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The future of batteries …

May 1st, 2008 · 283 Comments

I’ve noticed something unusual about certain products, the batteries are sealed inside the unit. Sure, consumers hate it when they have to have the unit serviced when the battery gets weak, but manufacturers just keep doing it.

Apple has been doing this for years. The battery is sealed inside of an iPod, and now with their new Air computer, the battery is sealed inside of there as well.

It would be easy enough to just claim that Apple is simply trying to build in a little self-obsolescence, but their products don’t seem to be generally guilty of this. A twelve-year-old iMac works just fine with their new operating system. (Could you imagine trying to run a twelve-year-old PC with the newest copy of Windows?) It seems that Apple actually gets some kind of anti-capitalistic joy out of seeing their old machines still in action. And to be sure, their old machines are still in action, my wife’s yoga studio gets along fine with one of the very first iMac’s ever made as their iTunes player. My friend Rob happily computes on a first-generation iBook.

So why seal the batteries inside of the unit?

I think I’ve figured it out. It seems to be a move to in general do away with all of the old-style ports and connections in general. I suspect that future Macintosh computers will eventually do away with all of the ports, and everything from USB keys to projectors will all work wirelessly, through Bluetooth Adv, 3G or whatever fancy new wireless protocall they will have in the future.

But batteries, what gives on those? Surely even the most futuristic notebook computer will still need a power source. Why seal the thing inside of the unit?

Well, batteries are more durable and longer-lasting than they used to be, but I suspect that the real reason for sealing them inside of the unit is because current manufacturers are expecting something that will allow future batteries to stay permanently sealed inside of the unit without the need for the rare service session to replace the tired cells. But what battery never gets tired? Isn’t the nature of chemical storage that batteries wear out?

Yes. Everytime, and all the time. The laws of thermodynamics guarantee that the process of storing electricity in a chemical matrix and then extracting it again can never be perfectly efficient. No matter what, the process eventually wears down the battery.

But what if our hundred-something-year-old method of chemical-electrical storage were replaced by something wholly solid-state? Not a fantasy, that’s what capacitors do every day, and there are at least as many capacitors in the world as there are microprocessors. But capacitors just don’t have the oomph of batteries, they discharge quickly and can’t hold as much as batteries.

However unlike batteries, capacitors seem quite happy with self-improvement. Just in the last several years, the work by a relatively small number of engineers and scientists has dramatically raised the capacity of capacitors. Advanced dielectrics can now help a capacitor the size of a Cheerio store several Coulombs of charge. (A typical lightning bolt carries about 3 Coulombs of charge, although delivered much more quickly than a tiny capacitor.)

It seems likely that the revolution that benefited microprocessors and data storage is soon going to dramatically benefit capacitors. This is not a bold prediction, but rather something that already happened. Some hybrid vehicles currently use ultracapacitors rather than batteries.

And yes, a capacitor has an inherent limitation that a battery does not, that its output is variable, unlike the steady output of a battery. But this limitation can be regulated and controlled. And unlike batteries, capacitors can be charged and drained for a nearly unlimited number of cycles. Since they store the charge directly, rather than chemically, explosions and fires resulting from defects are less of an issue.

The future of batteries is to be relegated to devices that need long-term storage like flashlights, emergency beacons or starting systems. Batteries will undoubtedly also stick around for cheap toys that can’t justify the expense of a capacitor.

But devices that are recharged regularly, like phones, lawnmowers, electric drills, (like this little fella), and of course notebook computers.

Of course we might not even know when our batteries have been replaced by capacitors since they are sealed inside of the device anyway, right? But you’ll know when you charge up for the day. Instead of taking hours to get a full charge, you’ll only have to wait seconds.

So, invest in capacitors … eventually. One of my favorite capacitor manufacturers is Maxwell Technologies, and as of this writing, full-disclosure urges me to mention that I do not own any stock in Maxwell, however I have owned some in the past, and I might own some again someday.

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