Paul, Current capacity or ampacity of the wire is a great consideration for the charge efficiency of the solar charging system. Minimizing line loss is critical as well as optimizing/matching the charge voltage (voltage felt by the battery) and the panel output voltage. A duplex wire as you suggested would benefit from being as large as reasonable achievable. For the preexisting windlass I would not be surprised to find that those wires are 0 or 00. 6awg seems to be on the small size. With heavier gauge wire already running between the battery and the bow, the losses would be insignificant.
A 0 gauge wire carrying 12v at 20amps for 50 ft would have 1% voltage drop. 1 gauge wire at 15 amps would only lose 1% and 3 gauge wire would carry 10 amps with 1% drop. Don is effectively suggesting the creation of a remote battery bus. Without proper bus bars it would not be "wrong" to just attach the new circuit with a ring terminal to the line (hot) side of the windlass switch and the ground side of the windlass. There are ABYC provisions for attaching more than one ring to a stud. Use an inline fuse (automotive style would be fine) to protect the new circuit. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Thu, Apr 4, 2019, 12:21 PM Dreuge via CnC-List <[email protected]> wrote: > I think you would be better off running a separate duplex wire back to the > controller near the batteries. It’s a long run, so the size of the wire > will depend on the current. > > Let’s assume a 25 ft length of duplex wire, then that's 50 ft of wire both > ways. The tables for a 3% voltage drop recommends at least 6AWG for 15 > amps. That’s good for about 250 Watts. Since most panels produce 16-20 > Volts output, you gain by having the controller near the battery (higher > voltage means lower current through the wire resulting more watt > capacity). Having the controller up front would results in a 3% voltage > drop of the regulated voltage making battery charging much less efficient. > > - > Paul E. > 1981 C&C Landfall 38 > S/V Johanna Rose > Fort Walton Beach, FL > > http://svjohannarose.blogspot.com/ > > On Apr 4, 2019, at 11:30 AM, [email protected] wrote: > > Message: 3 > Date: Thu, 4 Apr 2019 08:39:54 -0600 (MDT) > From: DON JONSSON <[email protected]> > To: [email protected] > Subject: Stus-List Dual purpose of windlass electrical wires? > Message-ID: <[email protected]> > Content-Type: text/plain; charset=us-ascii > > Hi All > > Sort of a weird question, but hopefully someone has some insight. > > We have been struggling with where to put solar panels on our C&C 34. We > now think that we will get a couple of flexible panels and leave them free, > at least for now. The plan would be to put them out on the fore deck when > at anchor in the beautiful BC sunshine. What we don't want is wires > running all over while they are sitting out. So we thought a couple of > plugs mounted in the chain locker with the wires running back to the > battery inside the cabin. That way when stopped we would place the solar > panels in the most appropriate spot on the fore deck with short wires > running forward to the plugs inside the anchor locker, and then long wires > running inside out of view to the batteries at the back of the boat. > > So there are already a pair of very large cables running from the windlass > to the batteries. Is there some way to leverage those cable for connecting > the solar panels. Just inside the front of the Vberth is where the cables > connect to the windlass controller. We could connect the controller for > the solar panels there which would then connect directly to the batteries, > through a breaker, and the ground bus bar via the existing cables. Or > possibly put the controller back by the batteries? > > Comments? > > Thanks > Don Jonsson > Andante, C&C 34 > Victoria, BC > > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
