PAU L OCKENDEN
Paul Ockenden gets excited about an update to Flir’s low-end thermal imager, and looks for the magic in fast phone charging
Quick-charging phones aren’t magic, you might be disappointed to discover, but a simple demonstration of physics. Plus, a thermal imager gets Paul hot with excitement.
If you’ve ever seen a picture from a thermal imaging camera, it’s very likely to have come from a Flir model. Although there are a few other players in the market, Flir seems to be spectacularly dominant. The company is nearly 40 years old, and originally set up to provide thermal imaging for aircraft – the kind of things you see whenever the military boasts about a precision missile hit during times of conflict. The Flir name comes from “forward-looking infrared” – the type of camera that’s mounted on a plane.
Airborne cameras are just a small part of the thermal imaging market these days. There are also many handheld cameras, such as those used by emergency and rescue services (for checking fires, or looking for lifesigns after an earthquake), and also for such tasks as environmental surveys of buildings, for example.
Until a few years ago, such cameras cost many thousands of pounds. But in late 2013, Flir disrupted the very market in which it was so dominant. It released a camera known as the Flir One for just over £300. Rather than being a standalone device, it was an attachment for an iPhone, so was able to use the handset’s screen and processor.
The biggest problem with the Flir One was its form factor: it only worked with the iPhone 5 and 5S, which limited both the appeal and the longevity of the product. Apple isn’t known for keeping its iPhone models going for long, and I reckon Flir was remarkably lucky in this respect, with the iPhone SE (which is based on the iPhone 5) still being available four years later.
This restriction was overcome in late 2015, when Flir released a new-generation camera that was available for both iOS and Android phones (and tablets – people often overlook how well these gadgets work when plugged into a bigger screen). It was quite unlike the original Flir One from a couple of years back – but, confusingly, the company still kept the same name. I wrote about it here almost exactly a year ago ( see issue 265, p113).
Now there’s a new, thirdgeneration device that’s just been released here in the UK, which I’ve been testing for a few months. You won’t be surprised to learn that despite it being a completely different device once again, the company is still calling it the Flir One. If nothing else, you have to admire its consistency!
Actually, there’s plenty more to admire. The new version comprises a standard and a Pro model. Online you’ll see enthusiasts referring to the new models as F1G3S and F1G3P; the previous two being F1G1 and F1G2.
The standard F1G3S model is actually a step back from the previous F1G2 model, since it has a lowerresolution sensor (80 x 60 pixels versus 160 x 120), but that’s reflected in its price: at £216 direct from Flir, it’s likely to drop to just below £200 once it becomes widespread in the distribution channel. The F1G2 typically sold for around £300, so that’s quite a significant drop.
However, the more interesting device for me is the new Pro model. It has an RRP of £400 – although, again, I expect it will be available for less once it becomes more widely available.
The Pro has the same 120 x 160-pixel infrared sensor as the
previous version, but the visible spectrum camera that it pairs with has an increased resolution – up from VGA (640 x 480) to 1,440 x 1,080. As with the previous two generations, the thermal and optical images are blended together to create a detailed image.
It’s additional processing, rather than this increased optical resolution, that results in the F1G3P offering significantly better image quality than the F1G2. Flir calls this tech VividIR, and the results are astonishing. You can pick out details using the new model that the second generation will completely miss. I just did a test, in which I walked across a floor bare foot. A minute later, the F1G3P can still discern my footprints on the floor where the F1G2 couldn’t see anything.
A new app accompanies the new hardware (note that it also works with the older models). Some aspects of this software haven’t gone down well with existing users – in particular, the initial requirement of mandatory registration before the camera will allow you to take any pictures. Plenty of other software does this too, but due to the response Flir has since removed the need for such details.
The new app also features social feeds and a selfie mode, neither of which make me excited. It isn’t possible to disable them either, but you can ignore them.
