Battery Care and Maintenance Guide

A car battery helps the vehicle to start up and continue running. Keeping your car on a regular maintenance and testing schedule with your mechanic will ensure your battery works properly. Maintain car batteries by checking them and cleaning them regularly, and charging them when necessary.

Below you can find tips on how to take care and maintain your vehicle’s battery.

Regular Inspection and Maintenance

If you do proper testing and inspection of your car’s battery at least once per month, it will help you to extend its service life and provide optimum performance.

Here is a guide on how to examine the battery:

The battery’s state of charge. Most batteries have a State of Charge Indicator on top of the battery that shows you the battery condition. But a voltmeter will give you more accurate results of diagnosing voltage or if the vent caps are removable a hydrometer will help to determine the specific gravity (SG) of the electrolyte.

  1. Make sure that the top of the battery is clean and dry as a dirty battery can be discharged across the grime on top of the battery.

  2. Check the terminals, screws, clamps, and cables for damage, corrosion , and dirtiness.

  3. For protection, apply a thin layer of grease to posts and cable connections.

  4. Examine the battery case for signs of physical damage or warpage. Usually, they are a good sign of overheated or overcharged batteries.

  5. If you have a battery which needs to be maintained, check for the amount of electrolyte covering the battery plates. If it needs to be topped up, refill it but do not overfill as the fluid levels will rise when the battery is fully charged and may overflow. Top up with distilled or demineralized water and never fill with sulphuric acid.

  6. If you have a maintenance-free battery, check the State of Charge Indicator. It indicates the battery’s condition whether the battery needs to be charged or replaced. Even if the indicator warns you about the battery replacement, you still may start the vehicle. But don’t ignore this State of Charge Indicator warning light as the electrolyte levels may be below the plates which can lead to an internal explosion.

  7. If you use your battery for seasonal applications only and after store it for a long time, it is recommended to recharge the battery fully before storing. Always check the voltage of it. If it drops below 12.5V, recharge the battery. And it is also essential to check the battery thoroughly before reconnecting to electrical devices.

Battery Testing

Battery testing should be a part of periodic vehicle maintenance routine whether or not a starting problem has occurred. On time replacement of the battery can help you avoid many additional costs and issues with the engine.

Make sure that the battery is fully charged before testing it. Even if the battery is slightly discharged, it can give you a wrong reading.

There are several ways of testing the battery. Let’s look at them:


The state-of-charge of a lead acid battery can be determined by the specific gravity (SG) of the electrolyte (its density compared to a reference such as water). The SG can be measured directly with a hydrometer or indirectly by the stabilized voltage with a voltmeter. But, in this measurement, the temperature of the acid can affect the result.

Digital Battery Testers

One of the easiest, safest, and quickest options of diagnosing the condition of the battery are microprocessor controlled digital battery testers. This tester works by transmitting a small signal through the battery that uses measurements of conductance or resistance (impedance) to indicate battery condition.

Some of the models of the digital battery testers provide battery, starting, and charging tests. And you can print the results immediately right after testing to the customer.

Adjustable Load Testers

The most reliable option to determine the starting capacity of a battery is the adjustable load testers. This test applies a real load similar to when cranking the engine. This load, however, does create a spark risk if leads are connected to corroded or loose terminals.

The standard test is to load the battery to 50% of its CCA rating (Cold Cranking Amperes) for 15 seconds. If the voltage reads above 9.6 volts the battery is ok. For example, a battery that has a CCA rating of 600 should be tested at 300CCA for 15 seconds.

The standard interpretation of the result is that if at the end of the 15-second test, the loaded voltage reading is between 9.6V and 10.6V, then the battery is deemed to be good. If the result is under 9.6V, the battery is not good and may not crank the engine. It is always recommended to check the individual manufacturer’s specifications before testing.

Constant Rate Discharge Testers

This is the easiest way to check the capacity of a battery. The tester works by discharging the battery at a pre-set current (Amps) until it drops to a preset disconnect voltage. The disadvantage of this testing is time. For example, if you need to test a 100 Ah (Ampere Hour) battery at 5 Amps, it could take up to 20 hours to complete the test.

Battery Charging

Charging a lead acid battery is actually the process of replacing the energy. The amount of energy necessary for full recharge depends on the depth of discharge, rate of recharge, and temperature.

Safety First

Before charging the battery with an external battery charger, it is essential to be aware of the safety precautions when charging batteries and follow the instructions outlined by the charger manufacturer.

  1. Turn the charger off before attaching, rocking, or removing the terminal clamps.

  2. Keep open flames and sparks away from the battery.

  3. Keep vent caps in place.

  4. Charge in a well-ventilated area.

  5. Follow the battery charger manufacturer’s instructions to avoid overheating.

During the charging process, dangerous explosive gases can be generated which can ignite, for example by sparks, naked flames, and static electricity. That’s why it is always recommended to wear PPE (Personal Protection Equipment) including safety glasses, chemical resistant gloves, and overalls.

