Re terminal connection methods

[LEE A HART <XURQ03A@PRODIGY.COM>]

Lots of good comments on methods of termination. I've used all types
(including some no one has mentioned yet), and any of them can give good
results if done properly. The key word is "properly".

Every one's skills and needs are different, so there is no one best method.
You won't get it right the first time; it takes practice. You have to try
several, and master at least one of them. Study the pros and cons, pick one,
test your results, and practice until you master it.

Crimp

If you have the right tool and terminal for the wire size, and the parts are
clean, a high pressure crimp is the most reliable connection, and takes the
least skill. Just put the wire in the terminal, close the handles, and you are
done. The pressure is so high that the wire and terminal cold flow together,
making a joint that is essentially welded. There is no air space between the
parts, so no "goo" is needed (but it won't hurt). For the beginner who wants
fast results and isn't going to test his work, this is the way to go.

Hammer crimp

This is an el-cheapo crimper, to avoid the cost of a $200 tool. Under ideal
conditions, it can form a joint as good as a $200 tool. But this requires
skill, which means making lots of joints and testing the results (pull test
and temperature rise and voltage drop at high current). Contact lubricants may
help because the crimp will be inconsistent and there will be air spaces where
corrosion can occur. If you are on a tight budget and relatively unskilled,
use this method. But *test* each connection!

Soldering

This produces the lowest resistance and highest corrosion resistance
connections, but requires the highest skill level. Typical problems are not
enough solder (use a solder pot), not enough heat (cold solder joints), too
much heat (melted insulation or solder wicking into the wire), parts not clean
(solder won't wet them), and leftover flux (weak fluxes don't work with
oxidized parts, and active fluxes corrode wire unless removed).

If you solder, you have to crimp it first. Otherwise, the solder can melt and
drip out of an overheated connection, leaving a really dangerous hot connection.

If you are very good at soldering, and will test the connections, this is a
good way to go.

Casting

A lead terminal can be cast onto the wire. This is what you commonly see in
commercial terminals. Lead is a lousy, heavy conductor, but is obviously very
corrosion resistant. Overall connection resistance is slightly higher. Lead
has a tendency to cold flow so terminal can loosen over time.

This method is only practical if you are going to make a lot of terminals.
You'll have to make a mold and get a little setup for casting lead.

Welding

The wire can be simply welded to the battery terminal. Experts can wrap the
wire or flat strip stock around the terminal, and weld it with a quick pass of
a torch. I can't do it, and it seems very risky (you ruin a battery if you
botch the job). but I've seen it done and it can produce very good connections.

If you are an artist with a welding torch, you might try this (hopefully after
practicing on old batteries).

Screw terminals

You can buy lugs that secure onto the ends of a wire with screws. They range
from real garbage (the cast lead ones that pinch a wire between the terminal
and a flat plate with two screws), to high quality machined brass, copper, or
aluminum parts with specially designed setscrews. Good ones will pass the pull
tests and have low heating and voltage drops. Brass is as bad as lead for
conductivity, but copper and aluminum are good. Use "goo" in these connectors,
as you certainly don't get an airtight seal. This is about the only practical
method (short of welding) for aluminum wire.

This is a pretty good method for people with very low skill levels, but
expensive. The cost of terminals adds up fast (especially if you use gold
plated ones like John Wayland :-)

Bus bars

Instead of wire and terminals, you can use flat strips of metal and bolt them
directly to the terminals. Always put an "S" bend in them so slight motions
between batteries do not put huge stresses on the battery terminals. They will
soon leak if you do.

This is also a pretty good method for someone skilled at metal fabrication.
Corrosion resistance can be added via heat shrink, powder coating, etc.

Personally

After 20+ years of experimenting, I now use a $200 crimper, and then dip the
terminal in a solder pot. I don't use "goo" except on aluminum.

Lee Hart                     If you would not be forgotten
4209 France Ave. N.          Soon as you are dead and rotten
Robbinsdale, MN 55422 USA    Either write things worth the reading
phone (612) 533-3226         Or do things worthy of the writing
e-mail XURQ03A@prodigy.com   (Ben Franklin, Poor Richard's Almanac)
Re terminal connection methods