Without a healthy battery, your car isn’t going anywhere. Just like your complex body, your vehicle is a sophisticated universe of parts and mechanisms, and there are many reasons why your battery can discharge.
Although jumper cables can be a quick fix, a dead or unhealthy car battery is annoying and leads to inconvenient and costly repair or replacement. But it can also be avoided, with good maintenance and given that you know why your car battery keeps dying.
What happens if you have a weak battery?
The battery is an essential component. To maximize its lifespan and functionality and to ensure a hassle-free driving experience, you need to make sure your car battery is properly charged. When you have a weak battery, the charging system (i.e., the alternator) and the starter will draw excessive voltage to compensate for the battery’s lack of power, so they will be overworked and over time can malfunction.
Therefore, you should inspect and test your batteries as soon as there is the first sign of trouble, charging or replacing them in time. Otherwise, you might find yourself replacing expensive electrical parts, usually without warning.
Main reasons why your car battery keeps dying
Loose or corroded battery terminals
Your car battery can only function properly if the connections to the terminals are intact. All terminals must be free of contaminants and well tightened so that you cannot wiggle them by hand (you must be careful with side terminals, as you can strip the wires and penetrate the casing, causing an electrolyte leak).
Over time, battery cables and terminals are prone to corrosion. Additionally, the terminal connection can become loose. These will hinder the alternator’s ability to charge the battery and power the car, so you might have difficulty starting the vehicle. You could even stall while driving or damage the vehicle’s electronic components.
But don’t worry. Corrosion is an inevitable problem with all types of batteries. Corroded and loose terminals are not a serious problem and can be prevented through regular maintenance. Clean your car battery terminals with a commercial solution and a soft-bristled brush (remember to wear gloves and safety glasses), and a simple but effective trick to protect against corrosion is to add a little petroleum jelly to the terminals. Another simple solution is to apply liquid electrical tape to create a tight seal, but before removing the battery cable, you will need to cut it.
Your battery is just old and needs to be removed
Nothing lasts forever, including your car battery. Depending on how you drive and the climate of your place of residence, car batteries can typically last between three and five years. Once your battery reaches the three-year mark, it’s time to keep a close eye on it.
A number of factors can negatively influence your battery’s lifespan, including extreme temperatures and frequent short trips. If your car battery discharges quickly, even after a jump start, it’s a sign that your batteries are quite old and need to be replaced.
To track your battery’s health and know when it’s time to replace one, you will need a multimeter or a voltmeter, both of which measure the voltage stored in the battery at a given time. The energy to run the car is stored in the battery and is measured in voltage, and the voltage level in a battery is essentially its state of health.
A battery is fully charged when it contains 12.6 volts or more. When a battery drops to 12.2, it is only 50% charged and when it is below 12 volts, the battery is “dead” and must be replaced.
To use a multimeter to test a battery:
- Before using a multimeter to test a car battery, it is important to let the car sit for at least one hour or overnight. This is because the alternator produces electricity and charges the battery, and if the car has been running, the charge from the powered alternator will produce a misleadingly higher number on the multimeter.
- Locate the battery, which is often housed in the engine compartment under the hood, on one side of the engine. Set your multimeter to 20 DC volts by turning the dial to 20 on the “VDC” (Direct Current Voltage) range, which will allow you to accurately measure a battery storing between 0 and 20 volts (you must set the multimeter to a specific voltage range whenever you use it to test something). The multimeter should read 0.00.
- Connect the multimeter’s red (positive, marked “+”) test probe to the red (positive) battery terminal and the black (negative, marked “–”) test probe to the black (negative) battery terminal.
Tip – Knowing your battery’s age: Just like how your car tire deteriorates with age, even when stored safely, your batteries also lose their strength with age, even without much use and proper care. Therefore, when buying batteries, you should always buy a new one that was manufactured within the last 6 months.
To find out your battery’s age, you can check the four or five-digit date code on your battery case cover. You only need the first part of the code, which consists of a letter and a number, for example A20.
The letter is assigned to each month: A for January, B for February, and so on. The number that follows indicates the year: for example, 9 for 2009, 12 for 2012, 20 for 2020, etc. So, “A20” means the battery was shipped from the factory to local battery wholesalers in January 2020.
The alternator is not charging the battery properly
Your car depends on your battery to start and run the engine. But when your vehicle is running, your battery depends on the alternator to help it stay charged. The alternator produces electrical energy from the car’s mechanical energy and uses this electricity to charge the battery as well as to power various electrical accessories such as lights, radio, and air conditioner.
If the alternator does its job correctly, i.e., if it ensures optional charging of the battery, the battery’s lifespan will be maximized. But overcharging or undercharging will shorten the battery’s lifespan. Furthermore, if your alternator is not working properly, it is not charging your battery efficiently, so you might have trouble starting your car.
If the battery is in good condition and if the slow starting problem occurs when the car has been running, i.e., when the engine is warm, the alternator could be the culprit.
Like your battery, you should also test your alternator regularly or whenever you experience a hard starting or no-start problem. They must go hand in hand.
Note that you must always test the battery before you can test the alternator. This is because the battery starts the engine, and once the engine is running, it spins the alternator and this spinning keeps the battery charged. If the battery is too weak, the car won’t run and therefore the alternator cannot be tested. You need to perform two tests on the alternator to check if it is working correctly at idle without draining electrical accessories as well as at a higher speed under heavy use.
- To test an alternator’s no-load voltage: let the engine idle, turn off all electrical accessories that might consume electricity, including lights, dashboard, and stereo. Repeat the battery test above using the multimeter. A good alternator should produce a reading between 13.1 V and 14.6 V when the engine is idling normally. Anything outside this range means your alternator is undercharging or overcharging your battery, which will shorten the battery’s life.
