wrote in message
...
On Sun, 26 Apr 2009 14:57:04 -0700 (PDT), Tim
wrote:

anyhow, the Deep Cycle battery I had in my Pontiac had no problem
cranking over the 455 c.i.d. regardless of weather.


That is what touches on the difference. "starting batteries" usually
have better cold weather performance but they like to be charged
between starts.
Deep cycle batteries are probably better suited to the abuse the
average boater puts a battery through.

There are deep cycles, deep cycle starting batteries, and starting
batteries. The true deep cycle may not run a starter as they can not
provide the large instant amperage. Plates are thick and not as much
surface area. Deep cycle / starting are not as good deep cycle but have
more surface area and provide good instant current flow. Starting, have
lots of surface area, lots of instant current flow and thin plates. Deep
cycle them and the thin plates can warp and short out. But will turn over
high current starters. The thicker plates for less warpage and more empty
space under them, so sluffing off off of oxides due to lots of chargings do
not short out the plates. Most marine batteries in the local parts stores
are strating/deep cycle types.