H33C Electrical
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Battery upgrade.  In looking at my battery situation and knowing how many gadgets I intend to have in the coming months, I know I need to make an adjustment from the two deep-cycle batteries (dated Feb 2005) that came with the boat.  So I used Nigel Calder's method for determining my daily needs to size the battery banks.  (if you do not own a copy of Nigel's book, I highly recommend it: http://www.amazon.com/Boatowners-Mechanical-Electrical-Manual-Essential/dp/0071432388/ref=sr_1_1?s=books&ie=UTF8&qid=1332177106&sr=1-1) If my calculations are correct, I would need about 100-125 Ah per day.  The properly sized house bank would then be set at 300-375 Ah in capacity.  Adding 20% fudge factor as Nigel calls it, puts me between 360-450Ah of capacity.  Now actually using that much and putting that many Ah back in is a second part of the electrical problem I will be working on, but first lets build in the capacity from the start.  So I went down to my friendly SAM's club and bought 4 Duracell EGC2 6 volt golf cart  batteries with 225 Ah capacity each.  Hooking two in series gives me 12 volts with 225 Ah, and then putting two pairs in parallel, I get my 450 Ah capacity and a 12 volt deep cycle system.  Now what to do with 4 golf cart batteries , each weighing 68 lbs?  Here is what I did on my H33C.


The first thing is to determine the approximate location for where they should go.  I know the original batteries went over the shower sump, but the boxes I needed to house the batteries would stick up over the chart table (not a good thing).  I cleaned out the sump, and lowered the support brackets as much as I could without interfering with the bilge pump output hose.  This was about 1.5" on Arpeggio.  In the picture of the cleaned out sump-well you can see the two screw holes on the side of the well just above the new aft 1x4 PVC support board.  Those two screws went through a 1x1 piece of teak and supported the aft end of battery platform.  With the supports lowered, I was below the chart table but still too cramped to get the second box in place without tipping it over.  So I took everything home and setup a mock sump well and engine enclosure (already made the engine enclosure cabinet frame and walls) and determined that I needed to lower the whole thing by another 1.75".  hmmm.  (BTW - I have a new Automatic Rule 750 GPH bilge pump to install in the well.)

In looking at the Pro-Fill hydration system purchased, I determined I really only needed 1.25 inch clearance from top of battery to the bottom to the bottom of the battery box lid.  So I cut each box down so that the space from the bottom of the lid to the battery was exactly 1.375 inches (1/8 inch to spare).  In so doing, I trimmed about 2.5 inches from the stacked height of 28 inches; down to 25.5 inches.  This gave me the clearance I needed.  I set the second box back from the front edge of the lower box by 1 inch (the back of the top box was back now even with the front edge of the access opening on the port side), but this may go back a little more once I run the cables and hydration tubes.  The important part to this placement is making sure my access door can still close.  The internal dimensions for each box are 14.25" wide x 10.375" deep x 11.625" tall.  Since each lid has a 1/4" rabbit edge, this lowers the interior height to 11.375".


I painted each box (inside and outside) with Zinsser Mold Proof Interior paint tinted to the same color as Cream Kiwigrip. All interior paint for this boat will be the Zinsser mold proof stuff.  I will use it in the head to freshen the wallpaper and engine compartment's unpainted/unstained/non-varnished wood. (http://webapps.easy2.com/cm2/flash/generic_index.asp?page_id=35873803)

Looking good!  All wiring inside and outside of the boxes is 1-AWG.

After painting, setting batteries in each box, I connected each pair with a 5" connector.  I then routed the positive lines to the 225Amp fuse block and the negatives to a ground bus terminal.

The Pro-Fill tubing can clearly be seen here with the gallon of distilled water next to the column.  The hand pump is not in the picture (I do have it though).    Everything fits nicely and is ready to go into the boat.  I secured the top box to the bottom and the top lid to the top box with simple hook and eyes.  Because the lids of each box were rabbetted and set into their boxes, they will not leave their box even without the hooks.  I tested this to about 40 degrees (about the balancing point).  The hooks just help to keep them together.  I will secure the boxes to the sump supports when I get them to the boat and before I load them with their battery pairs.  I picked up a carrying handle from Batteries Plus.  The clerk said they don't normally sell them and gave me one for free.  How do you like that?


