I remember the day that I walked into my garage, got into my car, pressed the engine start button and nothing happened. I immediately knew that the battery was dead and quickly thought back to the day before. I had pressed the ignition button to start the engine while parked at a mall and nothing happened. I pressed the starter again and this time the engine came to life albeit a bit slower than usual. I didn’t give it a second thought.
That, as it turned out, was my hint that the battery was on its last legs.
Why don’t cars have battery meters is a question I have asked myself in the past but never bothered to actually research. I mean, we have access to fuel and fluid levels, inside and outside temperature and other warning lights. My car gives me a (!) sign when the temperature drops close to freezing to warn me about icy conditions. But no battery level indicator. I finally decided to do some research and get to the bottom of it while my car was stuck in my garage unable to move.
Battery meter readings need to be interpreted which not all people can do. Modern cars use a simple battery light to indicate a problem with the battery charging system whether a dead battery or alternator problem that quickly lets the driver know they need to get the car checked immediately.
Battery meter readings are not what you think
Most car batteries are advertised as 12 volts but when new they may measure as high as 13.2 volts. A 12 volt car battery isn’t measured the way you may think in terms of when it is considered dead. A car battery doesn’t drain down to 0 before needing to be replaced. The actual range of charge between a fully charged and dead battery is only around 1.5 volts.
Here are various voltage levels that show you how a car battery discharges.
12.5 volts – 12.9 volts: Indicates a fully charged 12 volt car battery. A new battery will typically measure 12.5 volts or higher. It may go as high as 13.2 volts but overcharging a car battery can lead it to swell and bulge.
12.4 volts: At this level, the battery is considered to be 75% charged so it has already lost 25% of its charge. The battery is still fine to use
12.2 volts: At this level, the battery is considered to already have lost 50% of its charge and thus still has 50% of its charge left. The battery still works but its life is half over.
12.0 volts: At this level the battery may already have difficulty starting the engine of the vehicle. At 12.0 volts the battery is considered to have 25% of its charge left. Once you get here you’re get close to the end of the battery life.
11.4 volts or below: The battery is fully discharged and needs to be replaced. When you allow a battery to fall below 11.4 volts while in use, it tends to damage the battery permanently.
Battery gauges only tell part of the story
The reason why a battery meter in a car doesn’t necessarily help the average person is that unless you understand how a battery drains, you may think that a battery showing (for example) 11.4 volts is in great shape when in fact it is dead.
Further, in order to measure the capacity of a car battery you’d need to load the battery and then let it run down. It’s simply not something you can do.
Add that to the fact that having a battery gauge would give most drivers a false sense of security when they misinterpret the reading. This leads us to why cars are instead built with a simple amber or red Check Battery or Check Engine light:
A battery warning light lets the driver know they have a battery or charging system problem of some kind and should get the car serviced as soon as possible.
Quick overview of car battery stats
Average car battery lifespan
A car battery will last 3 – 4 years normally and 5 – 6 years at the high end. If you take frequent short trips and live in an area with very hot summers and/or very cold winters your battery will tend to require more frequent replacement. Higher end cars with plenty of onboard computers and features that require memory such as GPS navigation systems and memory seat settings always use a bit of power even when the car is not being used.
Average car battery lifespan when the car isn’t being driven
A car battery can die with as little as 2 weeks of not being driven. A newer vehicle and car battery may last as long as 4 weeks without being driven. Higher end expensive cars with more battery-using features are often at the lower end of the spectrum.
Average car battery replacement cost
$45 for a cheap entry level battery and up to $250 for high performance model is typically what you’ll pay for the battery itself. While gas vehicle batteries are generally easy to change, some higher end cars and diesels require computer diagnostics for battery swaps so you might be better off just visiting a pro and letting them do the job.
Some higher end German cars have the battery in the trunk which has benefits (more on that below) but can be difficult to access.
Average cost to tow a car with a flat battery
For a short trip of a few miles, you will probably pay up to $125. For longer trips the cost could be as high as $275 and that’s just for a simple tow and no extra work pulling you out of a ditch, etc. If you belong to AAA or CAA or another auto club, you may get a discount or 1 free tow per year. Tow companies may charge a hook up fee of up to $100 once they arrive on site to tow you and charge mileage on top.
Amps required to start a car engine
100 amps – 130 amps are required per engine start. The older the battery, the more difficulty it will have over time to summon enough energy to start the engine cold.
Idling a car for 15 minutes
Only replaces about 3 amps – 4 amps to your battery. So idling your car in the driveway will not recharge your battery and may do more harm than good.
