How Long Does A Car Battery Last Without Driving?

That’s a rough guide, but you must also understand that that’s far from set in stone.

Each car is so different, and each car battery is so different.

In the UK, weather has the least effect out of the factors mentioned. Our weather is relatively mild, we’re not prone to long period of extreme weather. Extreme temperatures tend to be short lived. We talk about this in more detail in “How Long Do Car Batteries Last UK”.

How does car battery health affects how long your battery lasts without driving?

Have you ever wondered why sometimes a person can have a long-term relationship with their battery, lasting 7-8 years and sometimes even a full decade; and other times it packs up after a bare couple of years?

Well, luck definitely has its role, as it does with any product in the world. No matter how well made a product is, and by how good a manufacturer, there are still issues with the occasional product.

The brand of battery plays its part too. We’ve picked the top battery brands in the UK based on our years of experience with car batteries. Higher quality brands last longer and cope better with mistreatment.

But we’ve come to realise the major necessity for a long battery life, the main ingredient of the stew, if you will, is how the battery is treated. Other car battery maintenance tips are the additional ingredients that improve the flavour (if you’ll excuse the tortured metaphor.

What does it mean to treat the battery well?

Basically, it’s to keep it fully charged as much as possible. That’s what lead-acid car batteries need. Other lead-acid batteries, such as deep cycle batteries, used by campervans, caravans and suchlike, are okay with deep discharge – being discharged down to around 50%.

But lead-acid car batteries should be kept with as close to a full charge as possible, as often as possible. So the best way to keep your battery healthy is to use if often, and on long journeys – that way it gets a full charge. If you only use your car for short journeys, it may not be getting the full charge that it needs.

When a lead-acid car battery doesn’t get a full charge, it suffers from sulfation, and that shortens a battery’s lifespan.

Battery sulfation is the build-up of lead sulfate on the battery plates. This is a byproduct of how lead-acid batteries work, it’s natural chemical process. But when the battery doesn’t get a full charge, these lead sulfate crystals harden and compact together. A battery can store charge because of a chemical reaction between the lead plates and the electrolyte. When crystals form and harden on the lead plates, they lessen the quantity of these chemical reactions taking place. Therefore, they inhibit the battery’s ability to store charge and deliver power. Until eventually the crystals completely block the power. At this point, the battery is effectively dead.

When you fully charge the battery, (most of) these sulfate crystals are turned back into liquid and join the battery electrolyte from whence they came.

If my battery health is poor, how long will the battery last if I don’t use it?

If you don’t keep your battery fully charged often, it is likely that it has some sulfation on the battery plates. That means your battery is not in the best condition.

So if you go away and leave it unused for even 2 weeks, it may be that the sulfate crystals become more hardened and stuck to the battery plates than before and the battery won’t start for you.

Here’s how to see what battery voltages correspond to what battery charge % levels – Car Battery Voltage Chart UK.

Not using your car battery, then, is like a race between you and the sulfate crystals. Can you charge the battery before the crystals have hardened so much that it blocks the power delivery of the battery? That’s the question.

What about if my battery health is good?

If you normally regularly give the battery a full charge, and the battery is relatively young, then you’ve bought yourself more time.

There is likely to be relatively little sulfation on the battery plates. So it will take more time for the sulfate crystals to develop and grow. In this case, you may have as much as 6-8 weeks before the battery power is completely blocked by the sulfate crystals. If you start the engine and get a full charge, you’ll be able to remove a lot of the crystals as part of the charging process.

What other factors can affect how long my battery lasts?

Here are the main other factors.

Parasitic Drain

This is when your car’s electrical system continues to draw electricity from the car battery, even when the vehicle is shut off.

Some causes of parasitic drain:

• Headlights
• Glove compartment lights
• Computer module
• Radio
• Clock
• Alarm
• Power mirrors

Essentially, it’s any electrical item that continues to draw power from the battery even when they’re off.

It’s different than leaving lights on overnight, for example – that’s just human error and a mistake you just have to try to avoid.

A small amount of drain from the battery (with the vehicle shut off) is acceptable. If it’s low, it won’t have too much affect on how long your battery lasts when you don’t drive the car.

But if parasitic drain is too high, it can certainly shorten the amount of time your battery will last.

That’s because the lower the amount of charge in the battery when you come to restart it, the less power it has to perform the start.

How to maximise how long my battery lasts without driving?

There are a few simple actions you can take to maximise the length of time the battery lasts without being used.

1) Give the engine a run

if you’re not driving your car for an extended period of time, start the car and run the engine for 10-15 minutes (ideally take it for a drive) once every couple of weeks

If it’s because you’re going to be away on holiday, it could be worth getting a friend to do this for you.

If I’m on holiday for only a couple of weeks do I need to do this?

If your car battery is in good condition (you’ll know this from our discussion about battery health earlier in this article – do you fully charge it regularly?) and it’s not too old, we’d advise that if you’re only away for 2 weeks, that you don’t need to get someone to start the car and run the engine.

