Tuesday, November 19, 2013

Forward Battery bank.........

I have been undecided on the need for a forward battery bank for some time.  I will have a windlass (Lofrans Tigres) and possibly a 4HP Vetus bow-thruster installed.  I finally decided to bite the bullet and install two group 24 batteries (79AH each, installed in parallel)  in the port locker in the vee-berth.  I have connected the two banks (house and forward) with 1/0 cable via the Mastervolt DC Distribution 500. This cable is fused at both ends and has a switch at the forward battery end.  Most of the time this switch will be off.  The forward bank will be maintained by a Xantrex Echo Charger.  This will ensure that the forward bank is charged anytime a charging source is charging the House Bank.

My logic is as follows.

1.  The windlass needs a battery bank of a minimum of 100 AH - check.  Its max draw is 125 Amps.

2.  Under normal windlass operations I will switch the connecting switch ON.   This will allow the alternator/house bank to pass this amperage to the windlass should it be needed.  The 1/0 wire is far in excess of the minimum required for a 30 ft (round trip) of 125 Amps.  This setup will permit almost continuous use of the windlass.


The bow-thruster is another ball of chalk;

1.  Interestingly it only needs a min battery bank of 108 AH.  It draws 350 Amps for a max of 4 mins.  In reality you use it far less that this or you are doing something wrong.  I would have to connect both banks using 3/0 wire to facilitate recharging from the house bank.  This was a non starter.

2.  Under normal bow-thruster operations I will have the connecting switch to OFF.  The bow-thruster will ONLY operate off the forward bank.  This is acceptable in my book.  Any current used will be recharged from the Echo Charge once a charging source (e.g. Alternator/solar/wind) is available.

All opinions welcome, speak now or forever hold your peace.


paul kessinger said...

I have basically the same system with smaller gear - Lewmar 1000 windlass, Vetus 55, Group 27 battery.

Works great. Can't even see the house batteries budge during normal windlass/thruster operation. I believe you will have the added benefit (if your switches are like mine) of a spare battery bank up front if anything goes sideways with either the house or starting banks.

Get the thruster. I don't have to take a blood pressure pill before docking anymore, and it is at-the-ready emergency steering. My Vetus just got us without fail through 145 locks on the Loop.

Rhys said...

Sounds reasonable to me. I'm skipping the 1/0 cable run, however...at least so far. I prefer to echo charge one battery gradually because I have so many charge sources (alts, four 135W panels, a 400 W wind genny, and two Hondas if it's dark and calm!) that I should be close to 100% all the time. Also, the Lofrans is manual and I'll have a teenaged boy aboard (insert whip crack here). So the general idea is to "pre-flake" chain on deck, pay out until bottom's hit and then back the sail. Sail/motor up to the anchor when leaving and only power in the vertical chain plus anchor. That's kinder to the gear and, while slower, makes it easier to tidy and clean the chain while bringing it aboard.

I too see the "forward battery" as an isolated (I'll have a full disconnect for it) emergency start/house should I get a major FUBAR in the house and start bat banks in the middle of the boat.