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