How to Add Wireless Charging to Your Boat
Unplug—For Good!
Who needs wires snaking all over the place to keep your phone juiced?
Declutter with a simple wireless charger.
They used to say a dog was a man’s best friend—but not any longer: For many people, the best friend is a cellphone. Cellphones don’t eat, they don’t need walking, they don’t need to see the vet, and they don’t wake you at midnight barking at something on the stairs that only they can see. (Got ghosts?) But one thing a loyal cellphone, or its cousin, the tablet, demands is electricity: Its minuscule battery needs frequent feeding with low-voltage juice at least every night for most folks, and more often for some. That means a snaky USB cord, plugged into a computer or a power adapter that is itself plugged into a 120-volt outlet. Frequent plugging and unplugging eventually damages the cord, and sometimes the phone’s port, too, and dealing with the paraphernalia takes away some of the convenience of carrying a supercomputer in your pocket.
The answer? Lose the wires and the adapter and much of the annoyance by investing in a wireless charging pad. Charging pads are built by plenty of companies, but most aren’t suitable for marine use—water and shoreside electronics rarely mix well. But choose a waterproof pad, one designed specifically for boats, and you can even use it in the rain. Cordless charging works through water, through the case on your phone, through almost anything that’s non-metallic and less than five millimeters thick. And the charging pad can be mounted almost anywhere, even at an open helm station.
Rather than stowing your phone in a drink holder, or keeping it in your back pocket at the risk of butt-dialing someone in Kuala Lumpur, I’d recommend installing a pad on the console that will clasp the phone securely so it doesn’t fly overboard even in boisterous conditions, recharging it at the same time, but keeping it handy in case your broker calls. For calmer conditions, a simple pad screwed or glued onto any flat surface will do the trick, or, if you’re into the minimalist look, you can place the pad out of sight under a countertop. Charging pads aren’t costly, and installation is simple—basically, just connect two wires to a fused and switched source of DC power, place the phone on the pad and electromagnetic induction does the rest. When the phone is fully charged, the pad will switch to standby mode. Some experts claim that the frequent top-ups you get with leaving the phone on a wireless charging pad will extend the life of its battery. (Honestly, before the battery dies its final death, you’ll probably be ready for a new phone anyway.) ρ
Remember High School Physics?
Cordless charging doesn’t transfer electrons into the phone battery; it just rearranges the ones that are there, using a basic principle of electricity. Electrons flowing through a wire generate a magnetic field around that wire; the direction of current flow determines the polarity of the field. Passing a second wire through that magnetic field generates a current in that wire, too. (If you want to know more about this, and you like formulas with a lot of Greek letters, research Faraday’s Law.) In practice, usually the wires are stationary but the magnetic field—the flux—moves, due to changes in polarity of the alternating current feeding the primary wire. Energizing a coil of wire with AC will induce similar AC current in a second coil placed near it. (That’s how a transformer works.) A wireless charging system is essentially two coils of wire, the primary coil in the charging pad and the secondary coil in the phone, or sometimes tablet, being charged. Placing the phone on the energized pad induces current in the phone’s coils. (Tip: The charger itself generates a magnetic field, albeit a very weak one, so unless you mount it right next to the compass it’ll have no effect.)
“But,” I hear you ask, “if the pad is connected to the boat’s DC wiring, where does the AC come from, to create the changing flux necessary for electromagnetic induction?” Well, the pad has an electronic inverter that changes the DC input into AC before feeding it into the coil. The current generated in the phone is also AC, and is changed back to DC by a rectifier. Only DC can be used to charge a battery. The AC adapter you plug into the wall socket does the AC/DC trick when you’re charging by wire, and switching between AC and DC is common in all electronics, only we don’t realize it. Anything with transistors, which means almost every electronic device, is powered with DC, even if it’s plugged into an AC outlet; transistors work only on direct current.