One thing I do like is that it will pair with a smartwatch. So if you need to figure out what’s going on in an awkward space – in an engine compartment, perhaps, or behind a fridge – you can push your phone into the gap with one hand and see the thermal image displayed on your watch face. Ensure watch and phone aren’t at the end of the same limb, though!
The hardware itself isn’t too dissimilar from the previous version, but there are a couple of neat touches. First, the Android version uses USB-C rather than micro-USB; Flir will have a solution for those with the olderstyle socket in a few months. But USB-C tackles the problem with the previous version, where the camera sometimes needed to be reversed depending on which way round the socket was on your phone.
Second, there’s a neat feature where the protruding USB-C plug (or Lightning for iOS) can be wound in and out, so you don’t need to remove your phone from its case to plug it in. This is especially handy for those working on building sites and similar, who keep their phones in thick, rugged protectors.
Overall, I’m really impressed with the new Flir One Pro.
Who’s in charge?
There’s a lot of misinformation and misunderstanding out there when it comes to mobile phone chargers. For example, the other day I overheard a shop assistant telling a customer that a particular USB charger wasn’t suitable for her phone because it “chucks out too much amps”. I suspect my real-life LOL – honestly, I couldn’t help it – made it rather too obvious that I knew the salesman was talking utter nonsense.
When it comes to chargers, you’ll see three figures mentioned: the voltage (V or volts), the current (A or mA for amperes; usually shortened to amps and milliamps), and the power (W or watts; named after the steam engine bloke). The power is simply the voltage multiplied by the current, so 5V at 2A is 10W. And these days you’ll find it’s the power that’s used to distinguish different chargers. So will a 20W charger top up your phone twice as fast as a 10W model? Possibly yes, but probably not. To discover why, we need to think a little more about current and voltage.
Some people will tell you to think of it like a river: the voltage being how fast the river is flowing, and the amps are how wide and deep the river is. Multiply them together to get the power; the amount of water passing through. Except that’s probably the worst analogy you’re ever likely to hear. I’m not even sure there’s a good analogy - I remember my old O-level physics teacher telling me to think of voltage as if it was height, or altitude, and current as if it was weight. But that just reinforces the shop assistant’s assertion that too many amps would damage a phone.
My advice is to forget all these analogies! Just remember that the primary consideration with a phone (or, indeed, any other charger or power supply) is that it delivers the correct voltage. Any lower and the device won’t charge; any higher and the device will be damaged – possibly with some flames and smoke involved! There may be a small degree of tolerance, but in general, the charger voltage needs to be what the device is designed to accept.
Then we come to the current. A phone with a drained battery will have a maximum current it can draw from a charger. Let’s take an example of a phone that’s looking for 5 volts at 1 amp. If the charger is rated for 5V and 2A, this really doesn’t matter (provided it’s a decent-quality modern charger) – the phone will simply draw 1A of the available 2A.
So think of the rated voltage of the charger as a fixed value, and the current as a maximum – this is really what the salesperson in the shop should have known. The voltage has to be right, and the current output should ideally match what the phone needs, but if there’s more available then it won’t hurt (or be used).
But what happens with an under-rated charger? What if our phone wants 5V at 1A but our charger is only rated for 5V at 500mA (or 0.5A)? Well, to a large extent this depends on the charger. Cheap, old or poor-quality chargers might overheat as they struggle to deliver the current being demanded, but the vast majority of chargers on the market today will simply limit their
“The primary consideration with a phone charger is that it delivers the correct voltage”
current and your phone will charge at a slower rate.
For safety reasons, and also to maximise the life of your battery, your phone will probably vary the current it draws throughout the charging cycle. When the battery is empty, it will fill up rapidly – but, typically, when half-full the charging current will be reduced, falling further as the battery reaches full capacity.
This is best practice, but the way some phones try to achieve a faster charge time is by upping the point at which the charging current starts to ramp down. 60% and 70% aren’t uncommon, and some phones are pushing towards 80% before the charging current reduces. I do worry about the longevity of the batteries in these phones.
