Dwight;
As part of the refit for cruising I've added an Electra-San MSD and a 1000 watt anchor windlass forward, plus a dedicated battery to power them. I've installed a group 24 deep cycle of about 90 AH under the v-berth. Removing the big holding tank there made room for the Electra-San, a 9 gallon holding tank for when it is required in no-discharge areas, and the battery. The MSD needs 45 amps, but only for 2 minutes every time it runs. Maybe 10 AH per day. The windlass draws 45 to 60 amps for about 3 minutes or so, so somewhere about 5 to 10 AH per day. The group 24 DC battery should be sufficient. The relatively short wire runs let me use #6 wire for the two devices. Originally, I used a charging setup I had seen on a couple of cruising boats that have passed through the area. I have a small solar panel set up with a plug that connects to a socket I put under the wooden step up into my v-berth. The solar panel got laid on the foredeck with the wire running through the foredeck hatch. That has worked pretty well for the past couple years. What I have decided to put in for the long haul is a Blue Sea Automatic Charge Relay that will recharge the forward battery when the engine is running or the Xantrex charger is connected to shore power. The ACR will close when the forward battery is below about 11.5v and the voltage across the house bank is over 13-point-something volts; which only will happen when the house bank is charging. That will limit the current to the forward battery to something like 10-15 amps, and let me use #6 wire for the charging connection and still get low voltage drop. Putting the forward battery in parallel with my starting battery for charging would have given 45 or more amps, and required #1 or #0 battery cable - which would have been expensive and hard to route. It might also draw down the start battery with use of the head or windlass while at anchor. The saving on the cost of 60 feet of smaller cable more than offset the cost of the ACR and 50 amp breaker that are part of the wiring. I haven't given it much thought, but I suspect if you wire the forward battery to your engine alternator, you will need big cables. You normally use the windlass with the engine running to move the boat forward while taking in the rode and chain ( most windlasses are sized for this, not for pulling the boat forward against high winds and/or current) Since the voltage from the alternator will be higher than battery voltage, the amp draw of the windlass will take whatever your alternator will provide instead of drawing primarily from the battery. If you have a 55amp alternator as I do, you would need cable sized for 3% voltage drop over approximately twice the length of your boat - say 60 feet of #0 or #00 cable. Rick Brass Washington, NC From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of dwight veinot Sent: Saturday, April 27, 2013 4:16 PM To: cnc-list@cnc-list.com Subject: Re: Stus-List third battery next is an anchor windlass which will take a lot of instantaneous power but I intend to install a battery forward with charging from the engine alternator to do that.less low gage conductor wire required that way I think, but I am sure Rich will set me right on that Dwight Veinot C&C 35 MKII, Alianna Head of St. Margaret's Bay, NS
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