A battery must provide emergency power for ignition, lights, etc in the event of failure in the vehicles battery recharging system.

The Battery Council International (BCI) defines Reserve Capacity as "the number of minutes a new, fully charged battery at 80 degrees Fahrenheit (26.7 degrees Celcius) can be discharged at 25 amperes and maintain a voltage of 1.75 volts per cell (10.5 volts for a 12 volt battery) or higher."

The primary function of the battery is to provide power to crank the engine during starting at under low temperature condition. The Battery Council International defines CCA as "the discharge load in amperes which a new, fully charged battery at 0 degrees Fahrenheit (-17.8 degrees Celcius) can deliver for 30 seconds and maintain a voltage of 1.2 volt per cell (7.2 volts for a 12-volts battery) or higher".

CA or Cranking Amps is the discharge load in amperes that a new, fully battery at 32 degrees Fahrenheit (0 degrees Celsius) can continuously deliver for 30 seconds while maintaining a terminal voltage equal to or higher than 1.20 volts per cell. The CA rating of a battery may be 10 % to 30 % higher than its CCA rating. The Battery Council International (BCI) does require that, when a battery carries a statement of its CA performance, it must also carry a statement, in equal prominence, of its CCA capacity .

Normally, It need periodically check the battery. Clean the terminals and the cables if they look dirty or corroded. The top of the battery should also be kept clean of heavy dirt and oil accumulation to prevent low - grade short circuiting .

Some batteries are equipped with removable pods or vents so that the electrolyte level in each cell can be checked and filled with water if the level is low. Always use good quality distilled water to prevent iron or other chemical contamination which could drastically reduce the battery's life and power. Be careful not to overfill (past the end of the fill well barrels) or acid may be pumped or expelled during operation or charging .

If your vehicle has set unused for an extended period of time (a month or more), you should recharge the battery before using .

Ten years ago, original equipment batteries are bigger in external size than now. It mean battery technology has advanced significantly over the year, so their ratings are higher .

The new consolidated lines simply take advantage of current technology by substituting these newer, more compact group sizes for older and physically larger "regular" battery group sizes .

Given current technology there is, of course, an upper limit to the amount of power any given external geometry can deliver

• Supply power to the starter and ignition system.
• Supply the extra power required when the vehicle's electrical load requirement exceed the supply from the charging system.
• Act as a voltage stabilizer in the electrical system. You should not use a battery with rating lower than which the vehicle manufacturer recommends. In fact, going to a higher rating will improve starting ease for older vehicle and, in general, provide longer battery life .

Heat causes higher rates of self - discharge and accelerates positive - plate grid corrosion inside the battery. Reduce life of battery. Heat also increases evaporative water losses from the electrolyte. Battery capacity is greatly reduced at low temperature because the chemical reaction slows down significantly and electrolyte resistance increases. At 0 degrees Fahrenheit (-17 degrees Celcius), a battery will only deliver about 40 % of the power it would at 80 degrees Fahrenheit (26.7 degrees Celcius).

There are no Significant long - term effect, however, electrolyte can freeze if the battery is in a discharged state and cause damage to the plates or crack the container. For example, electrolyte at 1.160 specific grafity (a battery which as about 55 % discharged) will freeze at 0 degrees Fahrenheit (-17.8 degrees Celcius). Batteries at usable states of charge will not freeze at temperature above -20 degrees Fahrenheit (-28.9 degrees Celcius).

Each is important and they are interrelated. To understand this better, we must look at what happens when a vehicle is started. in order for starting current to flow, the battery voltage (the pressure which causes the current to flow) must be at or above a minimum level, and the electrical circuit must be complete (ignition switch on). As current is withdrawn, the battery's voltage decays slowly at first (after the initial instantaneous drop) and the more rapidly as the discharge continuous. Normally the engine fires and runs within a couple of seconds without sustained or repeated cranks .

The load (work) required to crank the engine determines how much current the starter will draw. It draws only what it needs regardless of the excess CCA capacity the battery may have.

If the engine doesn't fire and run and if cranking is sustained, the current discharge continuous until there is insufficient pressure (voltage) to supply the required current, and cranking slows to a stop.

CCA is usually stressed in comparing battery performance, and a higher rated battery will typically give longer cranking time under the same load conditions.

CCA, however is only a very specific characteristic geared to a worst - case starting condition 0 degrees Fahrenheit or -17.8 degrees Celcius). This is not a typical condition.

A battery can be made to meet its CCA rating but fade rapidly at the end of the 30 second test limit. It is also possible to make a battery which meets its CCA rating, but sustains voltage better at more typical starting current and temperatures and has much better Reserve Capacity.

