenty of space above the battery so a wider battery could be accommodated by positioning it higher than the existing, this gives many more options for choosing a battery with greater capacity. I did not go this route because I thought the Westco would be direct swop but as it turned out was a few millimetres wider and required an adaptor making anyway.
This Varta would seem a good replacement for the original as fitted by
atalante83. Same footprint, in fact 1mm narrower according to spec although 60mm taller, so will probably require a strap mod as well as different terminals or adapters.
A respected brand with 33% greater capacity for under £39 delivered in the UK.
