Hi Jim,
I have following this conversation thread over the past few days
and note your comments about overcharging. I have been through this
situation and settled on a solar panel charge controller. The unit I am
using uses a MOSFET to do the switching and a hefty Schotty diode
to isolate the battery. The 'charged' voltage is adjustable - in my case
it is 14.4 volts on a bank of SLA's. The hysteresis can be preset so that
the charger is not turning on/off every few seconds.
Gordon ZL1KL
Tauranga N.Z.