Quite often a battery only lasts for as long as it is well maintained, but so far this is the best small battery I have tried.  It was definitely not inexpensive, but has been worth every penny so far.  I have tried quite a few and many of them only lasted 4 months.  The reason this one seems to work is that it holds a charge while sitting.  For a car, it is not an issue because you start it every day, but often recreational vehicles sit for long periods waiting for weather or waiting for you to get a day off.  If your battery gets drawn down too far, you cannot always save them.  This one has held its charge well.  The negatives are the price and that you are not supposed to use a regular battery charger to charge these. I am using a BatteryMINDer, but have only charged it once or twice in the last 3 years.