Whether you drive a gasoline or diesel-powered vehicle, it relies on electricity to start the engine and to operate an array of onboard electronics when the motor is not running. For this reason, it needs a place to store some electricity to power the starter, alarms, stereo and other devices until the alternator comes into play. This place is your vehicle’s battery, which is a compact powerful box that usually houses six galvanic cells submerged into electrolyte.

Not all car batteries are the same. There are three main types of car batteries, including SLI, lead-acid and lithium-ion ones. The first of them is the most common type found in today’s vehicles. By design, it is a plastic box with 6 plates made of lead or lead dioxide submerged into a mix of water and sulphuric acid. The latter reacts with the lead dioxide causing a chemical reaction that generates electricity. Each plate is able to provide up to 2.1 volts, so all together they give a total battery output of 12.6 volts when the battery is fully charged.

Your starter motor and car electronics consume a lot of electricity, so your battery needs to be recharged when not in use. This is the job and responsibility of your vehicle’s charging system. Once the engine starts, your belt-driven alternator begins to supply power to the battery, recharging it to make it ready for its next time operation. An improperly functioning charging system can deplete your battery and cause its premature failure, resulting in inability to start the engine and malfunctioning onboard electronics. The other things that can shorten the service life of your battery are severe weather conditions, driving short distances on a regular basis and leaving your stereo or lights on. Let’s describe them one by one. 

Leaving your lights, stereo or stereo amplifier on after shutting the engine

Your exterior and interior lights, stereo and other electronic add-ons can draw a lot of electricity when in use. Since your engine-driven alternator doesn’t generate current to power the devices and recharge your battery when the engine is not running, the battery can quickly get discharged and even fail completely.

Power leaks

The onboard electronics of a modern vehicle draws some constant current to operate. You may notice that your clock, radio, engine control module, alarm or keyless entry system continue to function when your engine is off. In most cases their total power consumption is pretty low, so you experience no problem when starting the engine. Although, as your battery ages or due to some charging system problems, you may suddenly find your battery depleted and not be able to start the car.

Driving only short distances

Your battery needs some time to be recharged. If you do only short trips on a regular basis with lots of powerful accessories running, your battery’s charge will slowly deplete. As a result, it will not be able to provide enough power to crank the motor next time you push the start button. Such battery failures are very dangerous to the health of your battery because they can cause acid stratification when the acid concentrates on the bottom of the battery. This reduces battery performance and shortens its service life.

Poor battery cables

Loose cables and corrosion deposits on the battery terminals can restrict power flow from the battery and back to it, resulting in improper battery recharging and a lack of power supply to the starter and the rest of the vehicle. This may lead to a dead battery and keep your engine from starting.

Low electrolyte level

Whether your battery is serviceable or maintenance-free, it needs a proper level of electrolyte to function. If it reduces, the battery will not produce enough power to start the engine and run the vehicle’s accessories. 

Your charging system malfunctions

To operate properly, your battery needs to receive the same amount of power that it supplies to the rest of the vehicle. Under normal conditions, your charging system handles this job perfectly, keeping the battery properly charged. However, a loose drive belt, alternator problems or malfunctioning electronics can tip the balance, resulting in a depleting battery.

Severe weather conditions

Low temperatures are an enemy of your battery. They reduce its performance by slowing down chemical processes inside the battery. As a result, it produces less power, while requiring more time to be recharged. Plus, it is easier for the battery to get overloaded due to the use of your heater, headlights, different defrosters and other electrical devices at the same time.

Your battery is at the end of its service life

While many modern batteries can last up to seven years, sooner or later they will fail. If your battery is old or worn-out, it can fail one day. 

Battery jumpstarts

If your starter fails to crank the engine due to a poor battery, you can try a jumpstart using a donor vehicle. If this is the case for you, please follow several simple rules to make sure you have done everything right:

  • You have quality jumper cables and a donor vehicle that is in good condition.
  • Your battery should be as close to the donor battery as possible.
  • The red (positive) cable must be attached to the positive terminal of your battery first. Then attach it to the positive terminal of the donor battery.
  • The black cable must be connected to the donor’s negative terminal and, then, to any bare metal surface under your hood.
  • Start the donor vehicle and let it work for a couple of minutes.
  • Start your engine.

You may need to do several tries to start your engine. If you fail, get in touch with your mechanic for advice.

Battery troubleshooting

There are several charging system components that can mask themselves as symptoms of a bad battery when they malfunction. That’s why the charging system must be properly diagnosed before replacing or fixing the battery. Here is what needs to be checked:

Charging system

We recommend you to check your alternator performance, its drive belt and tensioner as well as all related wiring and charging system components.

Starting system

If your starter, solenoid or relay fails, you won’t start the engine. 

Battery terminals and cables

Deposits of corrosion on your battery terminals and cables can affect power flow in and from the battery. You should disconnect the positive cable and only then the negative one, and clean the terminals with a wire brush and some water. Please be advised that this will reboot your onboard computer and other electronic devices, so you might need to save their setting if possible. Don’t forget to protect your skin and eyes with gloves and glasses to avoid injuries caused by toxic dust.

Check the level of electrolyte

If your battery is not maintenance-free, you could try to top up the electrolyte levels with distilled water to fix the battery. Before doing the trick, you must protect your eyes with glasses and your hands with gloves.

If your battery can't hold a charge, it must be replaced with a quality replacement battery recommended by the manufacturer. If you’re not sure which battery meets the requirements, consult with your mechanic.

How to prolong the service life of a battery

Regardless of your battery’s type and age, you can prolong its service life by following several recommendations:

  • Recharge the battery with a special battery charger from time to time if you live in a climate with extreme temperatures.
  • Try to avoid driving a vehicle with all your accessories running at the same time.
  • If you drive short distances, check the voltage and current outputs of your battery to prevent its depleting.
  • Follow the manufacturer’s maintenance tips.
  • Take care of your charging system and your vehicle.

It goes without saying that we cannot control some factors that affect the life of a car battery. Thus, you can’t change the climate you live in or drive longer distances just in order to charge your battery. However, you can take care of your battery by following the recommendations to keep it functioning as long as possible.