Quantum Xcell very good for me, been on my car over 10 years, still fine, though i think this winter will prob kill it off! You need to top it up with distilled/de-ionised water. Available from lots of places i think. Car accesory shops will cost more, i got mine from in-excess. Take off the cap(s) from the top of the battery and top up with this watter to just over the plates in it.