How Long Does a Home Battery Last? [CNET]

The average lifespan is about 10 years, but it depends on the battery and how you use it.

Batteries can’t last forever. If you own a smartphone, you’ll notice that the battery’s charge diminishes over time and that you need to plug in your phone more often.

But this issue isn’t exclusive to smartphone batteries. All batteries have a limited lifespan and eventually need to be replaced. Even home batteries, giant lithium-ion batteries that act as a backup power source for your home, are not immune to the inevitable demise their smaller counterparts face. 

“It’s no different than your iPhone battery,” Cameron McDonald, vice president of merchandising, planning and inventory at Batteries Plus, told CNET.

Although a home battery is designed to last longer than your iPhone battery, it’s still not going to last forever. So how long will your home battery last? And what can you do to extend its lifespan? Here’s some expert advice on how to get the most out of your home battery.

How long does a home battery last?

The most common types of home batteries, typically made of some sort of lithium-ion chemistry, degrade over time just like any other battery. Each time you charge and discharge your battery, it loses some of its capacity to hold a charge. It’s so inconsequential that you won’t notice it at first. But after a few years, you might start to notice that your battery can’t hold a charge quite like it used to. 

Your home battery is not going to live forever, but it might last longer than you think. “Anticipate it to last about 15 years,” McDonald said. 

Look closely at the warranty

Almost all home batteries on the market come with a 10-year warranty. However, that doesn’t necessarily mean your battery will be totally dead in 10 years. The thing you really want to pay attention to on your battery’s warranty is its cycle life or expected energy throughput. Both of these give you a good indicator of how long your battery will really last, according to the manufacturer. 

Every time you drain and recharge your battery it completes a “cycle.” On your warranty, the manufacturer guarantees your battery will be able to deliver up to a certain amount of cycles while under warranty. The expected life for home batteries is usually between 6,000 to 8,000 cycles. 

Similarly, you might see an expected energy “throughput” listed somewhere on your warranty. This is another way the manufacturer estimates your battery’s lifespan. Your battery’s throughput, usually measured in megawatt-hours, is the total amount of energy that your battery should deliver to your home during its lifetime while still under warranty. 

Since your battery’s maximum energy storage capacity decreases over time, most manufacturers will also include some form of end-of warranty capacity guarantee, promising that your battery will still be able to retain up to a certain amount of its original maximum capacity by the time your warranty expires. Most manufacturers will guarantee up to at least a 70% capacity retention rate. You can still use your battery after your warranty period is up — possibly for another five years, even. Just don’t expect the battery’s performance to be as good as it was when you first had it installed.

Factors that can affect your home battery’s lifespan

Not all batteries are created equal — and even batteries that are similar won’t all last the same amount of time. That’s because a number of external factors can affect your battery’s lifespan. Here’s a few things to consider. 

Exposure to extreme temperatures

Sometimes the things that can affect your battery’s lifespan are things that are completely outside of your control, like the weather. If you live in an extremely hot or cold climate, that can shorten your battery’s lifespan, McDonald said. When you’re thinking about where to put your battery, try to keep it somewhere that reduces its exposure to temperature extremes. 

If you live in a hot climate, keeping it indoors, or at least somewhere shaded, can help your battery last longer. If you live in a cold climate, keeping it insulated from the elements will also help. If your home has a garage, consider having it installed there.

Depth of discharge

The way you use your battery can also affect its lifespan. A battery’s depth of discharge refers to the amount of energy you can safely drain relative to its maximum capacity. If you drain your battery all the way to zero before you recharge, that can actually hurt your battery, McDonald said. Many battery systems won’t even let you discharge that far for this precise reason, as a way of protecting battery health.

Number of charging cycles

Battery lifespans of 10 or 15 years assume that you’ll run a certain number of charging cycles. Each time you drain and recharge your battery, it reduces the lifespan a little bit, according to McDonald. 

So if you end up cycling your battery more than what’s recommended by the manufacturer, you might end up with a lower-than-average battery lifespan. “It gives wear and tear,” McDonald said. Check your battery’s warranty to see its expected cycle life.

Physical damage

It probably goes without saying, but you’d be surprised how easy it can be to accidentally damage your battery. McDonald said he’s seen a number of people bump into their battery with their car while pulling into the garage. If you damage your battery like this, it’s probably going to reduce its lifespan. When scoping out a location to install your battery, work with your installer to find a spot that’s both easy to access and has a low risk of accidental damage to the battery.

Is installing a home battery worth it?

Whether a home battery is worth it depends on what kind of return on investment you’re looking for.

“What’s your goal? If your goal is to save money on your energy costs, a home battery may or may not be right for you,” McDonald said.

Home batteries can help you save money if you pair them with solar, or if you can leverage them against time-of-use rates from your utility company. But you still have to overcome the initial upfront cost of the battery in order to start saving money.

Many homeowners install home batteries for a different reason: They’re a backup power source to supply electricity to their home during an outage. In this case, the return on investment might be less about numbers and more about comfort. “There’s the cash [return on investment], and there’s the peace of mind ROI,” McDonald said.

Either way, a qualified installer should be able to help you crunch the numbers of your specific situation and see if the math works out. Make sure to factor in the federal government’s 30% tax credit offered through the Inflation Reduction Act, too. This tax credit allows you to claim up to 30% of the cost of a home battery installation on your taxes.

Home batteries might not be the right decision for everyone. If you can’t stomach the high upfront costs, aren’t worried about potential power outages or can’t take advantage of time-of-use rates, then a home battery might not be worth it.