[neilmcd]

I have a pair of 6V wet cell golf cart batteries (for house power), a 12V wet cell battery (for starting) and a Zantrex 3 stage smart charger on my sail boat. The 12V wet cell is buried in the bottom of the lazarette, where it is very difficult to access, so its fluid level tends to get neglected. A clear case for switching to an AGM for the starting battery!

But wait a minute.......the optimum charging voltage for a typical AGM is different to a wet cell. My Zantrex even has a switch to choose the battery type. What to do? One theoretical option might be to fiddle around with adding an extra resistor on the charging side of the battery that prefers the lower charging voltage.

Yesterday a battery sales guy told me that some AGMs (including his) are far more tolerant of wet cell charging voltages than others, something to do with the design of the lead plates. Was this just a sales pitch is there a generic difference in some AGMs that I need to know about?