One charging pad can serve many phones. An Apple iPhone has different innards than a Samsung or Motorola or LG phone. But phones from all four manufacturers, and most others, too, can all charge from the same pad, and from pads built by a number of manufacturers. This is thanks to Qi, a standard charging protocol developed by members of the Wireless Power Consortium, an organization of more than 350 member companies committed to the development of wireless charging. All products using the Qi standard (Qi, pronounced “chee,” is a Chinese word usually defined as “vital energy”; it’s an Eastern thing) can play well with each other: Any Qi-certified phone can charge from any Qi-certified wireless charger. If your phone doesn’t have built-in wireless charging, you can add it with an inexpensive Qi-certified plug-in adapter.
Positioning Is Everything
One downside, and maybe the only one, to wireless charging is its lower efficiency vs. wired charging: There is some power loss through the induction process. Folks who are experts in this technology say to figure on wireless charging taking from 30 to 80 percent longer than wired charging. The actual number depends on the separation of the phone and the pad—more than 4 or 5mm apart and the charge rate falls quickly; how precisely the phone is placed onto the pad; and the wattage of the pad—most pads are 5W or 10W maximum output, but the phone determines the effective charging power, not the pad. Ten watts is plenty for most phones.
Positioning is everything when it comes to efficient cordless charging, so it’s even more important to place the phone on the pad accurately. Plunk the phone down haphazardly with the coils misaligned, and charging will take a long time. A charging pad that holds the phone precisely in place is a big advantage, especially on a moving boat whose motion will easily dislodge an unsecured phone. One pad that does this is the ROKK Wireless Edge from Scanstrut.
Scanstrut builds mounts for all kinds of things—radar scanners, satcoms, multifunction displays, cameras—and ten different ROKK charging pads. According to Grant Fox, the company’s head of marketing, the ROKK pads are the first ones designed specifically for use onboard; they are waterproof to IPX6 standard, and Qi certified. IPX6 certifies the product has been tested for protection against water ingress when sprayed with water from all directions for three minutes at pressure of at least 15 psi; in other words, it’s more waterproof than you’ll need unless things really go bad. (The X means the product hasn’t been tested against solid particles.) All ROKK pads use the same 10W chargers, but in different designs, including conventional non-skid-surfaced pads that the phone simply rests on, pads in recessed housings, and pads that hold the phone securely by clamping. Other companies also build waterproof wireless chargers—AquaAmp and RAM Mounts are two—but Scanstrut seems to have the best variety of designs.
Scanstrut builds three chargers that grip your phone, but only the ROKK Wireless Edge ($179) is adjustable. You can change the incline for maximum view-ability, and rotate the phone between portrait and landscape orientations, handy if you want to use a charting app while the phone charges. Installation is easy, requiring drilling three holes for the mounting bolts and one for the wiring. Connect to a switched power source and you’re ready to charge. (All ROKK chargers operate at 12 to 24v DC) Just snap the phone into place and the spring-loaded jaws will keep it secure.
Of course, the downside of wireless charging is the length of time it takes compared to wired charging. For most folks, this isn’t an issue—the phone sits on the pad gradually recharging, and you pick it up and use it when needed. But if you’re in a rush, or you have a tablet or other device that requires wired charging, add a waterproof 12-volt USB charger, too. Scanstrut builds them, as do many other companies. Scanstrut’s chargers are waterproof even with cables plugged in; not all “waterproof” chargers are. A marine USB charger is inexpensive and easy to install. Choose one with USB-A and -C ports; USB-C will be the standard within the next couple of years.
With a few bucks and a little effort, you’ll be on the cutting edge of charging technology, and free of those annoying wires—at least when you’re on the boat. (You’ll probably want to add a wireless charger at home, too.) You won’t damage your phone by constant plugging and unplugging, your phone will always be charged and ready to go, and you might even add to the health of your battery. It’s the least you can do for your new best friend.
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This article originally appeared in the June 2023 issue of Power & Motoryacht magazine.
Source: https://www.powerandmotoryacht.com/maintenance/how-to-add-wireless-charging-to-your-boat
