Batteries - How Do You Know You'll Have the Juice When You Need

By: Brendon Turner

Modern vehicles make a lot of demands upon their batteries. We
expect our batteries to be reliable, have a large reserve
capacity and a long life span, and be maintenance-free. In
short, once a battery has been installed, we no longer want to
think about it. Here's some tips on how to choose a battery that
will serve you well.

For automotive applications, there are basically three types of
batteries: conventional, maintenance-free, and recombination.

Conventional Batteries

A 12-volt automotive battery contains six cells. In each cell is
a series of alternating positive and negative plates, between
which are isolator or separator plates to keep them apart. All
the negative plates in the battery are connected, as are all the
positive plates. Each plate has a grid construction, and to this
grid, the plate's active material - sponge lead - is bonded. The
plates in each. cell are covered with a solution of distilled
water and sulfuric acid (electrolyte). As the battery discharges
(supplies electricity), the acid in the electrolyte reacts with
the active material in the battery plates, forming lead sulfate
and weakening the electrolyte solution. Conversely, as the
battery is charged, the acid is returned to the solution,
thereby strengthening it, and the used portion of the lead
sulfate is converted back into active material in the plates.
During this process, hydrogen and oxygen molecules are
off-gassed out of the electrolyte, which is why a conventional
battery often needs topping up with distilled water. The charge
and discharge cycle also means that some lead sloughs off the
plates. Over time, this builds up in the bottom of the case,
reducing the overall capacity of the battery fluid. When enough
material builds up, the plates will short out, and you're stuck
with a dead battery.

Maintenance-Free Batteries

Closed (maintenance-free) batteries are essentially the same as
conventional batteries, except that they contain extra
electrolytes in the partially sealed case. However, over time,
this excess fluid is used up as fluid slowly off-gases hydrogen
and oxygen molecules through the vents. Because these batteries
cannot usually be topped off, once the plates begin to be
exposed, the battery's life span is over. Usually, this takes a
long period of time, which is why these batteries often last
longer than conventional batteries. However, in situations where
frequent, rapid charge/discharge occurs (such as when running a
winch or powerful spotlight without running the engine), a
maintenance-free battery may not outlast a conventional one.

Another type of maintenance-free battery is the gel-type battery
While these batteries cannot leak or spill fluid and can be
installed at odd angles, they do have a weakness. Using
electrolyte gel necessitates the use of thinner plates so that
adequate dispersion of the acid through the active material
occurs. Since gel batteries are also sealed, they cannot be
topped off and care must be taken when charging so they don't
overcharge and gas-off, which will result in excessive sloughing
of the plates, premature reduction in electrolytes, and eventual
battery failure. This means that during the harsh vibrations
associated with trail riding, a marginal gel battery can fail
completely as the plates literally fall apart.

Recombination Batteries

The recombination battery is overall the best battery for
off-road and heavy-duty use. They're called recombination
because they recombine the gas formed during charging,
channeling it into the separators so it doesn't vent out of the
battery and reclaiming the water to keep electrolyte
concentration at optimum. They are completely sealed (except for
a reseating pressure-relief vent) and require no topping off of
fluids. Recombination batteries can use either liquid or
gel-type electrolytes and are different from other batteries
because the acid is bound into the separators and pure lead can
be used in the plates. Because of the purity of the materials
used, there is no sloughing and the plates in these batteries
can be very tightly packed. The result is a powerful, compact
battery with quicker charging time, lower internal resistance
than conventional or maintenance-free batteries, and a longer
life span. In fact, for a conventional battery to deliver the
same amount of starting power as a recombination battery, it
would have to be two or three times larger. Because they contain
no liquid as such, recombination batteries can be mounted in any
position, will work when the case is damaged, and won't leak in
a rollover. In short, for off-road use, they are just about the
perfect battery.

How Batteries Are Rated

Battery ratings are a determination of how much power a battery
can produce under marginal conditions. There are a number of
ways to determine a battery's output, but ratings by ampere hour
(Ah), cold-cranking amperes (CCA), and reserve capacity are the
most common.

Ampere hours are determined by the SAE 20 test. This test is
designed to show the amount of current that can be drawn from a
battery for 20 hours without the voltage dropping below 1.75
volts per cell. In real-world terms, this means that a healthy
battery should be capable of keeping the parking lights lit for
20 hours. For starting your truck, Ah doesn't mean much.
However, for powering accessories without the engine running,
this can be an important measurement.