With the cabinet remade and assembled on the boat, she is ready to receive her new house batteries.  Note the two switches; house and starting battery isolator switches.  These are brought together by a smart charging relay under the charging relay.

Above the house battery isolator switch is a 4 pole bus for taking the battery chargers and other non-switched devices like bilge pumps, VHF-radio, stereo memory, etc...  The back of the crank battery switch has just enough clearance for between the engine mount and switch cover plate (about 1/4").  I inserted closed cell foam here to eliminate any potential vibrations.  After muscling the batteries up and into the boat, I loaded them in their boxes and set them in place.  The hard part was lifting the upper battery box and setting on the lower box.  However, taking the map table (the part that slide) out, it was actually quite manageable.  However, it would have been a lot easier with two guys for sure.

  The final assembly is shown to the left.  The ladder is mounted to the panel/door that sits in the Mahogany frame I made.  The ladder seems solid enough.  It is certainly easier getting in and out of the boat having one.





I have a Blue Sea ACR controlling the charging of both banks.   The ACR is mounted under the pilot berth in the compartment with the battery charger and main circuit breaker panel.  I follwed the instructions for the most part.  However, the ground line is 14 AWG (instead of 16 AWG) and I used the house line post (the one on the left as a bus to connect the DC main (6 AWG).  The cranking battery line is 4 AWG, and the 5' run from house switch to the ARC is 2 AWG.

The wiring or house and cranking batteries are detailed in the Blue Sea resources; article 57 reproduced below.  The original is on the Blue Sea site: http://bluesea.com/viewresource/57.  Also, see http://bluesea.com/viewresource/58.


Automatic Charging Relay - An Alternative to Multiple Output Charging Systems

What do you do when the number of battery banks on your boat is greater than the number of charging outputs from your system′s battery charger, and you want to provide a charge to all batteries? How do you design a boat electrical system that charges two battery banks without adding the cost of a dual output charger? Instead of upgrading your charging system, or installing a system with multiple outputs, install an automatic charging relay (ACR). The cost of a charging system with multiple outputs is considerably more expensive than one with single output, making the installation of the ACR a less expensive option.

For example, consider a typical marine electrical system with two battery banks, a battery charger with one output, and an alternator. To charge both battery banks from your single output charger, connect the ACR between the battery banks. Connect the alternator to charge battery 1 (start battery), and connect the charger to charge battery 2 (house battery). When the charger is charging battery 2, the ACR will combine battery 2 and battery 1 for charging. When the alternator is charging battery 1, the ACR will connect battery 1 and battery 2, and both batteries will be charged. With the installation of the ACR, when at dock and plugged into shore power, the charger is supplying a charge to both battery banks; when the engine is running, the alternator is charging both battery banks.

Similarly, if you are adding an auxiliary battery to power a windlass, you can connect the auxiliary battery through an ACR to a battery bank that is attached to a charger. In this way, you are able to charge an additional battery bank without upgrading the charger to one with multiple outputs.

The ACR automatically connects batteries during the charging cycle and disconnects them under discharge.

When combined with Blue Sea Systems Dual Circuit Plus™ Battery Switch (PN 5511e), the SI ACR model fully automates the charging of two batteries. The combination of the Dual Circuit Plus™ Battery Switch and ACR provides a practical and less expensive solution to manage:

  • Isolated battery circuits
  • Emergency parallel backup operation
  • Automated charge management

Simply turn the battery switch to the ON position when arriving on the boat, and turn it to the OFF position when leaving. You no longer have to worry about which batteries are charging or discharging.

Before replacing your charger or inverter/charger, consider the benefits of an ACR; and for a fully automatic system, add a Dual Circuit Plus™ Battery Switch.