On Sun, 13 Nov 2005 19:58:04 -0800, jaykchan wrote:

I am thinking of adding a 24-volt trolling motor in the future. This
means I need to change the current batteries settings.

Currently, I have these two batteries:
(1) A 12-volt dual-purposes flood battery (group-24).
(2) A 12-volt deep-cycle flood battery (group-24) (the manufacturer
spec also says that it can also provide service for starting; sound
like its main purpose is to serve as a deep cycle battery; but I can
also use it for starting motor).
And I also have a battery switch that has 4 positions (1, 2, BOTH,
OFF).


You have an 18-ft open boat,right? No cabin, no 12VDC fridge, no anchor
winch, etc.? Let's not overkill things here.

First, are you SURE you need a 24VDC trolling motor? As you can see, it
complicates things greatly. Minn Kota has a nice 55-lb-thrust motor that
runs on 12V: the Max55T. I think it would push your boat fine, and will
pretty much run all day on a fully-charged group 24 battery (at
trolling speeds).

Second, if you decide on a 24V motor, you CAN buy a third battery and put
it in series with your deep-cycle battery: just make sure it's the same
type, etc. (yours is basically brand-new,right?) Use quick-connect
connections, and when you want to charge them, re-arrange them to
parallel. Then you can charge them either with the alternator or an
inexpensive charger (see your charger thread)

Lloyd Sumpter
"Far Cove" Catalina 36