Batteries
Car Batteries
 A
car battery is principally used to start the engine. It is also used to
filter or stabilize power and to provide extra power for the ignition,
lighting and other accessories when their combined load exceeds the
capability of the charging system, i.e., when the engine is idling. It
also provides power to the electrical system when the charging system is
not operating. The battery lies hidden under the bonnet and is an
essential component of your vehicle. Regular care is a must, for if it
in bad shape, the car will refuse to move. "Push-start" is a
solution but cannot be carried on for long. A well-maintained battery
lasts for two years. Regular care of your battery is a must, otherwise
your car will not move. "Push-start" is an option but not a
long term solution. A well maintained battery usually lasts for two
years.
Points to note when buying a new battery
Climatic conditions determine the kind of battery you should buy.
Colder climates require batteries with higher CCA ratings than in a hot
climate.
Cold Cranking Amps (CCA)
The most important consideration is sizing the battery's CCA rating to
meet or exceed, depending on the climate, is the car's OEM cranking
requirements. CCA's are defined as the discharge loads measured in amps
that a fully charged battery at 0 degrees F (-17.8 degrees C) can
deliver for 30 seconds while maintaining the voltage above 7.2 volts.
Batteries are sometimes advertised by their Cranking Performance Amps
(CA) or Marine Cranking Amps (MCA), which is measured at 32 degrees F (0
degrees C) or Hot Cranking Amps.
HCA is measured at 80 degrees F (26.7 degrees C), which is not the same
as CCA. Do not be misled by CA, MCA or HCA ratings. Multiply the CAs by
8 to convert Cas to CCAs. To convert HCAs to CCAs, multiply HCAs by
0.69.
Buying batteries with double or triple CCA ratings that exceed the OEM
requirement are a waste of money for hot climates. However, in colder
climates the higher the CCA rating the better, due to increased power
required to crank a sluggish engine and the inefficiency of the cold
battery. As batteries age, they are less capable of producing CCAs.
One of the major battery manufacturers, Exide, publishes the following
table:
| Available Power
from battery |
Temperature
Degrees F |
Power Required to
crank engine |
| 100% |
80 |
100% |
| 65% |
32 |
155% |
| 40% |
0 |
210% |
| 25% |
-32 |
350% |
If more CCA capacity is
required, two (or more) 12 volt batteries can be connected in parallel.
Within a BCI group size, generally the battery with more CCA will have
more plates because a larger surface area is required to produce the
higher current.
Reserve Capacity (RC)
The Reserve Capacity rating is the second most important consideration
while buying a battery. This is because of the effects of an increased
parasitic (key off) load and in emergencies. Reserve Capacity is the
number of minutes a fully charged battery at 80 degrees F (26.7 degrees
C) can be discharged at 25 amps until the voltage falls below 10.5
volts. More RC is better in every case! In a hot climate, for example,
if your car has a 360 OEM cranking amp requirement, then a 400 CCA rated
battery with 120 minute RC with more electrolyte would be more desirable
than one with 1000 CCA with 90 minutes of RC. If more RC is required,
two six-volt batteries can be connected in series or two (or more) 12
volt batteries can be connected in parallel. Within a BCI group size,
generally the battery with larger RC will weigh more because it contains
more lead.
Type
Low maintenance (non-sealed) and maintenance
free (non-sealed or sealed) are the two most common types of
car batteries.
The advantages of maintenance free batteries are less
preventative maintenance, longer life, faster recharging, greater
overcharge resistance, reduced terminal corrosion and longer shelf life,
but they are more prone to deep discharge (dead battery) failures due to
increased shedding of active plate material.
In hot climates, buying non-sealed batteries is recommended
because a sealed battery will not allow you to add water when required,
or to test the specific gravity with an external hydrometer. Some
manufacturers introduced a third type of car battery, "dual",
that combined a standard battery with switchable emergency backup cells.
For about the same cost a better approach was to buy two
batteries and isolate them.
It is best to buy a commercial or AMG battery for excessive vibration
applications. Car batteries are specially designed for high initial
cranking amps (usually for five to 15 seconds) to start an engine;
whereas, deep cycle (or marine) batteries are designed for prolonged
discharges at lower amperage.
A "dual marine" battery is a compromise
between a car and deep cycle battery; However, a car battery will give
you the best performance in a car. For RVs, a car battery is used to
start the engine and a deep cycle battery is used to power the
accessories. The batteries are connected to a diode isolator and both
are automatically recharged by the RV's charging system when engine is
running.
Size
Batteries are generally sold by model, so the group numbers will vary
for the same price. This means that for the SAME price you can
potentially buy a physically larger battery with more RC than the
battery you are replacing, e.g. a 34/78 group might replace a smaller
26/70 group and give you an additional 30 minutes of RC.
If you do this, be sure that the replacement battery will fit, the
cables will connect to the correct terminals, and that the terminals
will NOT touch the hood when closed.
BCI and the battery manufacturers publish application guides that will
contain the OEM cranking amperage requirements and group number
replacement recommendations by make, model and year of car, and battery
size, CCA and RC specifications. Manufacturers might not build or the
store might not carry all the BCI group numbers. To reduce inventory
costs, dual terminal "universal" batteries that will replace
several group sizes are becoming more popular and fit 75% or more of
cars on the road today.
Freshness
Determining the "freshness" of a battery is sometimes
difficult. A battery that is more than six months old should never be
bought because it begins to sulfate. Sulfation occurs when lead sulfate
can not be converted back to charged material and is created when
discharged batteries stand for a long time or from excessive water loss.
Warranty
As with every thing else, it is necessary that you check the warranty
period of the battery before you buy it.
It is extremely important to note that
batteries contain a sulfuric acid electrolyte, which is a highly
corrosive poison. It produces gasses when recharged and explode if
ignited. When working with batteries, you need to have plenty of
ventilation, remove jewelry, wear protective clothing and eyewear
(safety glasses), and exercise caution. Whenever possible, you are
requested to follow the manufacturer's instructions for testing,
jumping, installing and charging. |
