[Al Skierkiewicz]

Well, AGM cells can theoretically be used and charged in any orientation. Gell cells are different, slightly. I recommend that charging take place with the batteries facing up for one reason only. Any water vapor will naturally drop onto the cell pressure seals during inverted charging orientation. If for some reason, the internal pressure causes the seals to open, some of that water will be lost. This is an extremely rare event. Just my way of optimizing battery life. Lost water translates to less contact between electrolyte and plate. Less contact relates to less available current which will lead to shorter usable life.