The problem: Corroded terminals
Corroded battery terminals can cause
more problems than just poor starting.
The “blooming” corrosion taking place
on the battery terminals shown is a
pretty extreme example. But even
minor corrosion can reduce alternator
output by 30 percent. That can stress
your charging system and cause early
failures.
On the starting side of things, the
extra resistance causes slower cranking,
overheated starter motor windings
and premature starter failure (at about
$400 each, including labor!). Prevent
premature failures by replacing old corroded
terminals. You just need a set of
wrenches, a hacksaw and about an
hour. The best part is, the whole job
costs less than $20.
Step 1: Check the battery terminals and cables
1 of 1
Super corroded terminal
Unbolt the cable terminals and clean both the terminals and the battery posts
If the battery terminals have minor corrosion,
just remove them and clean
them and the battery posts with a wire
brush. Using the wire brush, neutralize
the battery acid with a baking soda/
water solution. Or buy a can of battery
terminal spray cleaner. Dry off the
battery with paper towels. Then apply
acid neutralizing felt pads (about $3 a set) to
the posts and connect the cleaned terminals
(Photo 4).
Finish the job by coating each terminal
with anti-corrosive spray. If the
old plastic guards are damaged, install
new ones (about $5 a set). But if either or both
terminals don’t clamp tight or the corrosion
is eating away at the metal, they
should be replaced. And if you see any
green corrosion on the copper cable
going into the molded lead terminals,
it’s a goner.
Step 2: Buy the best terminals
1 of 1
Photo 1: Don’t make this mistake
Cheap lead terminals can compromise
electrical connections. A copper compression
terminal offers the best connection
and costs only a few bucks more.
Every auto parts store sells cheap lead
battery terminals (see Photo 1). They
work. But the clamp plate squashes the
cable flat, so you only get partial electrical
contact. Instead, get pro-style
cast-copper compression terminals.
A compression terminal is made from
tinned copper and makes full
360-degree contact with the cable. Seal
the entire connection with heat-shrink
tubing to prevent corrosion. Buy
QuickCable brand battery terminals at
NAPA for $3 to $8 each, depending on
the cable size. Also buy red and black heat-shrink
tubing.
Step 3: Replace the battery terminals
1 of 3
Photo 2: Say goodbye to the old terminals
Cut the cable right where it exits the
terminal. Recycle the old lead terminals—they shouldn't go in the trash.
2 of 3
Photo 3: Install the new terminal
Hold the compression nut with a wrench and rotate the terminal
to compress the connection.
3 of 3
Photo 4: Put it back together
Reassemble the connection, using neutralizing felt pads under
each terminal. Then tighten the terminal nuts and spray on a liberal
coating of anti-corrosive spray.
Disconnect both battery terminals. With the battery terminals disconnected,
use a slip-joint pliers to hold the
terminal while you hacksaw it from the
cable (Photo 2). Don’t saw it off while it’s
still on the battery. Next, cut off about
1/2 in. of insulation from each cable. If
the copper strands are green, clean
them with a baking soda/water solution
and a wire brush. Dry the cable with
compressed air.
Slip the heat-shrink tubing over the
cable and slide it down so it’s out of the
way. Then insert the main cable and
any smaller cables into the compression
nut. Screw on the battery terminal
and tighten until snug (Photo 3). Then
slide the heat-shrink tubing over the
connection and use a heat gun to
shrink it.
Always wear eye protection when
working on car batteries, and don’t
smoke.