If your battery could be in poor condition, or is getting on a bit, it would be good to get a friend to run the engine as described above after a week or so.

As for idling, that is, running the engine but not actually driving the car? Well, here’s Does A Car Battery Charge While Idling?.

2) Use a smart charger

If you’re not driving the car for a while, instead of taking it for a drive/running the engine as per the advice above, you can just connect it to a battery charger for a day or two. That’ll give the battery a full charge – and remember, a full charge is what a lead-acid car battery needs to stay healthy and powerful.

The more often it gets a full charge, the less chance sulfation has to take root (by which we mean the sulfate crystals hardening and sticking more strongly to the battery’s lead plates), and the battery retains more of its ability to take on charge and deliver power to the car.

Any car battery charger is good, but with a regular charger you may need to monitor it to make sure it doesn’t get overcharged.

With a top smart charger (like the CTEK MXS10 charger), though, you can set and forget. It’ll give the battery the exact type of charge needed for its current state of charge. You can leave it connected and even when it reaches full charge, it’ll monitor it, and then top up the charge whenever it drops, as needed.

If you’re away on holiday, you may even be able to leave a smart charger connected while you’re away – but check with the manufacturer if this is advisable, and do so at your own risk.

Here are the best smart battery chargers in the UK.

3) Use a desulfator

Any battery loses charge over time. And if it loses charge it loses power and therefore has less ability to successfully start your car.

That said, it’s sulfation that weakens the power of the battery in a more permanent and damaging way.

But sulfation is reversible. The best smart chargers have a desulfation mode as one of their functions (we’ve reviewed them and found CTEK Recond Mode is the best for reconditioning car batteries). This mode puts a high-frequency pulse across the battery plates, which breaks down more of the lead sulfate crystals than ordinary charging modes are able to. The lead sulfate is then able to be a part of chemical reactions again. And this means more charge can be stored, and the battery can thus give out more power. Which means better starting ability.

And there’s an even better battery sulfation method. That’s a device that largely prevents sulfation from happening in the first place. It’s called a desulfator. It stays permanently attached to your car battery; and it is always sending high-frequency pulses to stop the sulfate crystals forming and removing any crystals that have already formed.

How does a desulfator help a car battery last longer without driving?

Using a desulfator means the battery has less sulfate on the battery plates. And therefore it will retain its power for longer when it’s not being used.

For example, battery that would otherwise have stopped working after 2 weeks not being used, may least for a month or even more.

The best desulfators (like the F16 Pulse King) only acts when the battery voltage is sufficiently high, when the car’s engine is on. So it won’t drain the battery when you’re not using the car.

Does that mean if you’re not using the car that sulfation will develop, even if you have a desulfator? Yes, it does. But the point is that the battery is in far better condition to begin with (since the desulfator has been operating every time you’ve used the car). And so your battery is starting from a place of good health – so it can cope better with those periods of not being used.

4) Avoid/prevent parasitic drain

Here’s how to check for parasitic draw.

In brief, you get a digital multimeter (or better yet, a 12V car battery tester). Turn the engine off and check the current level. If it’s higher than around 80mA, you have a potential electrical problem, and should take it to a professionally qualified mechanic.

Need to interpret the voltage measurements? Here’s a car battery voltage chart.

There could be an issue that affects the circuits that power your car’s accessories. The mechanic should be able to isolate and identify the issue, and then fix it for you.

These 4 methods not only lengthen the amount of time a battery can go without driving, they also maximise the lifespan of a battery. Given car battery replacement costs in the UK, it’s well worth doing.

How to identify if I need a new battery?

Here’s how you know when your car battery needs replaced. And here’s how to know what car battery you need.

Any other solutions for low battery power?

Keep a jump starter in your car, the latest are lightweight, small, yet a quality one can be highly powerful. Like the Topdon Jump Surge 3000.

How Long Does A Car Battery Last Without Driving Summary

There you go, then.

That’s how long does a car battery last without driving… answered!

As you read, it’s affected mainly by the current state of health of your battery. You can get a good idea about this by considering whether you give it the treatment it needs to stay healthy – does it get a full charge very often?

If it does, and it’s not too old, it’s likely to last at least one month and perhaps even two without driving.

If you go on a lot of short journeys and the battery isn’t getting fully charged too often, and if it’s getting on a bit, then it may only last a week or two.

Here’s the key point to take away from the article – if you go even a week or two without charging the battery, you’re damaging it!

Lead-acid car batteries need regular charging, to full 100% charge, as often as possible. Doing this is what prevents sulfation taking hold of your battery.

Lack of regular charge basically allows sulfate crystals to take hold, harden, stick more tightly, and thus suffocate the lead plates. This blocks the battery’s ability to deliver power to the car. Less power means less chance of the battery starting.

If the battery has reached the end of its useful life, here’s all you need to know about car battery disposal.

Hopefully, this sheds some new light for you on what car batteries want, and how you can keep them lasting longer when you’re not using them.