You've probably noticed that with many of our portable devices, especially phones and tablets, a large fraction of the size and weight are the battery. Battery technology keeps improving, and costs go down, and there are dreams of fancy new chemistries and even ultracapacitors, but this has become a dominant issue.

Every device seems to have a different battery. Industrial designers work very hard on the design of their devices, and they don't want to be constrained by having to standardize the battery space. In many devices, they are even giving up the replaceable battery in the interests of good design. The existing standard battery sizes, such as the AA, AAA and even the AAAA and other less common sizes are just not suitable for a lot of our devices, and while cylindrical form factors make the most sense for many cell designs they don't fit well in the design of small devices.

So what's holding back a new generation of standardization in batteries? Is it the factors named above, the fact that tech is changing rapidly, or something else?

I would propose a small, thin modular battery that I would call the EStick, for energy stick. The smaller EStick sizes would be thin enough for cell phones. The goal would be to have more than one b-stick, or at least more than one battery in a typical device. Because of the packaging and connections, that would mean a modest reduction in battery capacity -- normally a horrible idea -- but some of the advantages might make it worth it.

Quick swap

There are several reasons to have multiple sticks or batteries in a device. In particular, you want the ability to quickly and easily swap at least one stick while the device is still operating, though it might switch to a lower power mode during the swap. The stick slot would have a spring loaded snap, as is common in many devices like cameras, though there may be desire for a door in addition.

Swapping presents the issue that not all the cells are at the same charge level and voltage. This is generally a bad thing, but modern voltage control electronics has reached the level where this should be possible with smaller and smaller electronics. It is possible with some devices to simply use one stick at a time, as long as that provides enough current. This uses up the battery lifetime faster, and means less capacity, but is simpler.

The quick hot swap offers the potential for indefinite battery life. In particular, it means that very small devices, such as wearable computers (watches, glasses and the like) could run a long time. They might run only 3-4 hours on a single stick, but a user could keep a supply of sticks in a pocket or bag to get arbitrary lifetime. Tiny devices that nobody would ever use because "that would only last 2 hours" could become practical.

While 2 or more sticks would be best for swap, a single stick and an internal battery or capacitor, combined with a sleep mode that can survive for 20-30 seconds without a battery could be OK.

Public infrastructure

With standardization, an infrastructure would grow up around ESticks. You would be able to buy new ESticks anywhere, like corner shops, possibly even disposable the way alkaline AAA batteries are. You might also find multi-stick EStick fast-chargers in all sorts of places -- hotels, conference facilities, waiting areas, transit, etc. Indeed, you might not even recharge your batteries in your device if it's really easy to charge the ESticks. Particularly if it's very fast -- the public chargers might be designed with cooling and high current.

There is also the potential for trade. ESticks would have chips in them, and if these can be trusted to accurately report the age of other attributes of the battery, one could have a system where stores give you a full EStick for your empty one, adjusting for the age of the stick given. (Admittedly this might give rise to fraudulent sticks.) Vending machines could handle the process.

As noted the sticks would have chips in them, which would handle not just charge counting and age and identification (some privacy issues here) but negotiation on power in smarter sticks. A popular "stick" would be one that is actually an AC adapter, particularly for devices like cameras that don't have external power inputs.

On many devices, the stick port might even be (if it doesn't need a door covering it) a suitable docking port with enough size to physically hold the device as well as power it and communicate data. Yes, the EStick port should have some wires able to do high speed data just for this.

Security

All of this has security and privacy issues. One useful feature would be the ability to give a stick a digital key. If you put a stick into a public charger (that declared itself as public,) the stick would then go into a mode where it can only go back into a device it's been in before. As a result, casual theft of sticks from public chargers would be fruitless.

If there's a data connection in the stick, again we must be on the lookout for malicious ESticks and assure they can't now fake out or take over our devices. The use of an encrypted tunnel could ensure that only your own dock can say it's a dock.

Market

Sticks would not be expensive. On the other hand, for some that's a bug, not a feature, as many device vendors like that their devices take only proprietary batteries and that you must buy them, at high cost, from the original vendor. With the EStick approach, devices would eventually not even come with ESticks or chargers, expecting you to already have them or get them elsewhere.

Sizes

While we would want to keep the sizes to a minimum, there would still be some variations in size needed. You don't want all sticks to be able to power a watch or eyeglass, and you don't want to have to put 10 sticks into a phone or 50 into a laptop. Sticks could be designed so it's possible to combine multiple sticks in a holder of one of the larger sizes. Chargers could also be designed with adjustable slots to take all sizes of stick. A typical charger should take multiple sticks and people would have several to charge each night. Devices that must run at night (like phones) would continue to need external power such as micro-USB.

Some devices might elect to have their own internal battery and have just one stick slot. In this case, the internal battery would never be drained so much that you can't hot-swap -- and indeed the stick might use some of its power to restore charge into a drained internal battery for the next hot-swap.

Not all devices need hot-swap. Still cameras and other fast-boot devices without a lot of state are fine with cold-swap. Slow-boot devices like tablets and phones prefer hot-swap or warm-swap. Devices like video cameras which want to shoot continuously need hot swap.

When ultracapacitors arrivek, an EStick approach could be great. Aside from letting all the old devices use the new sticks, fast-charging an ultracap needs a high-power connection which the device itself may not have. However, a charger with access to the whole stick and special charging electrodes could charge it in seconds. A person with two such sticks could swap them, run for however many hours they provide and recharge the stick that's out whenever a fast-charge station is encountered.

So, how many form factors would we need? We can't do worse than now. We have 5 different kinds of Canon camera we sometimes carry, for example, and they have 4 different batteries and chargers. (There are some chargers that offer multiple charging plates but none with all of them as yet.)

In addition, vendors would also make EStick based units which have a micro-USB or other charging connector on them, to mount your phone or other device in to power and charge it, even if it does not have internal sticks. People already sell these, but they are proprietary.