"CCred68046" wrote in message
...
Um....ok, but why "dissimilar"? I'm curious about two different
batteries.

One is an old 1000 CCA deep cycle for trolling and the other is a new 420
CCA
starting battery. Switching them to the both position will cause the good
battery to be discharged by the weaker battery. The way it was described
to me
by a battery expert was "If you pour good milk into bad milk you have a
bunch
of bad milk".

Should not matter, as sonn as they are both the smae voltage, then no
current. Get a 1/2/both switch so you can connect both togehter, of both
are low and you need a little extra energy. Run the battery on 1 (starting)
all the time and add a battery combiner from West Marine (about $90) This
connects both together for charging when the voltage rises above 13.4V.
Bill