Ways to recharge your battery
Drive your car at least weekly for 15 minutes or more to get the Revolutions Per Minute (RPM) above 1,000 RPMs to recharge your battery. You can also buy a Smart Car Battery Charger to regularly recharge the battery to keep it fresh.
Hot weather and car battery lifespan
Car batteries die faster in very hot weather (hot summers) because the heat helps to evaporate battery fluids thus weakening its charge.
Cold weather and car battery lifespan
Car batteries also die faster in very cold weather (icy winters) because the engine needs more battery power to turn over when cold and because accessories like heaters, defrosters and heated seats are in constant use.
How does a car battery and charging system work?
Your car’s power system consists of two main pieces that you’ll hear about:
Battery: The car battery provides the charge to the starter motor to start the engine of your car. The battery also powers (at a low level) certain features in your car even when the car is not being used that require memory like your GPS, alarm system, preset seat settings and the like.
Alternator: Once the engine is running, the alternator charges your battery and powers the electrical system of your car while you’re driving.
So when you have the Check Battery or Check Engine light come on, your car’s computer system system is telling you something is wrong that should be addressed. Maybe it’s the alternator. Maybe it’s the battery. Perhaps it’s something else.
If you had a simple battery meter that measured the battery’s charge, not only would you have to interpret the reading, you wouldn’t necessarily know that something is wrong because all the gauge would do is measure the battery charge.
How often should I drive my car to keep the battery charged?
Modern car batteries can die after not being used for around one month. Some higher end cars can last around 2 weeks of not being driven before the battery dies due to onboard computers and other devices that use power even when the car isn’t in use.
A good rule of thumb: Drive your car at least once per week to keep the battery charged. While idling it in your driveway is better than nothing, an actual drive of 15 – 20 minutes is ideal to give the battery enough time and engine speed to recharge properly.
This is even more important in winter when battery usage is higher due to cold temperatures which affect only the engine during starting but heaters and defrosters that are in constant use.
Car batteries are in constant use even when the car isn’t driven
Modern vehicles have many features and benefits that use the battery even when the vehicle is not in use. Think about the features you have in your vehicle:
- Onboard computer systems which uses the battery at all times.
- Car alarm system which also uses the car battery when the car is idle.
- Memory features for seat positions, radio settings and climate controls.
- Your AC adapter that you use to charge your cellphone and may leave plugged in.
- Your radio and heater which you may use while the engine isn’t running.
Even when the car isn’t in use, a small amount of power is used at all times. For a new battery it’s not a big issue but as the battery ages and drains, it becomes more of a concern.
With an old battery, leaving the radio on for even several minutes while the engine is shut off can put the final nail in the coffin of your battery.
Accessing your car battery for inspection and replacement
Modern vehicles often hide the battery making it a bit more work to replace yourself, if you’re up to the job. The more expensive the car the more likely you will need to get the car serviced and pay to have the battery replaced.
Knowing where your car battery is located is the first step in the process. While most vehicles have the battery underneath the hood where the engine is located, some vehicles – think German manufacturers like BMW, Mercedes, Audi, etc – put the battery in the trunk.
What are advantages of having a car battery in the trunk?
- It’s practical: The battery is away from the hot engine when it’s in the trunk. We already mentioned that heat kills batteries quicker by evaporating the fluids.
- Less vibration. By putting the battery in the trunk it’s also at the back of the car and away from natural vibrations from the engine and bumps on the road near the front tires.
- It saves space: Modern engines take up space whether because they are large or hybrid so putting the battery on one side of the trunk underneath where it can’t be seen makes it unobtrusive and you don’t lose trunk space.
Once you locate your battery you can inspect it every so often to look for clues of damage. Check the battery cables for corrosion. Check to see if the battery housing is damaged or misshapen in any way.
Pay attention to your battery’s warnings
Pay attention to your vehicle and don’t ignore the signs! I didn’t pay attention to the fact that the day before my car battery died, it gave me a hint it was on its last legs: I pressed the start button and nothing happened. I also recalled that the second time I pressed the starter, it did start but it cranked slower than usual. I should have known something was up, especially since the battery was several years old.
But replacing a car battery is only something you do every few years so it’s not something we generally keep an eye open for, do we? We just need to look for the clues that our car battery is nearing its replacement date.
What are the other clues?
How to tell your battery is due for replacement
The clues that your vehicle battery is close for replacement include:
- The battery is over 3 years old. Once it exceeds three years of age, the fourth, fifth and (if you’re lucky) subsequent years are a toss up: Your battery may last that long or suddenly die.
- Check engine/battery light comes on: Some cars have different color codes for the Check Battery light ie. Amber light means battery is ok but needs to be recharged ie. the car should be driven to recharge the battery to a minimum operating levels. Red light means the battery is dead and needs to be replaced.
