[Richard and Rhonda]

If you have had a cell go out in a battery it will cause all kinds of issues. It is possible when you hooked them up that the good battery was now shorting through the bad one.

Unhook all the batteries from one another, measure the voltage of the individual batteries. Wait 24 hrs and measure them again. That will usually show you the bad one.

I'm a dang chemical engineer, and I can't ever get the hydrometers to work accurately, so I don't bother with the cell by cell measurement. If one cell is bad the battery is toast anyway, and it will usually not hold a charge.

I also agree that installing a multi stage charger is cheaper than continually cooking batteries.