I would very like to replace the lead acid batteries in my St90, SL90 and CT90 with an A.G.M. battery in each. I've been looking at the motobatt MBT6N6, which I know I've looked at before, and am pretty sure I remember it to be too tall (SL90 at that time. I will revisit the topic with the ST and the S. I'm sure I have read that 6 volt 5.5ah acts as a sort of voltage regular and that people have had problems going the AGM route. Motobatt has a MBT6N4 battery which is shorter than the 6N6 but I'm sure it's ability to act as a voltage regulator of sort, would be even less. So my question, and I apologize for my long mindedness, is, if I installed a voltage regulator, would it be safe to run the smaller battery?