Bad idea sealed batteies not good for your purpose see http://www.sterling-power.com/support-faq-2.htm
extract below
Fast charging costs water, i.e. if you want to charge you batteries fast, don't touch a Sealed/Gel/AGM etc with a barge pole. Fast charging will result in a certain % water loss from the battery. If the battery is sealed the water loss cannot be replaced. REMEMBER FAST CHARGING AND SEALED/MAINTAINCE-FREE ARE A CONTRADICTION OF TERMS. You may not like this, but tough, it's the way it is.