Depending on your driving habits and region, it may be better to select a battery with comparatively high reserve capacity (at the required CCA) rather than simply looking at batteries with higher and higher CCA ratings.

Before attempting to charge a battery, be aware of all the safety precautions you should observe during the charging operation. Always unplug or turn the charger off before attaching, "rocking" or removing the clamp connections. Carefully attach the clamps to the battery in proper polarity (usually red to positive + and black to negative -). Keep open flames and sparks away from the battery, the gases coming from it are highly explosive. Ventilate the battery well during charging. Follow the battery charger manufacturer's instructions.

When possible, use chargers with alternator or polarity protection that prevents charging a battery in reserve. The charge a battery receives is equal to the charge rate in amperes multiplied by the time in hours. Thus a five ampere rate applied to a battery for ten hours would be a 50 ampere - hour (AH) charge to the battery. To fully recharge a battery, you must replace the ampere - hours or ampere minutes removed from it, plus an extra 20 % charge. This is due to the fact that batteries are not 100 % efficient on recharging.

Specific charging rates or times cannot be specified for batteries due to following :

1. The electrical capacity of the battery, the charge required to recharge a fully discharged battery depends on the battery capacity rating. An 80 minute reserve capacity battery requires twice as much recharging as a 40 minutes reserve battery .
2. Temperature of the electrolyte - a partially charged battery will accept the maximum permissible charge rate at 80 Fahrenheit (26.7 Celcius) but will accept only a fraction of this rate at 0 Fahrenheit (-17.8 Celcius). Reference safety Precaution for charging batteries below 32 Fahrenheit (0 Celcius).
3. Battery state of charge at the start, of the charging period - a completely discharged battery requires twice as much charge as a one - half charged battery.
4. Battery age and condition - a battery that has been subjected to severe service will require more charging than a relatively new battery, but the temperature will rise faster. As the temperature rises, the battery charge acceptance increases. Guard against overheating .
5. Caution : do not attempt to charge a frozen battery. Allow the battery to warm to 60 Fahrenheit (15.5 Celcius) before placing on charge .

Batteries should always be treated with caution, whether undercharged or not. All lead - acid batteries contain highly corrosive sulfuric acid and generate explosive gases. Read and follow all warning labels displayed on the battery .

Even so - called "sealed" maintenance - free batteries have small vents to relieve the pressure of internally generated gases and can leak or spew acid if tipped or charged too vigorously .

Although hydrogen and oxygen are always being generated, they are produced in great quantity when the battery is being charged, therefore, several precautions should always be taken :

1. Always charge a battery in an area where the charger and battery are well ventilated and unlikely to be disturbed .
2. Never allow smoking, open flames, or sparks near a battery - undercharged or not .
3. Always switch off and unplug the charger before connecting or disconnecting the battery. Make sure the leads are connected to the proper battery terminals .
4. Never wiggle the connections to check contact while the charger is on or plugged in .
5. Do not allow the battery to overheat (become hot to touch) during recharge
6. Keep the vent pods or plugs in place recharging .
7. Read and understand the charger manufacturer's instruction before attempting to use the equipment .

The charging current and time required depends upon the charger being used and the battery in question. Most chargers automatically adjust to the battery's state of charge and shut off when the battery becomes adequately charged. Many chargers have minimum voltages that must be present in the battery before the charger will switch on. Normally, voltages that must be present in the battery before the charger will switch on. Normally ,these low voltages are well below those exhibited by a battery that appears "dead" to a vehicle's electrical system .

Some chargers have optional settings for six versus twelve volts and / or low maintenance versus standard or deep-cycle batteries. Be sure you have made the proper setting.

If the charger requires manual adjustment for current or shut-off, check the charger's instruction for the settings appropriate to the battery's rating .

Warning that a battery may need replacing or that the electrical system needs checking include :

1. Slow or interrupted turn over of the starter motor .
2. The instrument panel indicates battery "discharge for extended periods after the engine is running.
3. The battery seems to lose power quickly in cold or extended starts .
4. The headlights dim at idle.

Unfortunately, many times there is little if any warning. If you suspect your battery is failing, the prudent thing to do is to have it load tested or replaced.

Step 1. Visual Inspection

1. Visually inspect the outside of the battery for obvious damage such as a cracked or broken case or cover which would allow electrolyte loss. Check for terminal damage. If obvious physical damage is found, replace the battery. If possible, determine the cause of damage and correct.

