A Post about Removable Storage, Removable Batteries and Smartphones
by Anand Lal Shimpi & Brian Klug on November 25, 2013 8:40 PM EST- Posted in
- Smartphones
- Mobile
There's been a lot of talk lately about our position on removable storage and removable batteries in smartphones. Most of the discussion has centered around what we've said in podcasts or alluded to in reviews, so we figured it's a good time to have the complete discussion in one central location.
Let's get through the basics first:
All else being equal, removable storage and user replaceable batteries aren't inherently bad things. In fact, they can offer major benefits to end users.
The key phrase however is "all else being equal". This is where the tradeoff comes in. On the battery front, the tradeoff is very similar to what we saw happen in notebooks. The move away from removable batteries allows for better use of internal volume, which in turn increases the size of battery you can include at the same device size. There are potential build quality benefits here as well since the manufacturer doesn't need to deal with building a solid feeling removable door/back of some sort. That's not to say that unibody designs inherently feel better, it's just that they can be. The tradeoff for removable vs. integrated battery is one of battery capacity/battery life on a single charge. Would you rather have a longer lasting battery or a shorter one with the ability the swap out batteries? The bulk of the market seems to prefer the former, which is what we saw in notebooks as well (hence the transition away from removable batteries in notebooks). This isn't to say that some users don't prefer having a removable battery and are fine carrying multiple batteries, it's just that the trend has been away from that and a big part of the trend is set based on usage models observed by the manufacturers. Note that we also don't penalize manufacturers for choosing one way or another in our reviews.
The tradeoffs are simple with an internal battery, the OEM doesn't need to include a rigid support structure on the battery to prevent bending, and doesn't need to replicate complicated battery protection circuitry, and can play with alternative 3D structures (so called stacked batteries) for the battery and mainboard as well. Personally, I'd rather have something that lasts longer on a single charge and makes better use of internal volume as that offers the best form factor/battery life tradeoff (not to mention that I'm unlikely to carry a stack of charged batteries with me). It took a while for this to sink in, but Brian's recommendation to charge opportunistically finally clicked with me. I used to delay charging my smartphone battery until it dropped below a certain level and I absolutely needed to, but plugging in opportunistically is a change I've made lately that really makes a lot of sense to me now.
The argument against removable storage is a similar one. There's the question of where to put the microSD card slot, and if you stick it behind a removable door you do run into the same potential tradeoff vs. build quality and usable volume for things like an integrated battery. I suspect this is why it's so common to see microSD card slots used on devices that also have removable batteries - once you make the tradeoff, it makes sense to exploit it as much as possible.
There's more to discuss when it comes to microSD storage however. First there's the OS integration discussion. Google's official stance on this appears to be that multiple storage volumes that are user managed is confusing to the end user. It's important to note that this is an argument targeted at improving mainstream usage. Here Google (like Apple), is trying to avoid the whole C-drive vs. D-drive confusion that exists within the traditional PC market. In fact, if you pay attention, a lot of the decisions driving these new mobile platforms are motivated by a desire to correct "mistakes" or remove painpoints from the traditional PC user experience. There are of course software workarounds to combining multiple types of storage into a single volume, but you only have to look at the issues with SSD caching on the PC to see what doing so across performance boundaries can do to things. Apple and Google have all officially settled on a single storage device exposed as a single pool of storage, so anything above and beyond that requires 3rd party OEM intervention.
The physical impact as well as the lack of sanctioned OS support are what will keep microSD out of a lot of flagship devices.
In the Android space, OEMs use microSD card slots as a way to differentiate - which is one of the things that makes Android so popular globally, the ability to target across usage models. The NAND inside your smarpthone/tablet and in your microSD card is built similarly, however internal NAND should be higher endurance/more reliable as any unexpected failures here will cause a device RMA, whereas microSD card failure is a much smaller exchange. The key word here is should, as I'm sure there are tradeoffs/cost optimizations made on this front as well.
The performance discussion also can't be ignored. Remember that a single NAND die isn't particularly fast, it's the parallel access of multiple NAND die that gives us good performance. Here you're just going to be space limited in a microSD card. Internal NAND should also be better optimized for random IO performance (that should word again), although we've definitely seen a broad spectrum of implementation in Android smartphones (thankfully it is getting better). The best SoC vendors will actually integrate proper SSD/NAND controllers into their SoCs, which can provide a huge performance/endurance advantage over any external controller. Remember the early days of SSDs on the PC? The controllers that get stuffed into microSD cards, USB sticks, etc... are going to be even worse. If you're relying on microSD cards for storage, try to keep accesses to large block sequentials. Avoid filling the drive with small files and you should be ok.
