Connectors, Terminals and Battery Clamps

During recent mectings and gatherings we’ve been asking your —_—- won’t be great enough to crank the engine fast enough to start
opinion on ways to broaden the appeal for this newsletter. it.
Several folks have suggested that articles on various marine The best way to keep this “Murphy’s Law” scenario from
systems or boat maintenance may be beneficial. Hopefully, this happening is to keep the battery connections clean, tight, and
column will be a forum for sharing the vast range of practical protected from corrosion and dirt. After tightening the clamp
experience accumulated by our membership. It is also intended coat it with some of the products designed for protecting battery
to be the place where you, the reader, can submit technical connections. You can find them in any chandlery or auto parts
questions and either obtain answers or direction to appropriate store. Do not use greases or light oil-based corrosion preven-
reference material tive compounds. These products can penetrate the area between
As I mentioned in the first “Tech Tips” article, I hope to the clamp and battery post, and decrease the contact area. They
present six topics related to marine electrical systems. These can even cause a cascade effect, potentially leading to a fire or
are: electrical wiring, alternators and regulators, batteries, explosion. I witnessed a fire on a boat that was caused by
grounding and bonding, radios and antennas, and instrumenta- ignition of the grease used to “protect” the battery terminals.
tion (depth, speed, GPS, LORAN, etc.). In the last article we Continuous cranking of a stubborn diesel caused a poorly
talked a lot about marine electrical wiring, but because I got a connected clamp to overheat enough to melt the grease. The
little long winded, we never covered the various methods for grease burst into flame and ignited the hydrogen gas being
connecting the wires to anything. So in this “about a page” produced by the battery. It was not a pretty sight.
long article we’ll look at the connectors, terminals and battery On a far smaller scale, the type of terminals and connectors
clamps that let the electricity get where we want it to go. that you use on other wires on the boat and the method you use
There are all sorts of ways to connect wires together or to to install them can be the difference between a great system and
electrical devices. Most of us have seen really great examples one that causes you continual grief. In an ideal world, all wires
of the wrong way to make these connections. Funny thing is tun directly from the electrical source to the load device with no
that you always find them on other peoples boats. They range connections except for the necessary circuit breakers and fuses.
from the wires that are jammed between the battery post and —Ok, but how do you attach them! Personally, I like to use ring
battery clamps, to the mega-bundle of wire that’s twisted terminal lugs in combination with terminal strips where appro-
together and held by single (and usually loose) wire nut. priate.
Admittedly, this is an extreme example, but hopefully you get Ring lugs have the advantage of not falling off the screw they
the point. Doing things the wrong way sets you up for a are attached to if it loosens up for any reason. If the device or
“Murphy’s Law” calamity. terminal strip you are attaching them to is in an awkward
The last article pointed out the right way to lay out a wiring _ position they can be hard to attach, but the safety factor of not
system and chose the correct size circuit breakers, fuses and having electrically hot wires hanging loose greatly offsets this
wire. This time we’ll look at the right way to fasten things inconvenience.
together. If we have everything sized correctly, we can deliver All sorts of ring terminals, or lugs, are available. | like to use
the electrical current from the source to the load devices with _the type that crimp onto the wire with a crimping tool and have
very little voltage drop. However, we can only do this if we an insulating vinyl sleeve over the barrel that the wire slips
have everything connected with the appropriate size and type of into. On the better made lugs the insulation is tapered on the
wire terminals and connectors. inside so that the multi-strand wire slips right into the hole.
Usually the largest wire “terminals” used on a boat are the These provide a good mechanical and electrical connection
clamps at the ends of the starting battery cables. We don’t give between the wire and the lug if you choose the right size. No
them a whole lot of thought until something doesn’t work. matter what type connector you use make sure that you get the
That’s usually the starter motor. And according to Murphy, it size that matches the wire’s size. If you don’t, the crimping tool
usually happens just when you need it most. The clamps must will distort the barrel end of the connector. Although you may
be capable of conducting high current to the starter with a have succeeded in getting the lug mechanically fastened to the
minimum of voltage loss. The amount of contact area between wire, you more than likely don’t have the correct electrical
the surface of the clamp and surface of the battery post is criti- contact area between the lug and wire. Using the wrong size
cal to the voltage drop (loss) across the connection under high crimping tool or a pair of pliers to crimp the lug will create the
current conditions. If the surfaces are dirty or the clamp is same effect. Combine this poor connection with a little dirt and
loose, the contact area between the clamp and post is reduced. salt corrosion and you have a good source for future problems.
The lack of surface area causes a resistance to the flow of The insulating vinyl sleeves on the lugs are usually color
current. As the starter current increases, more and more coded to match the colored dots on the crimping tools and the
voltage is dropped across the bad connection. This represents a _ size of the wire for which they are designed. Red colored lugs
power loss since power is equal to current times voltage (P=IE). are made to go on 22 -18 gauge (AWG) wire. Blue coded lugs
Under high current conditions the power available at the starter (Continued to Page 9)

