Car Battery Warning Light

Just as changing engine oil is said to be the lifeblood of a car to keep it running efficiently, it is equally critical to have a fully charged and healthy battery.  Without a well-maintained battery, you could find yourself stuck at an inopportune time, leaving you stranded in bad weather or causing you to miss an important meeting or function.  But while most people understand the importance of their battery, many are unaware several simple factors affecting battery health and long life.

| How Long Do Car Batteries Last?

All the above batteries have advantages and disadvantages, but your type of car and how you use it will help determine what type of battery is required.  Most automobiles will perform well with the OEM battery included with the car upon purchase.  But regardless the battery type, each battery has specific lifecycle times.

Wet cell car batteries generally last four to five years.  The length can be extended or shortened based on temperatures where the battery is exposed to extreme heat or cold and where the climate systems put excess strain on the battery causing more frequent charging.

VRLA car batteries can last between five and ten years depending on plate thickness and materials used.  This also contributes to their higher cost.  Temperature extremes may affect the life of these batteries more so than traditional wet cell batteries.

Extreme temperatures effect the life of car batteries regardless of technology. As temperature increases so does the chemical process within the cells that produce the energy. All batteries are designed for an optimum operating temperature, which will be around 25c. Any ambient temperature that is significantly out side of this will have a detrimental impact on how long the battery lasts.

In addition in hotter or colder temperatures the car and its air conditioning systems will be working harder, as they heat or cool the air for the occupants. This puts additional work on the battery that will shorten its life.

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| Car Battery Voltage

Most car batteries are made of six cells, each consisting of 2.1 volts.  So, a fully charged car battery voltage should be 12.6.  But conditions and usage can have a dramatic impact on the available charge held within the battery, thus increasing the risk of not being high enough to turn the engine over.

The chemical processes that happen inside the battery to produce current, are slowed down when the battery is cold. When the outside temperature reaches or drops below freezing point, the current available to start the car drops by 40%.  Likewise, an older battery will lose its ability to hold full charge until the day comes when it can no longer provide enough current to start.

Car Battery Voltage Chart showing the voltages of a car battery at different stages of charge and use

| Car Battery Maintenance

Many of today’s batteries are sealed and require little to no internal maintenance in their lifecycle.  However, wet cell car batteries can still be found.  Wet cell car batteries need topping up with water on occasion.  For those older batteries, distilled or deionized water should be used to protect the cells as there are no impurities.

For sealed or no maintenance batteries, there are steps that can be taken on the outside of the battery to help maintain the battery’s connections and ensure long battery life.  Batteries can be regularly cleaned with a baking soda and water solution to keep corrosive materials from collecting and interfering with the battery cables.  Cable connectors can also be cleaned with a wire brush and tightened regularly to maintain good connection with the terminal posts.

| Causes of Reduced Car Battery Efficiency

Once a car is started, systems requiring electricity are supplied by the alternator.  In an optimally balanced and maintained engine, the alternator can supply those electrical needs and have enough spare energy to recharge the battery.  This is known as the “duty cycle” where the discharge on engine start is followed by a recharge from the alternator.

However, there are a few things that can affect the ability to recharge fully that could lead to long-term damage or early retirement of the battery:

Short Distance Driving with Heavy Power Use

In modern towns and cities where driving distances are often short and traffic is stop and go, batteries may not have the time to recharge fully when coupled with heavy power usage from a large array of accessories such as wipers, heaters, air-conditioning, stereos and charging of plugged in accessories.


Sulfation occurs as a chemical reaction when power is taken from a battery. As the battery recharges, this chemical process can be reversed.  However, in the case of excessive discharging there is a danger that the sulfation will crystallize and remain on the plates of the battery.  Over time, this will inhibit the battery’s ability to maintain an adequate charge.

| Car Battery Not Holding Charge

If a car battery appears not to be holding a charge then it is worth discounting the following causes before you replace it.

Parasitic Loss

Parasitic loss is when an electrical fault or an electrical device that remains on, drains the battery when the car is turned off. To test for parasitic loss, you can remove the battery and fully charge with a car battery charger, you may need to do this overnight to ensure it gets a full charge. Then wait a few hours and test the battery again. If it has held its charge, then the battery is OK, and you could have parasitic loss.

These drains can often be identified through trial and error by powering them down, or removing peripheral devices, and repeating tests after charge until the culprit is identified.  Failing that take it to a professional to get checked out.

Faulty Alternator

It is the alternator that charges the car battery when the car engine is turned on, as well as powering the cars electrical systems. To test for a faulty alternator simply conduct the test above, but this time with the car engine running. Whilst the engine is running you should get a voltage of somewhere between 13.8V to 14.4V. If you get a reading either side of this range and you need to get your alternator checked out.

Loose/corroded/dirty battery terminals

Loose fitting, corroded or dirty battery terminals can cause a voltage drop and make it appear you have a faulty battery. To test for a voltage drop on the terminals follow these steps:

      1. Set the multimeter dial to “DC Voltage”.
      2. It is important to disable the car’s ignition system to prevent the car starting while testing. This can be done by removing a fuel pump fuse or by disconnecting the ignition coil.
      3. Using the red probe, touch the battery’s positive post.
      4. Then, use the black probe to touch the terminal ending on the same post.
      5. Have someone turn the ignition on inside the car.
      6. If the meter reads 0.5 Volts or more, the terminal may need to be cleaned to clear corrosion and dirt or tightened if loose
      7. Now perform the same test again this time with the negative black probe on the black battery terminal.

Dirty Battery Lid

An accumulation of dirt and moister on the battery lid can result in “tracking” across the top, causing a voltage leak. It is a good idea to clean the battery lid if it is dirty, but to check if this was the cause of a flat battery then perform this test:

      1. Set the multimeter to a low voltage setting, place the red positive probe on the positive terminal and the negative on the dirty battery lid.

If the multimeter registers any voltage, not matter how small then this indicates tracking and a voltage leak.

Simply clean the battery lid to rectify this issue.

| Car Battery Monitors

There is nothing worse that coming to start your car and ……… nothing. Or the sound of an engine struggling to start. Often this is caused by a flat, or undercharged battery. In modern cars this doesn’t happen often and there are internal warning systems should the battery start to under perform.

But should your car be older, or you simply want a sure way of seeing how your battery is performing, then you can buy a car battery monitor.

These car battery voltage monitors are often Bluetooth devices that are permanently attached to the battery and connect to an app on your phone. When you are in range of your battery you connect to the app and read off the battery voltage and a performance history of the last starting events.

Some devices will push notifications to your phone in the event of poor performance, so you don’t even need to remember to connect you app to the battery monitor.

By monitoring the battery you can detect early signs of poor performance, which then allows you to replace the battery before it fails.

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