I have been using the Aerovoltz Li-Fe battery for 3.5 years. It has been great; no need to trickle charge it-it holds a full charge for 2 months (I have heard they will hold charge for a year or more). A full 10 lbs lighter than a gell cell. I will be replacing it one of these days with the newer EarthX Li-Fe battery with built-in cell balancing and over-voltage protection. There are some cons to these type of batteries: when they run down it happens quick without much warning; some folks are afraid of fire but the Li-Fe is much safer than the Li-Ion. I believe the positives greatly outweigh the negatives in my personal opinion.