I have used dedicated windlass batteries in the bow for the past 12 years, and wouldn't want to change the setup.
First, the extra weight question.
My setup consists of two Trojan T-105 batteries (total weight 128lbs) in a Blue Seas battery box
(maybe 8lbs) located under one of the V-berths in the forward cabin
. From these batteries, I run 1/0 cable 7' (14' round-trip) to the Lewmar
Ocean vertical windlass in the forepeak.
I simply don't believe that the 136lbs near the aft end of the forward cabin
makes any difference whatsoever on a 28,000lb displacement/9500lb ballast keel
cruising sailboat. At the very most, it's like having a SMALL crew member
sleeping in the V-berth.
The Wire Alternative.
My present wire run to the windlass from the windlass batteries in the forecabin is 14' round-trip. If I were instead to wire the windlass directly to the house batteries, the total run would be about 50' more, or 64' total. That's a long way for heavy cable, and a very long way if you contemplate minimal voltage drop for "silent anchoring" which I like to do.
Next, the rationale.
I like to sail. I like to sail up to the anchorage spot, drop the anchor, and spend the night. When conditions are right, I like to sail off the anchor. All without starting the engine. The T-105's give me ample power
to lower and raise the 200' 3/8 HT chain and 45lb CQR
FX-37 several times without need to start the engine or the generator
. How many times? That depends heavily on anchoring conditions: how deep, how much wind
, etc. But, suffice it to say I can go off for several days at a time without need to run the engine or generator
I installed an Iota
DLS-55/IQ4 charger in the forward cabin. This charger remains on all the time when at dockside. Underway or at anchor, if I need to recharge the windlass batteries, I can do so by powering the Iota
with either the generator or, sometimes, with the inverter while the main engine is running. The Iota provides a fast and full charge.
Two extra batteries to watch and, occasionally, top off with distilled water
(they have WaterMiser caps, so only rarely need watering). Need to pay attention to turn the charger on when AC power source is available.
The Bottom Line.
Dedicated windlass batteries and an AC charger located in the forward cabin have worked very well for me for twelve years.
A dedicated windlass battery bank in the bow isn't for everyone or every situation. But, it works very well for me.