Why you shouldn’t always trust mobile phone battery tests (not even mine!)

Mobile phone battery tests should be objective and easily measurable, right? Well… it’s complicated.

How Do I? covers the basics, because we’ve all got to start somewhere.

I had a YouTube viewer query recently about the results I was getting for mobile phone battery tests, and how they differed not only from what they had seen from other reviewers, but also from the manufacturer’s claims about the phone in question.

They were a touch exasperated, and wondered the following – which I’m lightly paraphrasing:

Why isn’t there one golden battery testing standard for mobile phones to make it all easier to comprehend?

It sounds like a good question, doesn’t it?

It is in a way, though it’s not an easy question to answer.

While the intent is fine, there’s some big challenges to this one that are worth bearing in mind when you’re considering mobile phone battery life.

Are there any international mobile phone battery testing standards?

Yes… sort of.

Or at least as far as my research extends, more than happy to be proven wrong here if someone knows more than I do.

But as an example, ISO 12405-4:2018 is a test for Lithium Ion batteries… but it’s specifically for electric vehicle batteries.

Unless you want to try to shove a Tesla-sized phone in your pockets (somehow), it’s not the right test.

IEC 62133 gets us a lot closer, as it’s a standard for Lithium Ion batteries as used in most smartphones… but it’s actually a safety testing standard, not a battery testing one.

The practical reality here is that most of the technical standards, as far as I can see, relate more to the production and sale of batteries to businesses building tech devices, and not so much how consumers might use them.

What about manufacturer mobile phone battery claims? Are they trustworthy?

You’ve always got to take manufacturer claims with a rather large grain of salt, because they’re almost always heavily qualified in some way.

Let’s use Apple as an example. What does it say about the battery expectations for the Apple iPhone 16 Pro/Pro Max?

Specifications taken from Apple Australia Specifications page

The key qualifier there is the whole business of “up to” timing, because it can do a little or a lot of heavy lifting here.

If I got 26 hours and 59 minutes of battery time, that’s “up to” 27 hours, but then so too is 1 hour and 5 minutes… and I know which battery life figure I’d be happier with!

There’s also something delightfully charming and retro about Apple including audio playback timing as part of its equation.

Sure, people do listen to music on their phones all the time, but does anyone treat their $1799+ smartphone purely as an iPod any more these days? I don’t think so.

It’s the same story too for those brands that list a standby time; a bit of a throwback to the era where all you did with a phone was make and take calls and maybe play a game or two of Snake.

It’s not totally irrelevant of course, few people are on their phones 24/7… but it’s not all that we do with our smartphones these days.

Therein lies the problem with battery testing.

Everyone’s phone usage is different, so how do you measure that?

Some people do just want a phone that is a phone, but perhaps with smart features so they can access, say, government services.

Other people want a phone that documents their digital lives for Instagram or TikTok or similar, forever taking photos and videos of their wonderful existences… allegedly wonderful, that is.

Speaking of which, many folks may use their phones for lots of social media doomscrolling, over and over and over again.

Others may play games, either casual brain idlers, or full-on near AAA titles depending on your gaming preferences.

Or maybe a mix of all of the above and then some.

All of these approaches use up a phone’s battery at quite different rates.

There’s not been a phone developed that I can’t personally send flat within a day if I put my mind to it, though it is more typical to see phones last out a day’s “moderate” usage… but again, that’s an imprecise term.

This is also why even if there was a “standard” phone battery rundown test, it almost certainly would have limitations, because real world usage varies so much.

Test transparency and repeatability are good

I should get on to how I test mobile phone batteries, though if you’ve read any of my phone reviews you’ve probably already hit this paragraph or a variant of it before.

I test with a 1080p YouTube video with the phone set to maximum brightness and moderate (typically mid-range) volume, full screen for a period of three hours from a fully charged battery. For a limited set of typically budget phones that might dip to 720p, but that’s the basic battery rundown test that I do, along with more anecdotal testing as well.

I have only recently started running that test for up to three hours, so some older figures only represent a single hour of testing.

There’s two details I’m looking for here. Firstly, whether a phone drops to below 90% in that first hour. That’s far less common than it used to be, but any phone that can’t get through an hour’s video without depleting its battery by less than 10% is one that I find will almost always struggle to get through a day’s testing. Most of us can recharge our phones daily, so that one day figure is important.

The figures also give me a comparative base to work from. If one flagship phone can manage a 98% figure after that hour and another drops to 92%, then the first phone is likely to have much better battery endurance over the longer term, or be a better match for folks with more battery intensive needs.

That’s just one test. Aren’t the reviewers who do all-day real-life usage tests doing better?

That’s a different approach, and one that I do myself as well in a more anecdotal way… and that’s the precise problem with running only this kind of test.

It’s not that it’s not representing real world use, because of course it is, and those figures do have value of course in evaluating a phone.

The problem is that on a given day, I might use my phone a lot because I’m busy researching something, or maybe I’m doing a lot of video recording, or I’m waiting around in a train station waiting and I’m playing a lot of games.

The next day, I might not need it anywhere near as much because I’m in a bunch of meetings, and maybe I only watch a video or two on the commute home.

Those two days are not the same, and what’s more, the individual user’s app usage could vary a whole lot. Some apps are platform-specific – you can get Resident Evil IV on an iPhone but not Android, for example – and some are country-specific too, so a test taken where there’s some wildly popular social network that’s very lean on battery life might not apply equally in a place where the social network du jour eats up your battery at a more aggressive pace.

A given app version might be a less optimised beast, meaning that later usage once it’s better behaved delivers a more pleasing result.

That’s a whole heaping load of variability right there, and variability is not the friend of getting accurate results.

I do use anecdotal daily testing myself, and will note where a phone’s battery performance differs wildly from my tested results, but it’s a much more imprecise way to manage battery testing.

So all phone battery tests are just bunkum, then?

Great word, bunkum. Try to use it today in a conversation… but I digress.

No, that’s not the point I’m trying to make.

If you’re looking at a review, whether it’s one of mine or anyone else’s – and I’d suggest you read around widely before making any tech buying decision, because a lot of this stuff is not cheap, especially in the smartphone space – consider what’s been tested and what you’re being told about how that testing has been undertaken.

Also compare it against your own likely usage.

You probably do know if you spend all day on your phone, or it’s just that slab that you stick in your pocket so people can call you. Your battery usage will vary a lot depending where on that kind of sliding scale you sit.

I provide my calculated figures to help both groups as much as possible. If you’re looking at one of my results above 90% for that first hour, every percentage point could lead to hours more of standby time, or many minutes more of app usage.

I have fewer three hour figures, but they’re a decent, but not absolute way to measure more sustained battery usage.

Bear in mind as well that over time the nature of battery chemistry and some of the smart tricks that specific phone models use will affect battery life overall.

Most tests, including mine, are done on brand new phones with brand new batteries, so neither battery degradation or in most cases battery optimisation routines really have a lot of time to kick in. If your 8 year old phone doesn’t hold a charge any more, well, that doesn’t mean it always had a lousy battery.

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