[C38] battery box rebuild

[phil]

>It would seem you plan to put in a lot more capacity than your useage suggests you need (unless you plan on carrying a golfcart on your foredeck).  Letting a battery slowly drain over a period of days is bad for it.  It would probably be better to work the recharging issues so that all batteries are topped each day.  This gets maximum life from the batteries.  I have a comparable set-up on my boat in terms of consumption  (I also run a 150w inverter for laptop navigation, and I have a tricolor light, so running lights are more like 6 amps for me. No fridge, but the admiral runs the stereo twelve hours a day).  I have two kyocera 130 panels, an ASC20 controller, 2 27 series house batts, and 1 31 series start/deep cycle.  Two of us cruised the Bahamas for 2 months with no problems.  Had to start the diesel twice because of batteries.  Used a total of 8 gallons of diesel during the cruise. Both times I had to start diesel were when the autopilot dropped offline an hour before dawn on multiday jaunts.
 If you don't think your solar is going to completely top your batts up by sunset, run your diesel early AM to bulk charge, and let the solar provide "accept" current.
 The one exception to this that makes sense is if you are a weekender and have "free to me" grid power and the better sort of ac powered charger.
 All in all, I would rather kill a pair of batteries in two years and replace them than carry four and replace them after four years.
 And one conservation tip- If you have a two gallon holding plate fridge, you can set the compressor up to run on high speed while the solar is charging (or any other source of charging is opperating) and switch to low speed at all other times.  This greatly reduces the nighttime load which is what shortens the life of batteries on a solar setup.

-- 
Phil Sweet

Cat38 158 Our Tern
Key Largo, Fl.


> Message: 3
> Date: Fri, 20 Mar 2009 13:03:10 -0700
> From: Les <hlhowell at pacbell.net>
> Subject: [C38] Battery box rebuild
> To: Listserve at catalina38.org
> Message-ID: <1237579390.14214.21.camel at localhost.localdomain>
> Content-Type: text/plain
> 
> Hi, everyone,
> 	I am finally ready to do my rewiring project.  The first thing I want
> to do is modify the battery box to accept 4 golf cart batteries.  I seem
> to remember that someone said they had already done this, so I am
> looking for pictures/process to help me avoid mistakes.
> 
> 	I think from my measurements that the box needs to stretch about 2.5"
> port to starboard, and I can rip out the 2" or so divider, and replace
> it with about a 3/4" inch one in that new dimension.  This would move
> the inboard battery about 3-3.5" beneath the current seat edge, so that
> would probably have to change as well.  I think I could probably just
> cut the new desired dimension out of the top, remove the large end of
> the box and extend it 1.5".  However this may encounter some issues as
> it approaches the truncated end of the settee by the galley cabinet.
> 
> 	The center divider could be cut out, and fiberglass tape used to repair
> the box bottom, with a new divider tabbed in place by the same method.
> Probably 1/2" marine ply covered with a layer or two of cloth or tape.
> The outboard end would be stretched 1-2" and re-attached with glass tape
> as well.  This would give me a box that measured about 22.5" 
> by 16" and the batteries are 10" by 7", so they would fit with some room
> to spare.  Nylon straps across the battery tops would hold them in
> place.
> 
> I plan to add bus bars as well to make the connections cleaner.  I no
> longer have a batterycharger there because I have two 65Watt solar
> panels to maintain the batteries.  This gives me a charge current at
> just under 9A peak, and here in CA, this gives me about 50AH/day.  This
> seems to be enough to let me run the refer with no impact.  At anchor I
> would have to run the engine about 4 hours every 5th day to replenish
> the house draw (we're relatively frugal on power).  We use about 4
> lights during meal times (6A for 2 hours) and 2 lamps for reading (3A
> for 3-4 hours).
> 
> Under sail, the autopilot draws about 1.2A, so it would deplete the
> battery in about 50 hours with the instruments and refer running at the
> same time, so about every other day for 4 hours when under sail and auto
> pilot full time.
> 
> 	My total instrumentation is a knotmeter, a depth sounder, GPS, VHF, and
> Autopilot.  The knotmeter is very low drain, the depth sounder about
> 0.25A average, and the GPS is about 0.75A in daylight, a bit higher at
> night.  The vhf draws about 0.25 in standby.  Thus my total draw is
> about 2.25A continuous underway under sail, and add about 2A for running
> lights at night (we are coastal sailors and don't do much night
> sailing).
> 
> 	My engine has a 35A alternator which seems adequate (the batteries
> typically drop to bulk at about 12A after 20min run time.)
> 
> So how does this measure up to those with more experience?
> 
> Regards,
> Les H
> 
> 
> 
> 
> 
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