Car Batteries – All Common Problems and Questions People Keep Asking

While a car battery just works to supply your stater motor with power when needed, it's not wise to underestimate the importance of this unit in your vehicle. The problem is that when the battery goes low, you may just get stranded or see your car glitching in all possible ways.

In this article, I want to tell you about the common problems with the 12V batteries in modern cars. And I will also promptly answer common questions people ask about them.

I will link several articles I and my colleagues wrote here, at Cararac.com just for you to have deeper research and knowledge about the importance of batteries in vehicles.

What battery voltage is good?

This is a tricky question. Although the battery is called a "12V battery", when it shows 12 volts, it's bad. It should be about 12.5 volts and the discharge limits may differ for various types of units (like AGM, EFB, or simple lead-acid types).

But this voltage is only good when your engine isn't running. When it's running, even 13.9 volts will be considered low. You will need to see something like 14.3-14.7 volts to conclude that the alternator is working well.

Older batteries will drop in voltage when discharged while EFB and AGM units may keep being 12.3-12.5 volts even at 60% discharge. But any battery reading less than 12 volts should be considered dying or even dead.

If you let the battery sit for a while with no work, it will lose charge. Even in those cases when you disconnect it from the car. This is the nature of any power storage unit in the world.

Car battery voltage highlights:

• Optimal conditions:12.4 - 12.5 volts
• When charging:14.3 - 14.7 volts
• Alarming voltage:less than 12 volts
• Acceptable drop when loaded:up to 10.5 volts
• Fix for low voltage:charging or replacement
• DIY fix:possible
• How much to fix? $0 - $250

Dead 12V battery replacement issues

Modern cars hate it when you disconnect the battery for whatever reason. You may find that your backup camera is dead after you connect the new battery. Also, the instrument cluster may have a glitch or just be off after experiencing issues with the voltage supply.

While some cars may require registering the battery with a professional scanner after installing the new one, some others will just need time. All complicated electronic modules will need to recalibrate and come back to normal work. And no reset or other actions will be needed.

After you replace the power storage unit in your car, wait for a while and let it work. There is a chance that everything will come back to normal after an hour.

Also, if you decide to replace the battery on your own, remember the sequence: the negative terminal is first to disconnect and last to connect. It's important, otherwise, you may burn the car's brain. To avoid all kinds of problems with battery replacement, you may also need to read the driver's manual for your car.

Dead car battery replacement highlights:

• Critical voltage:less than 10 volts
• Average battery age:4-5 years
• Tools needed:set of wrenches
• Timeneeded:15 minutes
• If done incorrectly:electronic glitches, frying ECU, no crank-no start
• DIY fix:possible
• How much to fix?$150 - $250

Most common battery problems

Although it's hard to list the symptoms of battery issues, they may happen with any car. I've written an article about the Acura RLX issues with the battery which seem to be more common than in other cars. Also, in the BMW X3, it's pretty common that the 12V battery may be drained very fast.

So, even luxury cars that cost much more than average develop issues with power storage units. Also, overall reliable vehicles like Volkswagen may surprise their owners with issues that eventually depend on the health of the battery.

One more vehicle that surprised me was the Honda Civic with its monstrous power supply problems.

One more thing to pay attention to is that in modern hybrid cars, 12V batteries seem to have much more common issues than in ICE-powered vehicles. The Toyota hybrid systems prove this.

Common problems with 12V batteries highlights:

• Possible reasons:battery age, driving conditions, drains, long sitting, electrical problems
• Types affected:all types
• Average age:4-5 years
• Most commonissues:low voltage, no crank, battery light, glitchy electronics
• Can you drive?only if it starts
• DIY fix:possible
• How much to fix?$150 - $250

Auxiliary batteries and their problems

Many cars still have just one 12V power storage - it may be located in the engine bay, or sometimes in the trunk as in some Volvo and BMW vehicles. But a lot of modern vehicles have additional auxiliary batteries.

In some driver's manuals, you will see that it's also called a start-stop battery. But this unit holds more responsibilities than powering your vehicle when start-stop is in use. It may also power some safety features and communication equipment. So, this unit is important.

Auxiliary battery highlights:

• Purpose:start-stop, auxiliary power source
• Average lifespan:3-4 years
• Types:AGM, EFB
• Location options:behind bumper, in trunk, near main battery
• Reasons for failure:age, drain, loose contacts
• DIY replacement:possible but may be complicated
• Average price:$100-$180

Car battery is completely dead

If your vehicle's battery is completely dead, it means you will not be able to enter the car as you usually do - the doors won't open. Of course, the engine won't crank and even the lights will not go on when attempting to start the car.

I've seen cases when brand-new car batteries were dead after a week or two of use. This usually happens because of bad drains or problems with the alternator or voltage regulator.

Also, if the power storage in your car goes bad after just one year of use, you should look for minor drains - this is not a good behavior.

How to recognize that the car battery needs replacement? Well, if it completely dies after turning the car off or jumping doesn't help you get it back to life, then the unit is probably dead. You may try to charge it with a tender and if it doesn't take the charge, you may be sure you need the new battery.

In a lot of cases, long sitting kills car batteries. These units tend to discharge to a critical point when not in use and this leads to them dying really fast - about one month may be enough.

