As title really. I looked at the one at Frosts and it was £26!!! I could buy a new battery every two years for that and negate the need for a Battery Saver!

lidl and Aldi have them regularly....tho not when you are looking for one prob.

I use a £4.99 one from aldi to suit a motorbike on my car, it's the imbedded plug type one and has been fine