However, a problem is that with greater current comes greater heating in the wire that connects your charger to your phone, and in the connectors, internal wiring, and so on. This heating effect doesn’t depend on the voltage – only the current. It’s why fuses – which are designed to melt a thin wire when it gets hot – are rated in amps rather than watts; a fuse doesn’t care what voltage it’s working at. So the greater the current, the faster the phone charges, but also the more heat is generated. There is a way round this problem, however, which I’ll come onto in a bit.
Of course, people want their phones to charge as quickly as possible, and so over time, there have been many schemes devised to achieve this. Some (notably Apple) just get on with it, while others have fancy names such as Qualcomm’s Quick Charge, OnePlus’ Dash Charge, Oppo’s VOOC, Samsung’s Fast Adaptive Charge, Huawei’s SuperCharge, or Power Delivery as part of the USB-C standard. But none of these is magic – charging is all about getting power into a battery, and as I mentioned above, power is simply voltage multiplied by current. It’s basic physics. These fast-charging schemes simply allow greater charging power.
To avoid heating cables and connectors, some of these systems deliver a higher voltage (and so reduced current, for a given power level), with the voltage then being reduced to what’s needed within the phone itself. It’s a bit like how the National Grid works – high voltages (with low losses) for long cable runs, reduced down to usable voltages locally.
In phones, this voltage reduction is often provided as part of the SoC (System on a Chip) at the heart of the phone. Take Quick Charge, for example. The original version was supported by the Snapdragon 600 SoC – that was just 5V at 2A (so 10W). The 800 series along with the 610 and others brought Quick Charge 2, which added 9V at 2A and 12V at 1.67A (18W). Quick Charge 3 remained at 18W, but brought in a dynamic voltage ability, allowing it to vary anywhere between 3.6V and 20V – it was supported by the Snapdragon 620 and 820 processors, among others. The latest Snapdragon 835 supports Quick Charge 4, but there’s little reliable detail available about that, because despite many phones using this processor, most limit their charging to lower standards.
The Samsung Galaxy S8/S8+, for example, employs a Snapdragon 835 (or Samsung’s own, closely related Exynos 8895 SoC), and uses Samsung Fast Adaptive Charge, which is based on Quick Charge 2. Following the Note 7 fiasco, many manufacturers – Samsung, in particular – are being super-cautious when it comes to battery charging; and rightly so. Many other 835-powered phones also eschew the latest version of Quick Charge.
One unwanted side effect of upping the voltage to reduce the current is that the phone becomes warmer because it then needs to reduce the voltage back down again. It’s why Quick Charge-equipped phones will often drop back to a slower charge if you’re using the phone at the same time as charging it.
To avoid this, OnePlus and its parent company Oppo use heftier wires and send 4A down a fatter than normal charging cable. It also beefs up the contacts in the special USB plugs to avoid heating issues there, too. It seems to work well – a fast-charging OnePlus phone stays noticeably cooler than many other flagship devices. And the phone continues to fast charge even if you’re checking your emails or playing a game.
If you’re interested in looking at the charge going into your phone, I recommend a USB Power Meter. Plug it in between your charger and the lead that goes to your phone. I’ve tested a few of these over the years. The one I’d currently recommend is the Muker-J7, which costs £10 from Amazon ( pcpro.link/277muk).
You can plug it in either way round, so you’ll always be able to see the display. It also has built-in memory, so if you accidentally pull the power while measuring the capacity of an external battery pack, say, it will resume properly when the power is re-applied. Strangely, it says “USB Security Tester” on the case – I’ve no idea why!
It’s only once you start to look at the numbers on a device such as this that you realise that there’s no special magic to fast charging a phone. It’s all about delivering power – watts – to the battery as quickly but safely as possible.
“The greater the current, the faster the phone charges, but also the more heat is generated”