Optimas must be slow charged. Use a digital charger ( like battery tender ). They start charging at about 3 amps and go down to a 1.25 amp maintenance charge and automatically shut-down and start by the chargers system. I use a four bank charger and have all my boat and RV batteries on continuous charge (low amp) These chargers on an Optima can take 3 days to charge but will have it 100% afterwards. Not a solution to fast charge by no means. Optima Batterys are fiberglass celled batteries and will not charge by an alternator. I have my 03 Cooper S, I use occasionally for track an some driving wired so I plug in when I get in garage and unplug to use ( hard wired ) instructions are in box. I got mine for half price thru Amazon, but Advance, O'Reilly's, Autozone carry the single bank mini charger for $35-$45. Hope this helps.