When working on a mobile device’s industrial design, one of the most critical decisions one has to make is how to package the battery. Do you make it user-replaceable or not? Do you encase the battery’s cells into a rigid plastic package? Do you require the use of a screwdriver to replace the battery? These are the types of questions that have to be answered, and here is our take on them for the Redux Model 1.

One of the major complaints about Apple’s iPod and iPhone is that users cannot replace the battery themselves. According to Apple, a properly maintained iPhone battery is designed to retain up to 80% of its original capacity at 400 full charge and discharge cycles. What this means is that the iPhone will have to be serviced by Apple for the original battery to be replaced within about two years after purchase. This service is offered by Apple for $79, plus $6.95 shipping.

There is a very simple reason why batteries used for the iPod or iPhone cannot be replaced by users themselves: thickness. For a battery to be easily user replaceable, its cells must be encased into some kind of plastic package, making the battery a standalone unit that can be manipulated safely by users. Problem is, such plastic encasing adds thickness to the overall device, and the longer and wider the battery, the thicker the surrounding package has to be in order to make the battery unit rigid enough. When every micron counts, you have no other option than making the battery as thin as possible, and that means fusing it into the device.

Another problem with user replaceable batteries is that you need to give a way for users to easily get access to them. When the battery needs to be swapped on a regular basis (think mobile phone or laptop computer), you do that through some kind of trap door, which locking mechanism adds thickness and bulk. But when the battery needs only to be replaced when it won’t support a full charge and discharge cycle, you can use a more streamlined industrial design that will require the use of some tool to get the battery replaced. This is the option we will adopt for the Redux Model 1.

Less is more, and the less things mobile workers have to carry around, the better, batteries included. Therefore, the Redux Model 1 won’t allow its battery to be swapped on a daily basis, but will allow for it to be replaced by owners when needed. This will require the use of some tool (most likely a standard Phillips screwdriver), and the battery might not be encased into a rigid plastic package in order to cap the device’s thickness to our previously stated goal of 1/2". Nevertheless, an average user should be able to perform this operation solo, following a simple set of instructions.

Instead of carrying an extra battery, users will carry our optional keyboard, which will come loaded with a secondary battery. Whenever the Mini Tablet will be docked onto the keyboard, it will draw power from the keyboard’s embedded battery. This optional accessory still need a lot more work, but we already know that its battery will offer at least as much capacity as the one built into the Mini Tablet. Ideally, it will offer at least twice as much. And for people who really want to carry some extra batteries, we might be creative with the standard iPod/iPhone dock that could be built into the Redux Keyboard Large (Cf. past article).

The idea is actually pretty simple: the Redux Keyboard Large will be 11" x 5.5", while the Mini Tablet is 8.5" x 5.5", leaving 2.5" of extra space that could be used to dock an iPod Touch or iPhone next to the Mini Tablet. With such an arrangement, one could design a spare battery that would have the size of an iPhone, and dock it onto the Redux Keyboard Large in order to power (or even charge) the Mini Tablet. Funky, but totally doable, all without compromising the Mini Tablet’s pure industrial design.