- Slow engine cranking. When you turn the ignition on and the car engine turns over slower than usual, this is usually a sign that your battery is weak. Just like I experienced but ignored.
- Damaged battery: If your batteries cables are corroded or the battery case is damaged or misshapen, the battery’s ability to function properly will be impaired.
- Dim lights: If you notice your headlights or dashboard lights look dimmer than usual, this is a sign that your battery is weak.
- Slow wipers: Your windscreen wipers move slower than usual.
- You live in a cold winter environment. Cold temperatures especially in winter require more power to start a cold engine. Plus you then use battery-sappers like the car heater, defroster, heated seats and steering wheel and all the nice amenities that modern vehicles have.
- You drive mostly short trips: If you drive your car on mostly short errands, the engine battery doesn’t have enough time to properly recharge. A 10-15 minute trip minimum is usually required to recharge a battery so mostly short driving trips and starting and stopping of the engine doesn’t help.
- You use the other battery-sapping features in your car. When you recharge your cellphone or tablet or have a DVD player for your kids, they all help to drain your battery quicker than you may think.
How to extend your car battery life
- Run your car at least weekly for at least 15 minutes. Idling your car in park may do more harm than good as you need to be above idle speed for the battery to have a chance to recharge.
- Don’t use accessories like the radio or heater/AC unless the engine is running.
- Store your car in the garage and park it in the shade when possible during hot sunny days to avoid overheating the battery.
- If you have more than one car in your household and one car takes short trips only, change it up and take that car on the trips of 15 minutes and longer to recharge the battery.
Hot weather kills car batteries
Direct sun and hot weather hitting the metal hood of your car can decrease the lifespan of your battery. Battery fluids can evaporate in hot weather which decreases its efficiency. Plus you tend to use your car AC which is a big energy drain during hot summer months.
Cold weather kills car batteries
Cold wintry weather is hard on the battery. Cold engines require more cranking to start and there is more stress on the engine when the engine oil and other fluids are cold and thick. Then you turn on the front and rear defroster, heater, steering wheel heater and seat warmer to warm the car up. Then you turn the radio or CD player on and charge your cellphone on the drive. It uses a large amount of power and puts stress on the battery.
Final thoughts on car battery lifespan
Have you ever been to a car dealer and seen brand new vehicles inside the showroom with battery chargers hooked up to them? How can a vehicle’s battery die if the car is just sitting there not being used?
Answer: The battery dies because the car(s) is just sitting there not being used.
With COVID and various lockdowns that saw people working from home and not nearly driving as much, car batteries – even newer ones – risked dying quickly after only a few weeks of not being used. I experienced this myself as I went 2 months without driving our lesser-used car and suddenly realized I should probably take it for a drive to recharge the battery.
Sure enough, I pressed the starter and while the engine started immediately, the amber Check Battery light came on. Amber means it’s a warning. A red Check Battery light means the battery needs to be replaced so I figured I had caught the problem in time. I took the car for a 20 minute drive and upon returning home, shut the ignition off and then immediately restarted the engine. The Check Battery light had turned off.
Running a car for 15+ minutes at above idle speed helps to recharge the battery. This means you can’t just start the engine and leave it running in your driveway for 15 minutes. It’s generally recommended that you should drive your car even at a low speed and the battery will have a chance to recharge. Run it for longer than 15 minutes if you can.
This won’t work forever. A car battery can only recharge so many times before it does eventually need to be replaced but running your car regularly does help to extend the battery life.
Summary
There’s an old saying in sports: It’s better to trade a player one year early than one year late.
A vehicle battery is similar: You’d rather replace your battery a bit early than a bit late and have to deal with a dead car stuck in your driveway or garage. Or worse, get stuck dozens or a few hundred miles or kilometers away from home.
Once your battery hits the three year old mark, keep an eye open regularly for clues that it is approaching its end of life. Once it hits four years or more, really be on the lookout. Be more vigilant when you live in a region that gets cold winters which sap battery levels quicker.
And how did I get my car and its dead battery out of the garage? My neighbor across the road happened to have a plug in battery charger that I was able to use to get enough juice back to start the engine and back it out of the garage. I then drove to Costco to buy a replacement battery in my other car with a functioning battery.
In that regard, consider getting a portable battery charger and leave it in the trunk of your car so you’re ready to go in the off chance you do experience a flat battery at the most inopportune time. It’s a device that will pay for itself with just one use.
When you take your car in for servicing, get them to test your battery levels and get a printout to take home with you. If your battery is getting low it’s good to get it replaced before it’s too late especially if winter is approaching.