They're essential to any laptop, and often a hot topic.
If there's one thing most laptop owners will agree on, it's that they'd all like a better battery. Poor battery life is the number one frustration laptop users have to deal with, and no matter how careful you are, the battery life gets worse and worse the more you use a laptop. Eventually, they fail to hold a charge entirely, meaning you have to shell out for a replacement - no small expense, especially when you haven't done anything with the battery that it wasn't designed for.
But why is that? And why, when processors, memory, hard drives and screens get better and better every year, does it seem like battery technology is standing still? We've looked into it, and while we may not be able to improve laptop batteries for you, at least we can explain them.
Li-On Taming
For years, the preferred type of battery for any mobile computing device, be it smartphone, tablet, digital camera or laptop, has been a lithium-ion or li-on battery. The problem manufacturers face is that the basic capabilities of li-on technology hasn't really improved since it reached a viable commercial state in the 1990s. There have been slight refinements in the technology, but broadly speaking the li-on batteries of today are identical to the first ones you could buy.
Unfortunately, they're being asked to power considerably more powerful devices, which see far more use than the ones they originally powered. The problem is that at a physical level, the batteries simply can’t improve. Li-on batteries store the lithium ions using graphite, and there's a hard limit to the amount of ions that can be stored Modern batteries are so efficient that the only way you can improve a battery's capacity is to add more graphite, which makes the battery bigger and heavier, which makes the device bigger and heavier, which makes it more expensive and less attractive to buyers.
Although manufacturers are doing their best to bring down the power requirements of modern systems by shrinking processor dies and creating more economical power-saving firmware modes to be employed when the hardware idles, the simple fact is that li-on technology isn't going to get better.
It's not for lack of trying either. In the past, new batteries were trialled using silicon electrodes, rather than graphite, which has ten times the theoretical capacity. But the silicon swelled when it was charged, which caused minute fractures in the materials, which quickly reduced the overall capacity of the battery. When you consider that mobile devices have to last for years at a time, accepting hundreds of charges, durability is as important as capacity.
Other attempts at improving laptop batteries have been just as doomed. A graphene-silicon hybrid, which combines the stability of graphite with the capacity of silicon has been proven to work, but it's currently impossible to manufacture in commercial quantities due to the scarcity of graphene. Alternative technologies like lithium-sulphur and lithium-air are being trialled for the automotive industry but have yet to come anywhere near computing.
Although battery life is a big issue for laptop owners, it's not just that which bothers the manufacturing industry. Current battery technology can run a modern system for five to eight hours of normal use, but new hardware and protocols draw more power. Suddenly, to keep a system running for five to eight hours, batteries will need to be bigger or more efficient.
Essentially, if you want the laptops of the future to support features like 4K video, wireless mirroring, and next-gen wireless like 4G and wireless AC without a drastic reduction in battery life, manufacturers need to find a way to get better batteries into our laptops. One way or the other, it’s possible. Only in the next few years will we find out whether the solution is bigger batteries or better ones.
Charging More
Finding better technologies is only half of the battle, though, and one that’s largely out of the hands of the consumer. What about the things you can effect, like replacing or upgrading your current battery?
Like all rechargeable batteries, li-on-based cells lose their ability to hold charge as they age. If you've had your laptop for a year or two, you'll no doubt have noticed the drastic decrease in its capabilities compared to when you bought it. Eventually, batteries will cease to hold any usable charge, and it's at this point that you have one option: replace it completely.
Replacing a laptop battery isn't actually difficult. They're designed to be removable, and most don't even require a screwdriver to remove. Much harder is the task of actually selecting a new battery.
It can be difficult to know which battery brands are trustworthy and which are dubious. The list of capabilities and specifications laptop batteries offer can be full of impenetrable numbers and acronyms designed to look impressive but which don't tell you what you want to know about batteries: are they actually any good?
When it comes to choosing a battery, one of the important values to look at is the milliampere-hour or mAh rating. This gives you the capacity of the cells inside the battery, which broadly indicates their quality and size. For reference, an AAA battery is a single 1000mAh cell. A good laptop battery should be at least 5200mAh, while lower-quality generic brands are often 4400mAh.
The difference is that higher-capacity laptop batteries use high-quality cells, as manufactured by big name companies such as Sony, Samsung and LG. Cheaper, lower-quality batteries use cheaper cells with poorer quality control, which makes them more likely to fail -sometimes catastrophically.
A good way to check whether you're buying a good or bad battery is to check the pricing. Good batteries cost toward, if not more than, £100. The least reliable cost as little as £10, but anything under £30 is cheap enough to be highly suspicious. Don't let yourself get taken in by good reviews on sites like Amazon - cheap batteries might perform as normal for the first six months or so, but their performance drops off quickly.
The reason the prices of bad batteries can be set so low is because the manufacturers have very low standards with regards to service lifespan, power capacity and safety performance. Power cells can also degrade even when they aren't being used, so if you see a name-brand battery being sold extra cheap, it might be that you're seeing old, depleted stock being sold at as low a price as possible to recoup some of their cost. Buy a cheap battery, and it might be only weeks away from becoming impractically inefficient.
In essence, if you're trying to replace your laptop battery, be prepared to pay for quality. If you don't think your hardware will last more than a year, you can chance a lower-quality battery, but even then try to stick to the higher end of the price range. If you stay away from low-quality hardware, a battery upgrade can make your laptop feel like new. But buy the cheap stuff, and that's what your laptop will feel like.