On Battery Life

While the march of progress in technology has been swift and exponential, the one area that seems to lag behind the most is battery life. It has remained fairly consistent over the past few decades, with little “revolutionary” advances being made. There have been improvements of course, but nothing like the Moore’s Law increases we see in memory and processing power. While Apple has always placed battery life fairly high on its list of priorities, it’s faced the same road blocks as every other tech company in increasing battery life in its portable devices over the years.


Looking at the graph of the evolution of Apple’s battery life in its laptops, you can see Apple started off with a bang, having the original Mac Portable computer run with a stellar 12 hours of potential battery life. Yet, that was the result of them shoving in a two pound lead-acid battery, the same type used in cars. Apple quickly realized giant lead-acid batteries would not be feasible in future products and transitioned into more modest NiMH and Li-ion based batteries and entered a long lull in battery technology. For around two decades, Apple laptops had battery lives only averaging around 5 hours. Some were on the lower side and a few higher, but it wasn’t until the last few years that Apple has been able to reach into the double digits of battery life.

In 2010, Apple managed to touch the magical 10 hour battery life for two of its products – the final version of the plastic MacBook and the 13-inch MacBook Pro. For the MacBook Pro, the increase was the result of Apple having transitioned the MacBook Pro line to non-removable batteries and its use of new software technology. However, a year later the MacBook was discontinued and the MacBook Pro was refreshed, reducing its battery life back to 7 hours. It wasn’t until this summer that Apple managed to again reach double digits in terms of battery life in one of its laptops, with the current 13-inch MacBook Air getting an estimated 12 hours. So a mere 22 years after the Mac Portable, Apple has again managed to make a portable computer that has 12 hours of battery life.1


In addition to Apple’s laptops, battery life is a very important part of their iOS devices such as the iPhone and iPad. However, both have been fairly stagnant in terms of advances in battery life over their lifetimes.

The graph above unquestionable illustrates the utter lack of increase (or decrease) in the iPad’s battery life – with every single model, including the Mini, having the exact same 10-hour battery life.

The graph for the iPhone shows there has seen some increase in the past six years, although nothing terribly revolutionary. The original iPhone had only six hours internet browsing over wifi, which has slowly increased over subsequent generations to reach the 10 hours on the current iPhone models. Talk time has also slowly increased to match web browsing with an estimated 10 hours.2


It seems Apple believes 10 hours is currently the magical number in terms of battery life, with all of their devices hovering around that number. It’s interesting that given the dramatic size differences between devices, that the battery life remains fairly close. You’d think the larger devices would have proportionate increases in battery life, since you can fit in larger batteries. However, the larger devices have more power hungry features that eat up the extra battery, such as the large, retina screens in the iPads and the Intel processors and full fledged OS in the MacBooks.

While 10 hours is more than twice the average battery life than previous Apple portables from the past two decades, it still seems rather weak in comparison to other technological advances. Compare the specs of a PowerBook 2400c from 1998 and a MacBook Pro from 2013. The MacBook Pro has a processor that is at least 20 times faster, has over 200 times the amount of storage, and has 500 times the amount of RAM. Yet, despite being exponentially superior in almost every way, the MacBook Pro’s battery life is only a measly two hours more than the PowerBook’s battery. How can all the other technology increase so astronomically, yet battery life basically stand still?

A big part of the reason is battery tech is still rather crude, with batteries being made merely out of mixtures of chemicals such as nickel and lithium. This basic concept of a chemical-based battery hasn’t fundamentally changed for over two hundred years. While batteries have gotten more efficient to some degree, most increases in battery life in the last twenty years are the result of software working more efficiently to make better use of the available battery. But there is a limit to how much you can squeeze out of these small packages of chemicals. Portable devices are only getting more powerful and feature filled, so something will have to give to even retain the current levels of battery life.

With how important these portable devices are becoming in our lives, I think a revolution has to be on the horizon. Some new tech that will blow away chemicals and give exponential increases in battery life. There are candidates out there, such as a silicon supercapacitor, but these are still in the experimental stages. In the meantime, it remains rather disappointing that I can barely get a full days use out of my iPhone, and not even that if I use it more heavily. I hope future generations will laugh at how terrible battery life used to be, and devices will eventually get days, if not weeks of power without having to be charged. Right now, however, that is still a ways in the future.

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1. Later Apple Newtons did get fairly crazy battery life, with the MessagePad 2100 getting an estimated 12-36 hours of continuous use, and 2-3 months of “average” use. However, its hard to compare the very limited Newtons to laptop computers or even iOS devices.

2. This is caluclated using 3G talk time, except for the original iPhone which lacked any 3G capability.

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