- To test the alternator’s charging voltage to see if it will function correctly under heavy use: Have your assistant rev the engine to 2,000 RPM. Turn on all electrical accessories and reconnect the multimeter. A healthy, robust alternator should read 13.0 volts and above. Anything below 13.0 volts signals a weak alternator that needs to be checked by a professional.
A parasitic draw on the battery
While your engine is running, the alternator is powered and recharges the battery. However, when your car is off, the alternator cannot recharge the battery, while your battery still powers various accessories, including interior lights, clock, and radio.
Most of these usually don’t drain your car battery, but small electrical incidents can still occur and drain your battery. Interior lighting (including door lights) and faulty fuses can be potential sources of extra stress. To avoid such mishaps, often called parasitic drain on the battery, you should make it a habit to turn off all lights and ensure all doors are properly closed and locked before leaving the car, including your trunk and glove box.
Extreme weather conditions
Your vehicle’s battery is also sensitive to extreme temperatures, which is why drivers more often encounter hard starting problems on icy winter mornings and very hot summer days. “Young” batteries with fewer years on them can better withstand cold or intense heat, but older batteries are weaker with age and therefore have less resistance to extreme temperatures, and can even die completely.
According to AAA’s Automotive Research Center, a car’s battery is weakened by about 60% at 0°F and at 32°F, it loses 35% of its strength. Extreme temperatures can cause irreversible damage to your battery and what follows would be a costly replacement.
First, extreme heat can evaporate vital fluids from your battery, thus weakening its charge. It can also accelerate the corrosion process, which will damage the battery’s internal structure and shorten its lifespan.
Meanwhile, extreme cold can freeze a battery. This will cause the sides of the case to swell, short-circuit the plates, and the battery will no longer charge. Lead-acid batteries and lithium-ion batteries are particularly weak in extremely cold weather.
A battery has adequate resistance to cold temperatures when 100% charged, but as it wears out, this resistance weakens. At 50% charge, your battery can freeze overnight at -10°F. During the winter months, starting an engine will consume more current than is needed in normal weather, up to twice as much. This is why you are more likely to have a hard starting problem on icy winter mornings.
Since temperature has a significant impact on your car battery, you should choose a battery suitable for local weather conditions. It is best to consult your owner’s manual as well as a certified mechanic. Batteries specially designed to withstand extreme heat are often labeled “S” or “South,” while cold-weather batteries are often labeled “N” or “North.” In some cases, if you live in hot climates, you can replace your AGM battery with a traditional flooded battery to maximize its lifespan.
Frequent short trips with an old battery
You might know that the more constant-speed highway driving is better for your car in general, whereas a lot of stop-and-go driving in traffic jams would cause premature wear on many car parts. This is also true with your car batteries.
What happens when you frequently take short trips is that when starting the engine consumes a huge amount of power from your battery, the alternator may not have enough time to properly recharge your battery between drives. Over time, this significantly weakens the battery and shortens its lifespan, especially if your battery is already old.
Tips: how to ensure your battery’s good health
Choose the right type of battery for your vehicle
First, to ensure optimal performance and lifespan, you need to get the battery that fits your car. Each vehicle needs a different amount of power and a different size battery, so each vehicle requires a specific battery type. So, you should consult your owner’s manual to find out what type of battery is suitable for your car, or ask a mechanic what is best for your car.
For example, if you often take your vehicle off-road, you need a battery capable of withstanding constant vibrations on rough terrain. Many cars are equipped with AGM to support a growing range of electrical components, and the charging system can be configured specifically for an AGM battery. And in some cases, you can replace your AGM battery with a traditional flooded battery to increase longevity in hot climates (although the flooded type requires more maintenance as below).
Choose a battery with easier maintenance
Car batteries require regular maintenance to stay healthy. One way to save time and better ensure your battery is healthy even if you are not a DIYer is to buy a maintenance-free battery in the first place. If allowed, get a gel or AGM type battery. Thanks to advanced technology, these are sealed and do not require any special attention like flooded lead-acid batteries.
Flooded lead-acid batteries require more maintenance. They lose water during the charging cycle, so they must be topped up with distilled water only every 2 to 4 weeks, as needed, to function properly and stay healthy. Additionally, they must be equalized from time to time to ensure that each cell is equally charged. You can do this by applying a controlled overcharge once every 30 to 90 days.
Perform a load test regularly
While almost all car batteries today are supposed to be maintenance-free, regular inspection and maintenance are still crucial for any machine. It is recommended to test your battery with your alternator (no-load and load tests), preferably at least once a year as soon as it is 3 years old in a mild or cold climate, or once it is 2 years old if you live in a hot climate. This tests the battery’s ability to maintain voltage during use, and the results will tell you when it’s time to replace it.
Useful accessory: float/maintenance charger
All types of batteries are prone to a problem called natural discharge or self-discharge. This is an inevitable process, in which internal chemical reactions reduce the battery’s stored charge without any connection between the electrodes or any external circuit. Therefore, if you need to store your vehicle during the winter or in other circumstances where it will be inactive for a long period, you should invest in a float charger to maintain your battery’s full charge.
Also called maintenance chargers, storage chargers, or trickle chargers, these float chargers prevent excessive self-discharge when your battery is not used for an extended period. To prevent this, the charging rate of a maintenance charge is equal to the battery’s natural self-discharge rate.
Most maintenance chargers have built-in circuits to prevent overcharging so you can leave the charger on 24/7 without worrying about overcharging the battery, although some models do not and can damage a battery by overcharging it. Even though a float charger automatically monitors and charges the battery, it is still recommended to check periodically to ensure everything is still in good working order.
While you’re at it, it’s best to also get a portable battery starter and store it in your vehicle at all times as an emergency tool. These increasingly compact accessories allow you to easily start your vehicle without having to depend on another car.