This past week, I have had multiple people ask me about dealing with laptop batteries that are either dead or no longer last more than a few minutes. Throughout all the years I have helped Mac users, nothing has frustrated users more than batteries dying after six months, 18 months, or anytime that the user still owns his or her laptop. Why is this the case? I could say that users do not have a good understanding of how batteries work. I could say that computer companies do a poor job explaining the lifespan of a battery, or worse, lie about it. But the hard truth is that we, as laptop users, demand the impossible: a battery that never dies and never loses capacity.
In this article, I want to explain a very small amount of battery technology, provide a few tips on maximizing your battery life, and give advice on determining whether a battery has naturally died or is defective.
Today, all major computer manufacturers use Lithium Ion batteries. Lithium, as a metal, is lighter than the older battery technology: nickel cadmium and nickel metal-hydride. If you use rechargeable batteries in your home appliances in common sizes like AA, AAA, C, D, or 9-volt, those are still nickel metal-hydride batteries.
Because lithium is lighter than nickel, you can literally pack more of it into the same space, and the battery will be lighter. That’s great for the laptop user on the go, but it’s also more expensive: a new battery from Apple costs $129 (except for the 17″ MacBook Pro). Lest you think that’s expensive for a computer battery, a quick check at Dell’s website reveals batteries from $125-$300. At HP, equivalent batteries are $125-$150. You can get less expensive 3rd party batteries, which I’ll talk about in a minute, but for now, I want to emphasize that the prevailing technology is Lithium Ion, and that computer manufacturers tend to charge the same amount for batteries.
The Life of a Battery
Batteries have a different life from other computer components. My father purchased a Mac 512k in 1986, and it still runs flawlessly today. That means the logic board, screen, speakers, cables, and everything else inside the computer is still functioning. Sometimes, components fail much earlier. Fail is the keyword. They work one day, and they don’t work the next. While batteries can fail like any other component, all batteries can be completely consumed, meaning their capacity can be used up. The hard truth sentence for this reads: Every time you use your battery, you’re bringing it closer to its death.
How can this be? The metal inside your battery needs to be charged, and when I say “charged,” I mean that the metal literally needs to be given a positive or negative ion charge (if you can think back to your high school chemistry class). Over time, less and less of the metal can continue to be charged, and eventually, your battery cannot be charged enough to power your machine.
You might then ask: ok, so how many times can I charge my battery before it dies? Well, and I’m sorry I have to say this, but it depends. Most lithium ion batteries have a maximum life span of 500 “cycles.” That means your battery probably won’t last more than 500 cycles, and it could definitely last less.
For batteries, a “cycle” is basically a full battery charge. With the older nickel batteries, computer manufacturers recommended that consumers not charge the battery until it became completed empty. That way, you’d get the most out of your cycle: charge the battery to 100%, use 100% of the battery, and start over. With the newer lithium ion batteries, this is no longer true. You can charge the battery whenever you want, and you will not prematurely kill your battery. This is good news. If you start using your battery at 100%, let it drop to 50%, then plug it back in, you’ll only use up half a cycle when it fully charges.
But let’s think about this more closely: if you use your laptop every time, and you use a fully battery cycle every day (meaning, during part of the day, you’re running on your battery and use its full capacity), your battery is probably not going to last more than a year and a half. You’ve got no more than 500 cycles and 365 days in the year.
What’s worse is that each time you use a battery cycle, the battery’s capacity slightly diminishes. Over time, that means your battery won’t last as many hours on a full cycle, even though it charges to 100%.
Maximizing Your Battery’s Life
Just like everything we love, we want to be with our batteries forever (mostly because we don’t want to shell out money for a new one). There are a few things you can do to prolong your battery’s life, but if you’re a true road warrior, they probably won’t be much help:
- Don’t use your battery! This has to be #1. If you’ve read the article this far, you know that to use your battery is to kill your battery.
- How do you avoid using your battery? If you use your laptop at home or at work, it should be plugged in 100% of the time it can be. I know that if you’re sitting at your desk or on your couch, it’s nice not to have a cord hanging off the end of the laptop, but you’re using up your battery’s life for your slight convenience.
- Hopefully, you’ve learned that computer software that taxes the processor (like games and video/audio/photo editing) as well as software that requires parts to move (like watching a DVD) chews up battery power faster than word processing or other, basic tasks. Ideally, if you need to use your battery, try to do the work that requires the least use of the processor while on battery and then plug the laptop in when you have to do the processor-intensive tasks. In this way, you’ll use less of your battery’s current cycle, prolonging its life.
- Do anything else you can to prolong your battery’s cycle. This will not only prolong the overall life of the battery but also the amount of time you can run on the current cycle. For example, you could turn your brightness all the way down. You could spin down hard drives when not in use (see the Energy Saver System Preference). You could avoid plugging anything into the laptop while using the battery.
- Finally, and this one should not be overlooked: avoid exposing your laptop to excessively high or low temperatures. Apple recommends you keep the laptop between 35º-95º F (~2º-35º C). Exposing the laptop to higher temperatures can permanently damage the laptop, including the battery. Exposing the laptop to lower temperatures can temporarily damage the laptop, but it will recover when it warms up. What does this mean? Don’t keep your laptop in your freezing or boiling car!
- If your laptop was kept in your 20º F car, you’ll probably find that your battery won’t last as long the next time you use it. That’s a wasted cycle. But if you had let your laptop warm up to at least 35º F before you turned it on, the battery cycle would have lasted its normal time. It’s like warming up your car on a cold winter’s day.
Replacing a Bad Battery
I hope, at this point, you can understand that if you’ve been using your laptop nearly every day for two years and the battery now only holds a charge for 20 minutes or can’t charge at all, it’s depleted — not defective. Your battery wasn’t supposed to last longer, and you need to replace it if you want a battery that lasts longer.
If you bought a battery three months ago and it only lasts 45 minutes on a charge, that’s a different story. Unless you’ve been going through a full charge 15 times/day (which is impossible), your battery is not depleted due to use. You should consider having an Apple Store or service center test it. In your case, there is probably a defective charging component inside the battery, preventing it from holding a longer charge (rather than simply being “used up” by repeated charging).
What happens when your battery is somewhere in between? Is it consumed or defective? This is the last hard truth: there’s no easy answer. Dealing with underperforming batteries will be a difficult experience for the foreseeable future.
Do you disagree with my explanation of battery life cycles? Have you found better ways to conserve your battery? Have any tips on getting your battery replaced under warranty? Let everyone know in the comments.
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