I fully accept that large file, slow access storage can work on microSD cards. Things like movies or music that are streamed at a constant, and relatively low datarate are about the only things you'll want to stick on these devices (again presuming you have good backups elsewhere).
I feel like a lot of the demand for microSD support stems from the fact that internal storage capacity was viewed as a way to cost optimize the platform as well as drive margins up on upgrades. Until recently, IO performance measurement wasn't much of a thing in mobile. You'd see complaints about display, but OEMs are always looking for areas to save cost - if users aren't going to complain about the quality/size/speed of internal storage, why not sacrifice a bit there and placate by including a microSD card slot? Unfortunately the problem with that solution is the OEM is off the hook for providing the best internal storage option, and you end up with a device that just has mediocre storage across the board.
What we really need to see here are 32/64/128GB configurations, with a rational increase in price between steps. Remember high-end MLC NAND pricing is down below $0.80/GB, even if you assume a healthy margin for the OEM we're talking about ~$50 per 32GB upgrade for high-speed, high-endurance internal NAND. Sacrifice on margin a bit and the pricing can easily be $25 - $35 per 32GB upgrade.
Ultimately this is where the position comes from. MicroSD cards themselves represent a performance/endurance tradeoff, there is potentially a physical tradeoff (nerfing a unibody design, and once you go down that path you can also lose internal volume for battery use) and without Google's support we'll never see them used in flagship Nexus devices. There's nothing inherently wrong with the use of microSD as an external storage option, but by and large that ship has sailed. Manufacturers tend to make design decisions around what they believe will sell, and for many the requirement for removable storage just isn't high up on the list. Similar to our position on removable batteries, devices aren't penalized in our reviews for having/not-having a removable microSD card slot.
Once you start looking at it through the lens of a manufacturer trying to balance build quality, internal volume optimization and the need for external storage, it becomes a simpler decision to ditch the slot. Particularly on mobile devices where some sort of a cloud connection is implied, leveraging the network for mass storage makes sense. This brings up a separate discussion about mobile network operators and usage based billing, but the solution there is operator revolution.
I'm personally more interested in seeing the price of internal storage decrease, and the performance increase. We stand to gain a lot more from advocating that manufacturers move to higher capacities at lower price points and to start taking random IO performance more seriously.
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Impulses - Tuesday, November 26, 2013 - link
Personally I couldn't care less about the snark but it just leads to pointless comment section clutter... No snark = not having the same arguments cluttering the comments sections (at least not nearly as much) and eclipsing other more interesting topics.I do think internal capacity price and options should be featured and talked about much more prominently though. It's usually an afterthought on phone reviews whereas it's typically one of the large concluding points on a laptop review, and I can't think how the two scenarios differ in any way (other than laptops costing 2-3x as much and lasting 3-4x as long).
mmatis - Tuesday, November 26, 2013 - link
If your phone battery is NOT removable, do you care if the FedPigs can turn it on and listen without you knowing?apertotes - Tuesday, November 26, 2013 - link
Anand, you talk about tradeoffs. I agree, that is really the point. Would I trade a removable battery for killer looks? No, I would not. Would I trade a removable battery for water resistance? Yes I would. There are a lot of opportunities that Apple and HTC are missing, but you still give them credit for getting a stunning and beautiful device. But I thought we this blog was about technology, not about fashion. And at the same time, you do not promote those that are trying to let users upgrade their own devices, which is something truly commendable.I do not carry a spare battery with me, but I switched the 2300 battery on my S3 for a 4200 one, and now my phone last a whole heavy usage weekend in a charge. It is not as slim as it was, but I can't for the life of me deplete the battery in a single day, and that is a really great tradeoff.
As for microsd cards, I think you (those in Anandtech, and probably 99% of the tech journalist) have far too easy access to wifi/LTE, or you just have the money to burn on roaming. But most of us can not afford using Spotify abroad, or are unable to connect to Netflix while commuting. And it is very clear that Anantech is positioning itself in the industry side in this matter, but most of your readers are users, not industry moguls.
repoman27 - Tuesday, November 26, 2013 - link
The responses to this piece are mostly appalling. Show of hands here, how many people who believe microSD cards and spare batteries are the solution to the problem have engineering degrees?In a perfect world, even entry level smartphones would currently ship with the fastest available 128GB eMMC solution and a battery that would last 99.9% of users a full day. Unfortunately the laws of physics and economics prevent this from being a reality.
Removable batteries and microSD card slots require interior volume to implement. For a larger device, that trade-off may work out to the consumer's benefit, but in a smaller device probably not. Once device size and battery capacity increase to a certain point, the likelihood of an end user carrying a spare approaches a very small number. There are also very real reasons why Google and Apple are less than enthusiastic about the mixed storage paradigm, and those reasons are not simply "pure greed".
