to tell if your battery is good or bad, turn it on and if nothing happens and
everything is dead then you have a dead battery, most likely. and sometimes it
can just be a loose cable.
Ray Boyce <[EMAIL PROTECTED]> wrote: The
condition of the cell plates inside the battery determines whether or
not a battery is still serviceable. Current is produced when sulfuric acid
in
the battery reacts with lead in the cell plates. As the battery discharges,
sulfate accumulates on the plates and reduces the battery's ability to make
current. The sulfate is returned to solution when the alternator recharges
the battery by forcing current to flow in the opposite direction.
Over time, some of the sulfate becomes permanently attached to the plates.
The sulfate forms a barrier that diminishes the battery's ability to produce
and store electricity. This process can be accelerated if the battery is run
down frequently or is allowed to remain in a discharged state for more than
a few days. If the plates have become sulfated, therefore, the battery won't
accept a charge and will have to be replaced.
Average battery life is only about four to five years under the best of
circumstances -- and sometimes as short as two to three years in extremely
hot climates
such as Arizona and New Mexico. But the battery may become "sulfated"
prematurely if it is chronically undercharged (charging problems or frequent
short-trip
driving), or if the water level inside the battery drops below the top of
the cell plates as a result of hot weather or overcharging and allows the
cell
plates to dry out.
Battery Testing
This is something you can't really do yourself, so you need to take your
vehicle to a service facility that has the proper test equipment. The
battery's
condition can be determined one of two ways: with a carbon pile "load test"
(that applies a calibrated load to the battery) or electronically with a
special
tester that measures the battery's internal resistance.
Equipment that uses a carbon pile for load testing requires the battery to
be at least 75% charged. If the battery is less than 75% charged, a good
battery
may fail the test. So the state of charge must be checked first, and the
battery recharged if it is low prior to testing. NOTE: The battery does NOT
have
to be fully charged prior to testing if an electronic tester that measures
internal resistance is being used.
If load testing with a carbon pile, apply a load that is equal to half the
battery's cold cranking amps (CCA) rating. A good battery should be able to
supply
half its CCA rating for fifteen seconds without dropping below 9.5 volts.
Does a replacement battery have to be the same size as my old one?
No. If your old battery has reached the end of the road and needs to be
replaced, or if you think you need a battery with a bigger amp capacity for
easier
cold weather starting or to handle added electrical accessories (such as a
killer stereo system, driving lights, etc.), then there's no reason why you
have to install a battery that's the same size as your old one.
The word "size" may be a bit confusing here because what we're really
talking about is the battery's amp or power rating, not the physical
dimensions of
its case.
A battery with a bigger case is not necessarily a more powerful battery.
Battery manufacturers can cram a lot of amps into a relatively small box by
varying
the design of the cell plates and grids. So two batteries with identical
exterior dimensions may have significantly different power ratings.
Batteries come in many different sizes and configurations (which are
referred to as "group" sizes) because the vehicle manufacturers can't get
together
and standardize anything. So when you're choosing a battery, you have to
consider three things: (1) the group size (height, width, length and post
configuration),
(2) whether your battery has top or side posts, and (3) how many amps will
be needed for reliable cold starting and vehicle operation.
Group Sizes
Because there are 57 different group sizes, many aftermarket replacement
battery suppliers consolidate group sizes to simplify inventory
requirements. So
some replacement batteries may not fit exactly the same as the original. The
battery may be slightly shorter, taller, narrower or wider than the
original.
But as long as it fits the battery tray and there are no interference
problems (too tall a battery may cause the cables to make contact with the
hood causing
a dangerous and damaging electrical short!), it should work fine.
Some replacement batteries come with both side and top posts to further
consolidate applications. Some also have folding handles to make handling
and installation
easier.
Battery Ratings
Though many replacement batteries are marketed by the number of "months" of
warranty coverage provided (36, 48, 60, etc.), what's more important in
terms
of performance is the battery's power rating which is usually specified in
"Cold Cranking Amps" (CCA) rating. The CCA rating tells you how many amps
the
battery can deliver at 0 degree F. for 30 seconds and still maintain a
minimum voltage of 1.2v. per cell.
In the past, the rule of thumb was to always buy a battery with a rating of
at least one CCA per cubic inch of engine displacement. But twice that is
probably
a better recommendation for reliable cold weather starting.
At the very least, you should buy a replacement battery with the same or
better CCA rating as your old battery or one that meets the vehicle
manufacturer's
requirements. For most small four-cylinder engines, this would be a 450 CCA
or larger battery, for a six cylinder application, a 550 CCA or larger
battery,
and for a V8 a 650 CCA or larger battery. Bigger is usually better. Extra
battery capacity is recommended if your vehicle has a lot of electrical
accessories
such as air conditioning, power windows, seats, electric rear defogger, etc.
Battery Installation
Most batteries are "dry charged" at the factory, which means they're
activated as soon as acid is poured into the cells. Even so, the battery may
require
some charging to bring it all the way up to full charge.
Most experts recommend charging the battery before it is installed
regardless of whether it is dry charged or not. This will ensure the battery
is at full
charge and lessen the strain on your charging system.
When the battery is installed, it must be locked down and held securely by a
clamp, strap or bracket. This will not only keep the battery from sliding
around
on its tray (which might allow the positive cable to touch against something
and short out the battery or start a fire!), but will also help to minimize
vibration that can damage the battery.
The battery cables should also be inspected to make sure they're in good
condition, too. If the cables are badly corroded, don't fit the battery
posts or
terminals tightly, or have been "fixed" by installing temporary clamps on
the ends, the cables should be replaced. At the very least, you should clean
the cable clamps and battery posts with a post cleaner, sandpaper or a wire
brush to ensure good electrical contact. A light coating of grease,
petroleum
jelly and/or installing chemically treated felt washers under the cable
clamps will help prevent corrosion.
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