Can You Drive a Car with a Low Battery?

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Low battery diagnostic light indicator on the instrument cluster close up

Battery problems are a quick way to ruin your morning. After struggling to get your car started, you might wonder how long it will even last. More importantly, can you even drive a car that has a low battery?

The quick answer is that you definitely can drive your car with a low battery. I wouldn’t suggest doing it. Your car runs the risk of stalling and losing power on the highway which is really dangerous. However, you can definitely drive your car to a nearby mechanic to get it fixed. The alternator will be doing all the work instead of the battery.

In this short guide, I’ll answer your question. I’ll walk through some of the basics of a battery, explain what issues to keep in mind, and determine whether or not your car is safe to drive with a low battery.

The Role of Your Car’s Battery

The battery of your car is the only source of electricity. That means that anything that needs to be electrically powered while you drive will get its charge from the battery.

This includes things like your HVAC, radio, lights, and power-adjustable seats. In addition, it also keeps your car’s engine running.

If you hypothetically remove your battery while your car is running, the engine will shut off and your car will stop running.

How the Alternator Factors in

Your car’s battery is always discharging as long as your car is running. How does it stay charged, then? It’s not like you’re plugging your gas-powered car into an electrical outlet at the end of the day.

How a car battery charges the engine starting system and alternator

This is where the alternator comes in. An alternator converts mechanical power to electrical power. As your car runs, the alternator is spun. This spinning creates electricity which is then siphoned back into your battery.

In a normal situation, the alternator and battery are working together. When either of these two components fails, the other one will take over and do all the work. The difference is that a car with a dead alternator will always result in a dead battery after enough driving.

Under the hood, your battery is always being charged whenever the car’s moving (as long as the alternator is working). This idea is going to be very important in a second.

What Does a Low Battery Mean?

As you might know, your car battery uses a chemical process to create electrons which turn into usable electricity. Inside your battery is a combination of lead, acid, and metal to allow this chemical reaction to take place.

The lead eats away at the metal which frees up an electron to move and power electrical components in your car.

Digital illustration of a low battery charge in the car

This process only works as long as there’s enough material inside your battery. The problem is that the chemical process will remove this material for as long as the battery is being used.

Over enough time, your battery will run low on acid and lead. When this happens, it can’t create enough electricity to do its job.

The amount of remaining lead and acid can be roughly thought of as the level of your battery. As the materials dwindle, your battery is “low”.

KONNWEI KW208 12V Car Battery Tester, 100-2000 CCA Load Tester Analyzer for Car Truck Marine Motorcycle SUV Boat

KONNWEI KW208 12V Car Battery Tester, 100-2000 CCA Load Tester Analyzer for Car Truck Marine Motorcycle SUV Boat
KONNWEI KW208 12V Car Battery Tester, 100-2000 CCA Load Tester Analyzer

This is essentially what your battery tester is checking for as you determine the health of your battery. Instead of measuring how much acid is left, the gauge is checking how much voltage is being generated, which is a byproduct of the remaining lead and acid.

Once your battery completely runs out of these internal materials, it won’t generate any electricity. This is constituted as a “dead battery”. In your case, you’re close to this condition but you still have enough juice to get the car running.

The Biggest Toll Is Getting the Car Started

I recently wrote a guide for starting a car with a low battery, and you’ll notice that it’s not so easy. Initially starting your car involves creating a spark and starting a smaller motor which eventually turns the main engine on.

It requires a lot of electricity. That means your battery needs to have enough juice to get things started.

Starting a car

Once this massive spike is delivered, the battery will coast at a much lower level. More importantly, the alternator will kick on once your vehicle is running.

Why is this important? There are two factors at play here: your alternator will finally start running, which back-feeds your battery and starts recharging it. It also means that it’s easier to keep a car running, even if your battery is low (as long as you can start the car).

Can You Drive a Car with a Low Battery?

Yes, you can drive a car with a low battery. It’s going to be tougher to get it started, but it should continue running as long as your battery isn’t completely dead.

In this scenario, your alternator is doing most of the heavy lifting. It can create all the current that your car needs to keep going.

However, there’s no guarantee that your car will keep running. All it takes is for you to turn on your headlights and your car’s demand can be higher than what the alternator can supply. Just like that, your car can stall out and you’ll lose power.

Alternator or Battery: Only One Can Be Bad

It’s worth pointing out that this scenario is contingent on either your battery or alternator being healthy. In the case where both your alternator and battery are both bad, you won’t get very far.

New car generator alternator and belt installed on tensioned shaft

If your battery is very low but your alternator is fine, then your car will rely on the real-time current supplied by the alternator.

Tips for Running a Car with Low Battery

Even though your car is running, you should remember these tips. They’ll keep you safe moving forward.

Just Because It Starts and Drives Doesn’t Mean It’s Fixed

Once your car is running, that doesn’t mean that your low battery is solved. Remember, this is happening because your battery is running out of lead and acid — two materials that are necessary to keep generating electricity.

Once you fully deplete these, your car won’t run anymore.

Turn Off Most Electrical Components

In this equation, there are two sides: the electricity your alternator can generate, and the electricity your car’s electrical components need.

Close up of the entertainment system touchscreen center dash interior infotainment apps

You always want to generate more than your car needs.

To do this, you’ll need to turn off most of the components around your car. Turning off your HVAC and radio will free up a lot of the current demands. Avoid using your windows, adjusting your powered seat, or moving your powered mirrors.

This Isn’t a Good Idea

Just because your car can run doesn’t mean it should. If your car needs too much current and overpowers the alternator, your car will turn into a brick. Your gas pedal won’t work, you’ll lose power braking, and your power steering will stop working.

That means that you’re sitting in a piece of metal that you can barely steer or stop. If you’re on the highway, this is a really dangerous scenario.

Immediately Repair Your Car

I would consider this fix an “emergency situation”. After getting your car started, your next stop should be a place where you can repair your car.

Since it’s just a battery replacement, you can easily handle the repair on your own. You just need to buy a new battery, so your trip should be right to the auto part center.

Car Battery Replacing

If you’re not comfortable swapping out a battery, then you should drive right to the mechanic.

Pushing your luck with a dying car battery is never a good idea. It’s inevitably going to fail, and it will probably be when you least want it to happen.

You Might Stall When You Stop

The alternator works best when your engine has a load on it. This happens when your car is in motion, not idling.

It’s very possible that your car will drive perfectly fine until you come to a stop. When this happens, your alternator is suddenly not making enough electricity. The car’s demands will be higher than what the alternator can provide, so your car will just stall.

The kicker is that this isn’t an easy problem to fix. Now, you’re at a red light or stop sign with a car that won’t move. It also won’t start just by turning your key, you’ll have to give your car a slow drip or jump to get started again.

How to Fix a Low Car Battery

In the case where your alternator is fine, but your battery is low, your only option is to replace the battery. It’s a straightforward process and doesn’t take too long.

Lisle 57850 Battery Carrier

Lisle 57850 Battery Carrier
Lisle Battery Carrier

Start by fully disconnecting your battery then remove it from your car. Batteries are pretty heavy and uncomfortable to grab, so I always use a battery carrier.

Grab your new battery and install it into your car. Connect the wires and hook up the leads. Use your battery tester to ensure the generated voltage is okay before considering the job done.

Conclusion

I just covered the fact that you can drive a car with a low battery. It’s still not the best idea to do, but it can help get you out of a bind and avoid towing your car somewhere. For more of your car questions answered, check out the rest of my blog. I also have a list of recommended products that can help you out.

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Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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