Correct Charger

Lead acid batteries should be charged in 3 stages; constant current (boost), constant voltage (absorption), and float charge. It is vital to select a battery charger that delivers the specified charging voltage and current to suit the battery type. For example, for the Flooded, Absorbed Glass Mat (AGM) and Gel battery types need specific chargers to provide better performance and service life.

Charging Voltage (for manual chargers)

It is crucial to monitor the battery voltage during charging in order to avoid overcharging. Follow the parameters given below in the table for 12-volt lead-acid batteries. When charging 6-volt batteries, half the voltage specifications provided. Otherwise, failure to do so can result in permanent damage to the battery.

Auxiliary Charge Voltage by Battery Type

The recommended temperature during charging is 25°C. If the battery reaches 50°C, stop charging.

Charging Current (for manual chargers)

The recommended safe charging current is 10% of the battery’s 20 hours (Ah) rating. For example, if you want to charge a 100Ah battery, the recommended charger current for this battery would be 10 Amps. Slow charging is the best way to recharge a lead-acid battery. Fast charging a lead-acid battery by increasing the recommended amperes may cause undue stress and shorten battery life.

Constant Current Charging Method (Amps x Hours)

  • Due to efficiency aspects, the charge amount must be more than the discharged amount. This coefficient factor can be between 110% to 150%.

  • The deeper the discharge, the higher the coefficient factor.

Charging Time

It will take about 60% of the total charging time to charge a lead-acid battery to 80%, and the remaining 40% of the time to put the last 20% of charge back into the battery.

The recharge duration is difficult to determine due to variables such as:

  • Depth of discharge

  • Temperature

  • Size and efficiency of the charger

  • Age and condition of the battery

For a guide, refer to the constant current charging method table

Factors Affecting Battery Life

Over time batteries lose their performance, components get corroded, electrical shorts occur, and vibration causes damage. The constant charge and discharge is also the main reason for its failure. Overcharging and undercharging of a battery will also affect battery life.

Battery Inspection

Always check the electrolyte level. If it’s on the top of the battery, then this can be because of overcharging or overfilling. Overcharge condition may be due to incorrect voltage setting, low voltage caused by heat or internal defects, or old age deterioration. Also, inspect for signs of damage. It can also cause a failure, and the battery can be loose in the carrier because of vibration.

Discharged (flat) Batteries

A flat battery should be checked with a hydrometer. A low Specific Gravity reading of 1.220 or less in all cells indicates a discharged battery, and it must be charged before further examination and testing can occur. The discharged condition may be due to a problem in the electrical system (slipping alternator belt, faulty regulator or alternator, high resistance due to corrosion). Internal shorts may also be due to manufacturing defects or shorts through the aging process or vibration damage.

Warning Signs

One of the main symptoms of a failed battery is a slow ability of the battery to crank the engine. Other less noticeable factors, such as changing driving patterns and colder/hotter weather will all affect the life of a battery.


  • Always use an approved battery clamp as vibration can reduce the battery’s life.

  • Many “dead batteries” are caused by having a faulty voltage regulator or simply by lights left on the car.

  • Make sure to test the battery correctly before replacing.

  • In colder weather, old batteries fail often.

  • In hot weather, if the battery is under pressure from air conditioners, it can fail quickly.

Why do Batteries Fail?

Batteries have their lifespan as well, and various factors can cause their failure. These factors are divided into two categories: manufacturing and non-manufacturing faults.

Manufacturing Faults

Typically occur within the first 3 months.

Short Circuits/Dead Cells

Where one cell will show a dramatically lower Specific Gravity (SG) reading than the other cells.

Internal Break

Usually resulting from physical damage to a battery during transportation.

Non Manufacturing Faults

They are often attributed to a problem with the vehicle’s electrical system, its operation or the battery application.

Wear and Tear

Over time, grid metal corrodes, and the active material is lost from the plate after which the battery won’t be able to start a vehicle. The high temperature will accelerate the degradation rates.

Physical Damage

Incorrect fitment, handling, and storage often lead to external damage and subsequent battery failure.

Incorrect Application

Fitting a smaller, less powerful battery or a battery designed for another application can lead to early failure.


Failure to maintain fluid levels exposes internal components and accelerates battery failure.


Occurs when the battery is allowed to stand in a discharged state for an extended period.


Often caused if the alternator is incorrectly set or the alternator voltage control fails.


Short journeys, stop-start driving, or faulty alternators will not fully recharge a battery.


Lights or other accessories left on for extended periods.