Upgrading Electrical & Power aboard Sea Dragon


Upgrading the Power and 12 volt electrical system on board Sea Dragon

Over the years I have upgraded the systems on board Sea Dragon increasing the need for power. Early on I increased the hose bank from one group 31 (105AH) to two (2) Group 31 batteries for a total house bank of 210 AH plus a starter battery, a group 24. Time has shown that this simply is not enough. At the same time I have worked to try to fit everything into the original 1981 Pearson DC panel

So it is time to bite the bullet and add more power and circuits.

The plan is as follows:

1. Rip out the current battery box & replace it with newer larger box
2. Expand the house bank from 2 each 12 volt Group 31 (210 AH) batteries with 4 each 6 volt Golf Cart batteries at 215 AH for a total of 430 AH @ 12 volts. 
3. Replace the group 24 starter battery with a Group 31
4. Replace the 1 - 2 or Both battery switch with a Blue Sea Systems e-Series two (2) battery switch
5. Add a Blue Sea Automatic Charger Relay (SI-ACR) 12/24 volt 120A
6. Expand the 12 circuits 
7. Add a 12 volt plugs at the Nav Station, Saloon, Cockpit, and V-Berth.
8. Install a battery monitoring system - Victron Energy BMV-702
9. Replace the 35 year old kind-a-smart 30 amp battery charger with a Sterling Power ProUltra PCU 1240 40 amp charger


Step 1 - Start collecting parts

The center piece of the Battery Upgrade is to replace the older 'Off-1-2 or Both' switch. I chose the Blue Sea e-series switch that isolates the starter battery from the house batteries. From time to time when starting the "Red Beast" after a long sail the voltage drop was enough to shut down the electronics on board - not a good. The e-Series switch is design so that the battery banks function separately or as a single bank if needed.
Step 2 - Tear out the Old

I broke out the old reciprocating saw and began cutting the original box down.

The plan is to build a platform to mount a battery box I constructed. The new box is larger than the base, so to provide the necessary clearances around and under the box I needed to raise the top of the base 1-1/2 inches. This was accomplished by adding a 1 inch oak spacer screwed and epoxy-ed into place plus the 1/2 marine plywood top/base.
It is important for me to to be able to easily remove battery box for maintenance or access. As you will see it is much larger than the current configuration.To accomplish this I used 5 - 3/8 inch stainless steel T-Nuts.

Step 3 Build a box
I built my battery box from 1/2 marine plywood screwed and glued - but this was not enough. I decided to lay a layer of 4 oz woven fiberglass to both the inside and outside increase the strength and durability. Without a doubt this step is over kill.
Fitting the batteries

I continued to fit and check throughout the build.
Finally to ensure a tight safe battery installation I cut wooden blocks and bolted each in place with 1/4" stainless steel carriage bolts.

To hold the lid on the box I installed two (2) battery hold down straps were added.

Finally a little wiring was added to produce a 12 volt battery bank. Custom made 2/0 cables from Tinned Marine Wire completed the house bank.

The ACR, fuses, and new switch were connected to complete the battery upgrade.
The original Pearson 1-2-both switch was installed using a 1/2 inch larger hole than the hole required for new switch. I made cover plate from a piece of scrap mahogany I had. It was stained to match the existing bulk head (OK the best I could). 

Finally the 6olb state-of-the-art 1980 Crown battery charger was replaced with a new smart Sterling Charger.
Now with all of these AMP-Hours I felt I needed to find ways to "spend" them. The best way to do this was to add various 12 volt receptacles aboard Sea Dragon. So I added six (6) 1-at in the cockpit, 2-at the navstation, 1-in the Saloon, and 2-in the V-berth along with a remote digital voltage read-out. 

(Pictures to Follow)
While I was expanding my electrical system I decided to consolidate and add a few extra circuits and consolidate things. A box was built to house 2-Bilge Pump Switch (blank space above the bilge switch); Hour Meter for the Westerbeke (the meter in the tach stopped working years ago); Bilge pump Cycle counter; and 3 additional 12 circuits.  

Front View

Side View


Return to Projects Page