The double-pronged approach to Qi wireless charging

One of the most satisfying things in life can be to take something old and make it shiny again. No, not just a physical clean up (though that helps), not just a software update (also useful!) but adding actual functionality. In this case, taking a classic smartphone and adding in Qi wireless charging – with Qi plates in the office and at home (and sometimes in coffee shops), in theory your smartphone can always be snacking on power and thus always ready for maximum action.

You may remember a little hackery along these same lines for the ageing Samsung Galaxy  Note II last year? In that case, I tested an after-market coil, concluding that it worked pretty well, if slowly, with installation that was practical, if a little fiddly. In this case, I’m going to go one better and explore both official and after-market options for the slightly newer (but still well out of warranty) Samsung Galaxy S4, with a nod to the current S5, for which almost identical options apply.

It may strike you as odd that Qi charging retrofit articles here and around the web are nearly always centred on the Samsung smartphones, but these have external charging pins available under their covers, for exactly this purpose. Most other smartphones are either sealed, in which case they either support Qi charging – or not, or simply don’t have the appropriate pins that can be hooked up.

Most of us make do with charging our phones once a day, usually at night, with the occasional top-up during the day if we feel we’re going to run out of juice. Wireless charging changes everything, in that your natural resting place for your phone on your desk at work, or in your car, or in your kitchen – they can all be charging plates, ensuring that your phone battery is being kept constantly topped up. Li-Ion batteries love being topped up – and often – as I explained here, so wireless charging is a match made in heaven.

Charging
Happily charging, resting on my desk….

In a real world environment, with a couple of wireless charging plates around the home and office, my smartphone rarely dips below about 70%, whatever time of day you care to look at it. Almost every time it’s put down, there’s energy being poured back into it, without any tedious fiddling around with microUSB connectors, making sure they’re the right way round and then gingerly easing them into position.

The downside of wireless charging is that it’s less efficient than wired charging (i.e. some extra heat is generated), so if the fate of Planet Earth depended on it and five billion people charged wirelessly then we might be in trouble. But I think you and I can get away with it in 2014!

Despite me proclaiming that wireless charging is the future, there remain at least two standards. Rather curiously, one (Duracell Powermat) is used by almost no one and yet pushed a lot by the industry in terms of test installations in transit lounges, while the other (Qi) is used by almost everyone and yet you can’t find a public Qi charging spot for love nor money. Regardless, the latter will win, since it’s got Google, Samsung, LG and Nokia behind it. And if Apple ever throws its hat into the ring as well….

But on with today’s experiments. I’m fascinated that, for each of Samsung’s flagships, there are two completely different ways to go in terms of adding wireless charging. There’s the official case, shown below, and there’s the ultra-thin after-market version, shown further below and coming in at a much lower price. Yet both perform almost identically. So which way should you go, whether for a Galaxy S4, as here, or a Galaxy S5 (for which the exact same options exist, albeit with slightly different part numbers)?

Scharge
The Samsung ‘S Charger Cover’

The official solution, the “S Charger Cover”, is a whole new replacement back, adding around 2mm to the (in this case) Galaxy S4. It fits well though, as indeed it should, coming direct from Samsung. The coils that are integral are rated at 650mA (at 5V), which equate to about a 20% charge per hour on the 2600mAh S4. Compare this with up to 50% per hour being added via traditional wired charging from the Samsung mains adapter.

In place
Showing the extra thickness, the camera ‘hump’ is now a depression….!

Interestingly, there are other pins and shiny panels on the inside of the S Charger Cover – but I’ll come to those in a moment.

The low-tech alternative is to opt for an after-market ‘coil and cable’ assembly, as shown here:

Coil assembly
The underside of the coil assembly, with a small adhesive strip….

This is rated almost as highly, at 600mA, so there’s little in it in terms of performance. The unique selling point here, other than a lower price, is that this can (as with the Note II featured before) be slipped in underneath a standard phone back cover – just. You line up the charging pins (which are again a loose fit, relying largely on pressure from the back cover in order to keep a good contact), press down the small strip of adhesive onto your battery and you’re done. Getting a standard back cover on again is a little harder – it’s clear that the extra thickness causes the plastic back to bow out a little and you’ll have to work a bit harder to get all the cover clips snapped into place.

Coils 2
In place – a little ugly – and the microSD slot is blocked, but the adhesive is only for the battery – take this out and the coils and flex come too…!

In use, both solutions work well – 20% per hour isn’t for anyone in a hurry, but for regular top ups while you’re working or relaxing nearby it’s ideal.

However, there’s one catch to all this – because NFC on the Galaxy S4 is in the battery, the after-market coils block the NFC antenna – meaning that with the Qi charging accessory in place you can’t go around tapping things! And this explains the extra pins in the back of the official Samsung accessory.

You see, as with charging, Samsung provides NFC aerial input pins too – they’re clearly belt and braces people! So the S Charger Cover has extra NFC aerial panels, top and bottom (they’re connected, internally), to channel NFC data/energy through to the pins. Meaning you don’t lose NFC functionality when deciding to retrofit wireless charging in this way.

NFC components
Shiny new NFC aerials and pins, as part of the S Charger Cover…. The Qi coils are bang in the middle…

In summary, then – whether you have a Galaxy S4 or S5 – you have two options:

  • The official Samsung solution which costs more and adds bulk
  • A third party ‘stick-on’ internal solution which costs less and adds less bulk, but also stops you using NFC

For those who never use NFC anyway, this is something of a no-brainer. And if you come across a NFC tag/point, just take the back cover and coil off temporarily? Alternatively, if an extra 1mm is neither here nor there and you want to be ready should NFC take off, then the Samsung solution can also be recommended.

PS. Given the two solutions and the way the add-on coil hooks up with its two metal prongs, do you see now what I did with the article title?(!)

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Thanks to Mobile Fun for the review samples of their Qi wireless chargers.