The best solution to the storage situation is for OEMs to offer appropriate levels of storage at reasonable price tiers. Right now, I think most people would be happy if that came in the form of 32, 64 and 128 GB at $50 increments. For larger phones and tablets, it would be nice to see serious OS level support for microSD cards to alleviate some of the drawbacks and allow those who are so inclined to make use of them.
As for batteries, I think everyone would much rather make it through a day on one charge than carry a spare. This is what OEMs should focus on. I seriously wonder about those who argue for carrying spare batteries. First of all, the environmental impact of everyone owning and eventually disposing of two batteries per device is a horrifying prospect. Also, I use my phone CONSTANTLY and the number of times I run out of juice is maybe a few days in a year. I understand that everyone uses their devices differently, but I seriously think this is more of an issue with behavior or perhaps device choice. If you charge while you're sleeping and showering you should be able to make it through the rest of your waking hours with maybe an occasional top up when you're sitting next to an available USB port or power outlet anyway. If you're inconvenienced by charging then either your device sucks, or you're doing it wrong.
Sealed batteries will always be the most efficient use of space. Improvements in battery chemistry are much harder to come by, so the best way to improve the situation is by making devices more power efficient and using the largest battery possible. Sealed batteries are better, but OEMs that go that route should absolutely offer simple and affordable battery replacement programs.
The bottom line is that most people who advocate for microSD card slots do so because they feel OEMs don't offer sufficient storage or reasonable pricing for the higher storage tiers. I find it interesting that saving what amounts to essentially one month's phone bill at the time of purchase is such a big deal. I'd much rather drop $300 extra on a phone with 128 GB of really performant storage and pay $30 less a month to my mobile operator. Of course people tend to be vocal about certain things and totally miss the bigger picture. Sort of like advocating that OEMs use smaller batteries just so those who are incapable of minor behavioral adjustments can swap them out instead of thinking more about their power usage habits in the first place.
tfouto - Tuesday, November 26, 2013 - link
First of all, the environmental impact of everyone owning and eventually disposing of two batteries per device is a horrifying prospect.And the environmental impact of disposable of a phone/laptop every 2-3 years because of bad batteries is what? wonderfull prospect?
repoman27 - Tuesday, November 26, 2013 - link
If the battery has issues, you just replace the battery. If you're not comfortable doing so yourself, get someone else to do it. Sealed batteries are replaceable as long as you have the right tools, parts and know-how. As I said, "Sealed batteries are better, but OEMs that go that route should absolutely offer simple and affordable battery replacement programs." If you could walk into any retailer and have your battery replaced in 10 minutes for $40 or so, I don't think anyone would consider the sealed battery an issue.Furthermore, most of the phones that are disposed of each year are already less than 3 years old. Due to damage, upgrade cycles and whatnot, I believe 18-24 months is the typical lifespan these days.
tfouto - Tuesday, November 26, 2013 - link
Well, except when they charge you 200$ to change the battery as Apple do...repoman27 - Tuesday, November 26, 2013 - link
Apple charges $79 for iPhone battery replacement, $85.95 if shipping is required, and only if the device is no longer under warranty or covered by AppleCare. As I said, the problem is not with the sealed battery, but with the service options the OEMs bother to provide.Encouraging OEMs to use batteries that make less efficient use of space so they can be more easily swapped out by the end user when they fail is not the solution. If anything it's something they will tout as a feature while reducing BOM cost by using a smaller battery that is rated for fewer charge/discharge cycles.
tfouto - Tuesday, November 26, 2013 - link
well it seems a lot when you can buy a new battery for 40$, and for that price i am talking of a good battery, not a cheap one...Lot's of people dont know how to change, or that's possible to change. They just assume, they need to buy a new phone.
Runadumb - Wednesday, November 27, 2013 - link
." If you could walk into any retailer and have your battery replaced in 10 minutes for $40 or so, I don't think anyone would consider the sealed battery an issue."That doesn't help when you have a battery that is nearly empty, which is my issue. I go to festivals at least once a year and take multiple short wkend breaks away too. The ability to just instantly swap out a dead battery for a fully charged one instead of tethering your phone to a battery pack for a few hours is incredibly useful. In fact I find it so useful that right now a phone lacking that simple ability is a non-starter for me. I don't even consider them.
To each their own. I understand many people don't even think about buying a spare battery, I do and I will support that choice while I have the option. Phone thickness, feel and looks rank low in my buying priorities. Function > form.