Cold-cranking amperes or CCA is the unit of measurement that
generally determines a battery's ability to start your engine.
CCA is a measurement of the worst conditions under which a
battery can be expected to deliver current, and it tests how
much current in amperes a battery can deliver under extreme
cold. According to the American SAE standard, CCA is determined
by measuring how much current can be delivered in amperes for 30
seconds at -18 degrees C with a final voltage of 7.2 volts per
cell or higher.

Reserve capacity is an important measurement for the total
capacity of the battery and shows how long a battery can keep
the engine running if the alternator/generator fails. Reserve
capacity of a battery is measured in minutes at room temperature
(approximately 70 degrees F). During this test, 25 amperes is
drawn from the battery for as long as the voltage does not drop
below 10.5 volts. For off-road use, it's a good idea to make
sure any battery you purchase has a reserve capacity of at least
120 minutes.

Reserve capacity is also important for those times when you need
to run a radio, spotlight, winch, or other electrical accessory
without running the engine.

A Batteries Two Enemies

Although just about all modem batteries are pretty reliable,
there are two enemies that can grind even a brand-new battery to
a halt - extreme cold and extreme heat. Batteries are at their
best with internal temperatures (not ambient) above 50 degrees F
and below 105 degrees F. Below and above this range, problems
can develop, and a dead, damaged, or . useless battery can be
the result.

We've all noticed that under extremely cold conditions (below
freezing), the battery will turn over the starter motor slowly,
if at all. This is because when the internal temperature of the
battery gets below the optimum range, the chemical reaction
inside the battery happens more slowly, and for every 10-degree
drop below freezing, the time that the chemical reaction takes
doubles. Because of this increased resistance, the voltage in
the battery drops and cannot turn over the engine.

Heat can also have an adverse effect on your battery's overall
health. Battery power is reduced when it's subjected to
excessive temperatures, but the problem may not be immediately
noticed until the temperature drops. At higher temperatures, the
chemical reaction within the battery is more rapid. The battery
can produce more energy more quickly. This is good, right?
Wrong. The higher rate of energy production results in an
increase in off gassing; the water in the battery is vented out
as hydrogen and oxygen molecules and the rate of internal
corrosion, or sloughing, increases. This can result in a short
in one or more cells that is not noticed until cold weather
diminishes the overall ability of the battery.

What to Buy

When it comes to batteries for automotive use, there is no such
thing as a perfect battery. Any battery can fail if it is
neglected, constantly overloaded, or overcharged. The important
thing to remember is to get the right battery for your needs,
one that is rated for your vehicle and all the accessories you
use. Generally, this means a high Ah, high CCA, and high reserve
capacity. Also, make sure you buy a quality unit. Don't be
fooled by the low price of the budget shops. Batteries sold in
the no-name-battery discount stores often are poorly assembled
and use inferior materials in the plates and separators.
Name-brand batteries, such as AC-Delco, Sears DieHard, Exide,
Interstate, Optima, and others, are manufactured to the highest
standards, delivering high reliability combined with long life.

For off-road use, however, we feel that the recombination
battery is the best overall, since it delivers high output,
needs no maintenance, holds up well to the rigors of off-road
driving, and has a quick recharge rate, as well as a long life
span. It is a particularly useful battery for the off-roader
because it has no liquid to leak out and can be mounted in any
position (even upside down). Because of this, it won't corrode
battery trays or cables and is safe in a collision. You can
actually shoot a 45-caliber bullet through the battery casing
and it will still crank at full power. Try that with a
conventional battery, and you have a leaking mess that will at
best produce minimal voltage.

Although recombination batteries are sold under various brand
names, Optima's 800U is the original and also the only battery
available with both top posts and side terminals, a feature that
makes it especially well suited for specialized installations
and powering accessories and where there is installation room
for only one battery Since we also run a winch and driving
lights from the starting battery, it has to be a powerful one.
The 800 CCA and 120 minutes of reserve capacity the Optima
offers means we can rely on the unit as a power source for
lights and winch use when the engine is down, without
sacrificing starting ability. Additionally, the side terminals
make it easy to power the winch and other accessories directly
off the battery without disconnecting the main power cables and
disabling the vehicle's computer. This makes for a clean
installation without a lot of cable clutter at the main battery
posts, which is especially important when there's limited space
around the battery top.

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