Securing the House Battery Bank

One of the final components of re-locating the house battery bank was securing the batteries. 

Per Full River’s Specs each 6V battery weighs in at approximately 66 pounds.  Presently our house bank consists of four 6V batteries = 264 pounds.  We plan to expand the bank to six 6V batteries = 396 pounds.   Preventing this 400 pound mass from sliding around during normal conditions is critical to the long term health of our electrical systems.  Eliminating the possibility of this 400 pound mass from becoming a projectile in the event of a knockdown is critical to life and limb.

We designed the new battery box to fit snugly around the batteries.  The fit will limit side to side and fore to aft motion of the batteries.

Installing the new fiberglass over plywood battery box in the space under the center salon seat.

The new battery box is mechanically fastened, six ¼” counter sunk, flat head screws, to the Morgan 382’s internal glass unit (IGU).  The IGU is a structural member in the Morgan’s hull that provides strength to the hull and a mounting surface for the cabin sole.

Since we are two batteries shy of our desired six battery house bank, we constructed temporary filler to prevent the existing bank from sliding fore and aft.

Four 6V batteries plus the temporary filler in the new box.

Ok, this set up takes care of movement under normal conditions. 

Next we installed the system’s wiring.

House battery bank wiring complete.

We installed the wiring to allow space for bars to run across the top of the batteries.  Initially I envisioned having some stainless steel bars fabricated to fit across the space, but custom fabrication = $$$.  In the end we decided to keep it simple.

We purchased two 3’ long sticks of ½” diameter stainless steel all thread rod. 3’ was more than enough length to span the distance across the top of the battery box and thru both adjacent 3/4" plywood walls.

Using the 1/2" all thread rod to locate the hole on bulkhead aft of the battery box.

We began by drilling a ½” diameter hole in the plywood wall forward of the battery bank.  Running the rod through the hole and across the top of the battery bank aided in locating the position for the hole on the wall aft of the battery bank.  After drilling all the holes and test fitting the rods, we removed the rods and  cut them the proper length.

We sheathed the rods in 5/8" id hose. 

When re-installing the rods, we sheathed them in 5/8” id hose to prevent chafe or the possibility of a loose wire shorting out to the steel rod.

The ends of the rods are secured with nuts on both ends.

Nuts and washers installed on the ends of the rods under the galley sink (center, right below black water pump).

Nuts and washers installed on forward face, below the center salon seat.

We are confident the batteries are secure.  The next and final step in our battery re-location project is to fabricate a lid for the new house bank installation.

Please check out our Battery Re-location Photo Album for additional images and notes on this project.

Crimping Lugs onto Large Gauge Electrical Wires

Our recent installation of Pilgrim’s primary 12V DC wiring required the numerous large gauge, 4 to 00, electrical wires.  If you’re wondering which is the larger wire a 4 or 00, then check out our previous post – Let’s Talk Marine Wire, October 18, 2015.

Large gauge wire runs at electrical panel and starter battery.

Large gauge wire runs at house battery bank.

Here are a few things I picked up about crimping lugs onto large gauge wires.

Happiness is having the right tools for the job at hand.  The key for installing wire terminals on large gauge wire is having the proper crimping tool.   Unfortunately appropriately sized, quality crimpers are expensive and rarely part of the DIY sailor’s quiver of tools.  Fortunately I am currently able to borrow a great crimping tool with dies for crimping 6ga through 4/0ga. 

If anyone out can recommend a source for purchasing a quality pair of crimpers functional on 6 to 2/0 wire, then please share the info in the comments.

Tools and materials:  Clockwise from the top - heat gun, medium duty wire cutters (blue handle), large gauge wire crimper with multiple dies, 2/0 x 5/16 post lugs, heat shrink tubing,  2/0 wire.

Heavy duty wire cutter and a sharpie style marker are essential tools missing from the image above. 

I’m not certain if there is a technical difference between lugs and ring terminals.  In my vernacular ring terminals are used with smaller gauge wire and typically have heat shrink insulation already installed.  Lugs are typically non-insulated fittings for larger wire.  If anyone out there has a different definition / delineation, then please let me know.

22ga to 8ga insulated ring terminals on left.  6ga to 2/0ga lugs on right.

Ring terminals and lugs need to be sized to the correct gauge of wire and to the correct post diameter.  In the image below both lugs are for 2/0 wire.  The lug on the right fits a 3/8” post and the one on the left fits a ¼” post.

Two 2/0ga lugs with holes for different size posts.

Avoid aluminum when purchasing wire connectors.  Like marine wire all terminals and lugs should be tinned copper.

I’ve found my medium duty wire cutters will realistically work on wire up to around 1 gauge.  0 through 4/0 wire will require large cable cutters.  Sailing vessels should be carrying large cable cutters to deal with wire rigging in the event of a dismasting (See our C’est la Vie post: Dis-masted – Part 2 if you doubt the necessity of having large cable cutters aboard.)  Cutting 4/0 wire is easy with the large cable cutters. 

