There is an important debate going on in the great halls of our society. Well, let me put some perspective on that. A bunch of people on Twitter get really excited about this stuff, but it does not make the topic any less important. I am talking here about removable back covers and swappable batteries. Now lets be clear, this is going to be a discussion about what you can fit inside any given volume of space and not about the space itself. I am not making the argument that a fixed back phone should be thinner than a removable back phone and anyway, the Samsung Galaxy S4 and its removable back would disagree - it is one of the thinner phones of 2013.
There was a time when all phones were the same in this regard. You could take the back off, change the battery and in the process could type on a proper keyboard be it just the number pad or a proper QWERTY unit. Back in the mid 2000's, the technology inside mobile phones was advanced for the time but fairly primitive by todays standards and as such, the volume available for a battery was limited. SIM cards were full sized and electronics were relatively large.
And then the iPhone happened. Well, that might be a simplistic but a trend was set from there for devices to have sealed backs and therefore non-removable batteries. This presented a major challenge at first as battery technology was relatively basic and the components used to make mobile phones were relatively power hungry. As time has gone on, there has been a reasonable level of balance between the density of power in batteries and the power consumption of the various parts of phones.
One of the primary drivers behind the additional longevity experienced on high-end phones today is the additional space inside our large devices that can be packed full of battery. Whilst power consumption of screens goes up broadly in proportion their size, the batteries also grow proportionally. The remainder of the battery using components will draw the same power no matter the size of the phone. This is proven out by the exceptionally long call times that can be achieved by devices with big batteries, while the screen on time remains similar between devices of all sizes within the same market segment.
Today, there are fewer and fewer phones with removable backs, especially amongst high end flagship devices. I would posit that two things are at play here. First, batteries have now become large enough while phones are also efficient enough to last the majority of people through one full day. It seems generally accepted that a phone lasting a full day is good enough. Secondly, it is easier to make a nicely designed, space efficient, solid feeling phone without having a removable back.
When a phone is being designed, manufacturers are looking to fit the largest battery in terms of physical volume that they can into the device. The mechanism for a removable back cover takes space within the body thereby affecting the remainder of the available volume. I would present the LG G2 and the LG G Pro 2 as case studies here. The LG G2 has a 5.2" screen and a 3000mAh battery. The G Pro 2 has a 5.9" screen and a 3200mAh battery.
The LG G Pro 2 is approximately 14% taller, 15% wider and 6% thinner than the G2 but weighs around 20% more. Despite this much larger body, its battery is less than 7% larger. The chipset, radios, SIM card slot etc etc take up no extra space in the larger phone and while some of the loss of battery capacity growth can be described by the presence of the SD Card slot, in general I would suggest that having a removable back and a removable battery has affected the battery size.
The G2 has a stacked battery, that is one where different sized batteries are stacked on top of each other to make best use of the curved shape of the G2. Despite having a similarly curved back, the G Pro 2 does not have this and that is in part due to its removable nature. Is a removable battery a benefit on a device like the G Pro 2?
Whilst I have only cited one example and the Samsung Galaxy S4 certainly could be used to disprove my case here, I believe it to be an interesting thought experiment to wonder how close to 4000mAh the G Pro 2 battery could have got with more efficient use of the available volume.
Indeed, the stacked battery is the key here. If you have a curved back such as the new HTC One M8 but not stacked battery, then the available space for battery becomes quite limited and this is demonstrated with the M8 only have a 2600mAh battery in quite a large body. Perhaps this debate should be to stack or not to stack!! So what about the alternative to a stacked battery?
Consider phones such as the iPhone and the Sony Xperia Z range. These are very square and flat devices which maximise the volume in the phone for a given set of dimensions. And when you consider those dimensions, the batteries that these phones include are very large. How would either Apple or Sony manage if they made the battery removable? Would they feel as solid in the hand and would they have such large batteries? Keeping the device so square means they don't have to use complex and expensive technologies such as stacked batteries.
My opinion is that I would prefer my phone to have a sealed back with the largest possible battery that can be fitted in the available volume and enough internal storage to negate the need for expansion - 32Gb does it for me personally. That way I believe I get the best overall battery life without compromise.
What is your opinion? Please let me know in the comments below. Have you ever swapped out your battery and is that better than using a small external battery booster?