are for 16 – 14 gauge wire. Yellow coded lugs are designed for
12-10 gauge wire. Better quality crimping tools have the termi-
nal size labeled right next to the machined crimp face. In many
cases, they also have a colored dot corresponding to the color
code for the lug. These color codes also apply to the in-line
splice connectors and other types of terminals. You don’t have
to be a rocket scientist to do the job correctly.

In general, avoid using spade lugs or bullet terminals if you
can. I avoid them because they can be pulled apart too easily.
Of course, in some applications that’s what you want, but
inspect them routinely if you have to use them. This type of
connector uses the spring tension of the outer shell to hold the
inner part in place. In a marine environment. they secm to be
more prone to corrosion and rapid deterioration. A ring termi-
nator screwed to a terminal strip provides a better electrical and
mechanical connection that is relatively easy to clean.

To establish a good electrical connection I always use tinned
copper lugs and solder the wire to the lug after it’s been
crimped. This may seem like overkill (and in anything other
than a marine environment it would be) but afier several years,
corrosion between the wire and lug can become a problem
Careful soldering not only prevents this from happening but
also establishes a superb electrical connection between the lug
and wire. If you are careful, quick, and have the right heating
element on the soldering iron, you can melt the solder to the
wire and lug without melting the vinyl insulation. If you
haven’t had a good conversation with your soldering iron lately.
forget you read this paragraph and go buy a good crimping tool!
Properly crimped and insulated lugs will last a long time.

Speaking of insulation, you can get lugs and line splices that
come with heat shrinkable insulating sleeves. They form a
good moisture seal between the insulating sleeve and wire
insulation when heated with a heat gun or hair dryer. The seal
will keep the salt corrosion at bay as long as it is not disturbed.
You can also use products like “Liquid Lectra Tape” or other
brush-able insulating material to seal up the insulation. Again,
you don’t have to go to this extreme, but may want to consider it
if the terminals could be exposed to salt spray.

Another good idea, that should be part of your annual mainte-
nance, is to spray all of the electrical terminals, except the
batteries, with an anti-corrosive spray that is designed for
electrical connections. There are many, many products to
choose from. “Practical Sailor” ran an article not too long ago
on the subject of corrosion preventive products. I like to use
CRC and Boshield. both of which fared well in the “Practical
Sailor” comparison tests. As I pointed out earlier there are
many excellent references on the subject of marine electrical
systems. “The 12 Volt Bible”, “Boatowners Illustrated
Handbook of Wiring”, and other books are available from most
good chandlers and catalogs. Gordon West’s articles in “Sail
Magazine” are excellent references, and well worth reading.
“Practical Sailor” has a good article on electrical wire crimpers
on page 24 of the June ’98 issue.

Hopefully this “about a page” long article has stirred up some
questions. Certainly your electrical system should not be
viewed as a “monster”. With a little knowledge and occasional
tender loving care you can easily tame it and save yourself some
money in repair bills.