2. Check the condition and size of the cables. Are the cable clamps tight? Check for corrosion on the terminal or clamps. Clean corroded parts and / or tighten clamps if necessary. Replace badly corroded cables or cables with defective terminals. Make certain the negative cable is making a good connection where it is grounded to the engine and the positive cable to the starter relay. If the battery is satisfactory on the "Visual Inspection".

Step 2. Electrolyte Level And State of Charge

Check the electrolyte level in the cells if possible. The level can be seen though translucent plastic cases. It can also be checked in batteries which are not sealed. If the electrolyte level is below the tops of the plates in any cell, add water if the vents are removable. If the battery is sealed, and water cannot be added to it, replace battery and check the charging system for a malfunction such as a high voltage regulator setting. Follow instructions of manufacturer if the battery has a special indicating device.

If the level is OK, unknown or water can be added to the battery, and the stabilized open circuit voltage is below 12.4 volts, charge the battery as described under charging. The voltage is stabilized if battery has stood over night without being charged or discharged. If the battery has been on charge, the voltage can be stabilized by placing a 15 ampere load across the terminal for 15 seconds.

Is the battery is in the car, another method of stabilization is to turn on the "bright" headlamps for 15 seconds .
Read the voltage at least three minute after the discharged load is removed. When the hydrometer reading can be taken, a value of 1.225 @ 80 Fahrenheit (26.7 Celcius) can be used instead follow the instructions of the manufacturer. After the battery is recharged, stabilize the instructions of the manufacturer. After the battery is recharged, stabilize the voltage as described above, then proceed to step 3 .

Step 3. Load Test Procedure

The load test procedure is conducted to determine if the battery requires recharging or replacement .

1. Disconnect the battery cables (ground connection) and connect the voltmeter and load test leads to the battery terminals, making sure the load switch on the tester is in the "off" position.

2. Apply a test load equal to 1/2 Cold Cranking amperes @ 0 Fahrenheit (-18 Celcius). Rating of the battery for 15 seconds. (Example : a battery has Cold Cranking Rating @ 0 Fahrenheit (-18 Celcius) of 350 amperes. Use a test load of 175 amperes).

3. Read the voltage at 15 seconds and remove the load. If the voltage is less than the minimum specified, replace the battery. If the voltage meets or exceeds the specified minimum, clean the battery and return it to service.

If the state of charge of a battery cannot be determined and the battery fails the load test, it must be recharged and retested. If it meets the specified voltage on the second test return it to service. If it does not meet the specified voltage on second test, replace the battery.

The above is a standard test procedure to determine the ability of a battery to function properly. If a commercially available tester is being used to analyze the battery, follow the instructions of the equipment manufacturer.

The actual frequency will depend the climate, region and road condition also the driver. If you're disappointed with the battery life you get and your car's electrical system is in good operating condition, you should upgrade.

Diesel (compression ignition / fuel injected) engines do require significantly more starting energy (time and power).

Some four - cylinder engines do require more power than six - cylinder engines. The starter normally turn at a higher r.p.m. and you have fewer chances to "fire" per revolution. However, many other factors come into play such as compression ratios, starter motor design, vehicle option, etc. Always consult the owner's manual or battery application guide for the minimum rating for the application in question .

Before removing the old battery, carefully note the location of the positive battery terminal and mark the polarity on the positive cables. In this way you can avoid installing the new battery reversed. Remove the "ground" terminal first. This precaution is to avoid damage to wiring and the battery by accidental "ground" with tool.

In removing or tightening the hex nut on the bolt of clamp terminals use the proper size end wrench. Use an end wrench to remove cables from side terminals, stud terminal or "L" terminals.

Inspect the cradle for possible damage caused by loss of acid from the old battery. Be sure the cradle and its hold downs are mechanically strong and free from corrosion. Corroded parts and cable terminals may be cleaned with water, to which some household ammonia or baking soda has been added, by scrubbing with a stiff brush. Corroded steel parts should be dried and painted with acid - proof paint. Do not paint battery terminals. Clean and tighten the "Ground" connection. Tighten starter relay and connections.

In general, longer warranty periods are assigned to higher capacity batteries that is, batteries with more or longer plates and hence higher CCA and reserve ratings. You can not, however, relate the warranty period to actual service life, except in comparative term, i.e., batteries with longer warranties will, on average, live longer than those with shorter warranty periods, given the same conditions (vehicle application, driving pattern, climatic region, vehicle conditions, etc).

For example, the life of a 500 CCA battery in 300 CCA application will be better than the life of the same 500 CCA battery (with the same warranty) in a 500 CCA application