Once the wire is cut to the proper length, slide a section of heat shrink tubing for each lug to be installed onto the wire.  Sliding the heat shrink over the wire at this point will aid in avoiding any fraying of the wire once the insulation is removed.  Next, using the lug as a guide mark the amount of insulation to be stripped off the end of the wire.

The medium duty wire cutters are my tool of choice for stripping wiring larger than 10 gauge.

Stripping 2/0 wire using medium sized wire cutter.

Apply gentle pressure to the handles while rotating the cutters around the wire.  I prefer to rotate back and forth through 180 degrees.  Rotating through 360 degrees is ergonomically awkward and often results in a spiral cut on the insulation.  Stop the motion when you begin to feel the strands of copper against the edge of the cutters. Knowing when to stop cutting and how much pressure to apply comes with practice. 

Once the insulation is gone, I move directly to installing the lug.  Expediency at this step will aid in avoiding any fraying of the small stands of copper wire. 

Crimping a lug on a 2/0 battery cable.

Once the crimping is completed, I give the lug a through visual quality inspection.  If satisfied with the connection, then slide the heat shrink tubing over the junction and let the heat gun do the rest.

Numerous 2/0ga battery wires in Pilgrim's house battery bank.

Happy Crimping!

Let's Talk Marine Wire

Within days of Pilgrim arriving in Beaufort, Feb. 2014, we removed all of the existing wiring.

Creative and dangerous wiring in Pilgrim's bilge.

34 years of modifications and repairs to the electrical system by many hands left a hodgepodge of wiring.  Almost all of the wiring was sub-standard.  Some was outright dangerous - note unfused bilge pump wire run joined with wire nuts in image above – YIKES!

Unfortunately Morgan Yachts did not use marine grade wire in the original construction.

Factory installed shore power circuit breaker removed from Pilgrim.

So all the original wiring was also removed.

Gutting the original electrical panel.

All the wire going back into Pilgrim is marine grade.  So what makes marine grade wire different from home or automotive wiring?

• Marine grade wire is composed of tiny copper strands.  The wiring in a land based structure is typically a single thick copper wire. Stranded wire has more flex.  This allows the wire more easily fit into the tight spaces on a small vessel while placing less stress on connections.
• All the tiny strands of copper in a marine grade wire are tinned (plated with tin.)  The tin coating protects the copper from corrosion due to moisture and heat.
• The plastic insulation covering the exterior of marine grade wire is designed to resist degradation if exposed to fuel or oil.  This is very important for wiring in bilges and engine compartments.

What about the size of the wire (yes it does matter – haha.)  Size of electrical wiring here in the USA is designated by the American Wire Gauge (AWG). Wiring on marine vessels can vary from tiny 22 to 26 AWG in electronics and NMEA backbones to 00 (2/0) or 0000 (4/0) AWG wire in high amperage wiring for starter motors, windlasses, electric winches, etc.  Typically wires equal to or less than zero are referred to as “aught” (e.g. 2/0 is “two aught” and 4/0 is “four aught”).  

Wire must be properly sized based on type of current (AC or DC), voltage (12, 24, 120, 220), load current required (Amps), and total length of circuit (Feet).  If you are looking for more information, I recommend Blue Sea Systems: Choosing the Correct Wire Size for a DC Circuit.

The article above is the source for my preferred 12V DC Wire Sizing Table.

The sizing chart does not tell the entire story.  Each wire size also has a maximum ampacity. 

Ampacity is defined as the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration.

Thanks to Wikipedia for the speedy definition.  Factoring a wire’s ampacity and fusing wire runs accordingly is critical in primary wiring (i.e. feeds to battery selector switches, to electrical panels, to ground bus, etc.) and wiring for high amp components (i.e. starter motors, windlass, electric winches, etc.)  Here is a handy chart for maximum ampacity.

Choosing the correct size wire and fusing it below its rated ampacity is critical for the proper functioning of on-board systems and for the safety of all aboard.  I’ve printed both of the tables above and keep them handy in a plastic sheet protector when working on electrical systems.

Hope this information is helpful.  If anyone reading this post feels the information is stated incorrectly or it is misleading please let me know via a comment. 


I’m in full support of boat owners getting dirty and tackling their own projects, but if uncertain when assessing, altering, or installing electrical systems in your vessel please seek professional assistance.

Wiring Schematics for Pilgrim’s Primary 12V DC System

We have held back posting schematics for Pilgrim’s primary 12V DC system,

until now…

Why now?  Despite spending hours upon hours spread out over months drafting, researching, modifying, testing, modifying, modifying, modifying the schematic, the design continued to evolve throughout the installation.  

The heavy rains that flooded the Carolina's over the past couple weeks provided the perfect excuse for locking myself away inside Pilgrim and completing the primary 12V wiring install.   I plan to pen some additional posts about the install in the near future. 

Initially, I attempted to place both the positive and negative wiring on the same drawing, but the schematic became too noisy and confusing.  The schematics were completed using Google Draw.  If you would like to view the Google Draw files, with active hyperlinks,  use these links:

SV Pilgrim Primary 12V DC + Schematic

SV Pilgrim Primary 12V DC - Schematic

I welcome questions or comments on the designs.