I just bought a new 12 volt Deep Cycle and Marine Group 29 Battery and I typically charge it at home before and after trips with a Schumacher Speed Charge battery charger/maintainer. It has two charge rate settings "Power Sport - 3 amp" and "Automotive - 12 amp". I am wondering which setting is better for the battery and will give the longest use? I think I remember reading somewhere that ideally you should charge at the rate closest to the discharge rate? Or does it just really not matter that much? It does charge differently as if I charge the battery to 100% on say the 12 amp setting and then unplug the charger and then hook it back up and charge at the 3 amp setting it will charge again for a little while before reaching 100%.