Dead car battery highlights:

• Average lifespan:4 - 5 years
• Voltage range:less than 10 volts
• Symptoms:no crank, no lights
• Reasons:complete discharge, age, hard use
• Prevention:regular charging
• DIY fix:possible
• How much to fix?$0 - $250

Fob battery problems

While the majority of problems are connected to the 12V battery, there are a lot of mysterious issues with the fobs.

For example, the Land Rover smart key may simply stop working after you replace the battery in it. Why? There are reasons for this described in my article.

Actually, you can replace the battery in the key fob on your own or find a place where a professional will do that for a couple of dollars. Proper replacement always helps.

Fob battery problems highlights:

• Average lifespan:9-12 months for smart keys
• Battery type:depends on the fob
• Price for the battery:$1 - $20
• DIY replacement:possible
• Key registering:not needed
• Time for repair:15 minutes
• Price in dealership:$50 - $100

Battery life problems

Older lead-acid batteries are still used in budget-friendly vehicles but the world turns to AGM and EFB units. They usually last 3-4 years and then require replacement. You can try charging them once but they may fail to take the charge.

Also, a lot of car owners prefer installing gel units like Optima while the benefits of their use are not proven. Their lifespan may be up to 5 years but the price is quite high.

Hybrid vehicles use, along with simple AGM or EFB units, the Li-Ion battery packs. They are of smaller size for mild hybrids while PHEVs have much larger packs that can act as electric car power storage units. Li-Ion packs should live at least 10 years or longer than that. It can happen faster in some vehicles due to driving conditions.

You may charge the 12V battery in your car but there is a limitation of the charging sessions it can survive.

Battery lifespan highlights:

• Average lifespan:4-5 years for 12V,10years for Li-Ion
• Average price:$150 - $250 for 12V, $1,000-$4,500 for Li-Ion
• Reasons for death:deep discharge, constant drains, age
• Prevention:regular charging, good contacts
• Ways to fix:charging, replacement
• DIY repairs:possible

Battery drain reason in a car

While age is the most common reason why you may need a new car battery, drains are there to shorten its life significantly.

One of the most common reasons for drains is bad use of the vehicle. For example, you may listen to the music when the engine is off. Also, bad relays that occasionally turn on things in your vehicle when not needed, may be the cause for drains.

Leaving the vehicle unlocked may let some electronics work instead of going to sleep mode. So, it may also drain the battery significantly. While many think that the anti-theft light is the source of the big drain, it isn't really. It only consumes a tiny bit of energy. But if you leave the vehicle for a month or more without any work, even this light will do its bad job.

Battery drains highlights:

• Level of importance:high
• Methods to locate:disconnect everything that can cause drains
• Consequences:dead battery
• Prevention:driving style adjustment, no extra equipment
• DIY fixes:possible but complicated
• Price to fix:$100 - $600

Jump-starting car battery

While jump-starting can save you from being stranded, this is a non-recommended way to treat batteries. You need to be careful as incorrect jumping may kill the electronics in your vehicle.

First of all, make sure the jumping cables are working and are of proper quality. If they aren't working, you may need to check the connection between clamps.

Then, connect the positive terminals of both cars. After that connect the negative terminal of the donor vehicle to the bear metal part on the suffering car. Start the donor car and wait for some time. Try starting the affected vehicle.

You should know that jump-starting is possible with another car or with the car battery booster - no wall outlet will help you in this unless you have the proper equipment.

Jump-starting batteries highlights:

• When needed:no crank issues
• Time consumed:15-20 minutes
• Toolsneeded:jumper cables or booster
• Risks:car electronics may suffer, battery may die
• DIY solution:yes
• Price:$0

Charging the car battery

If you want your battery to live longer, it's obvious that you need to charge it from time to time. This is one of the possible ways to prolong its life and also save yourself from getting stranded unexpectedly.

You should know how the battery charger works. Different types of units require various charging patterns, so it's important to choose the proper tender for your equipment.

Also, it's not that quick thing. You will need to charge the low battery for at least 10 hours or so. Quick charging with high voltage will quickly kill the unit. The optimal voltage is between 14 and 14.7 volts with some spikes that the good charger is programmed to form.

Car battery charging highlights:

• Critical voltage:lower than 12 volts
• Target voltage:12.5 volts
• Charging voltage:14 - 14.7 volts
• Charging time:defined by tender
• Risks:battery death
• DIY solution:yes
• Tools needed:charger, power socket
• Price:$1

General battery questions answered

A lot of car owners ask if the battery voltage should fluctuate when the car is running. The answer is yes, this is possible as the smart charging system may stop sending power to the battery that is fully charged. But if it drops lower than 12 volts, this is a sign of drain.

Also, when disconnecting the battery, drivers don't know if only disconnecting the negative terminal will do the job or if both should be disconnected. Actually, the negative is enough. All the systems will be cut off and reset.

And if you disconnect the battery, will it unlock the doors? If the doors are locked, no, they will stay locked. You will need to use the manual key to unlock the doors.

The fusible link between the battery and alternator is almost a myth in cars. While some have it, some don't. You just need to look into the driver's manual to find out.

Car battery issues highlights:

• Possible reasons:battery age, driving conditions, drains, long sitting, electrical problems
• Types affected:all types
• Average age:4-5 years
• Most commonissues:low voltage, no crank, battery light, glitchy electronics
• Can you drive?only if it starts
• DIY fix:possible
• How much to fix?$150 - $250