The Things [wireless power] Marketers Say

22 January 2019

On Jan 12, 2019, the Oklahoma City Thunder played an NBA basketball game against the San Antonio Spurs. It was a good game, though not an extraordinary one. San Antonio threw for 243 points and lost.

How can that be? Throw for 243 points and lose an NBA game?

Here’s the deal: I didn’t say they scored 243 points. I said they threw for 243 points. According to the official NBA Box Score, San Antonio had 96 field goal attempts, of which 65 were for two points and 31 were for three points, as well as 20 free-point attempts. 31×3 + 65×2 + 20 = 243. While throwing for 243, they actually scored only 112 points (10 three-point shots, 34 two-point shots, and 14 free throws). Obviously, the truly important figure is how many points they scored, not how many points they threw for.

Which brings us to wireless power and how it’s marketed. When a vendor tells you “our wireless power transmitter sends 10 Watts into the air”, that may be interesting but it’s less important than “how much energy is available to the device being powered?”. If you’re sending 10 Watts into the air and only 10 milliwatts are available to the device, it’s the 10 milliwatts that truly matter.

Of course, this is not the first field in which marketers pick larger numbers with less meaning. For instance, if you’re considering buying a new TV, one important parameter is how large it is so that you can make sure it fits where you want to install it. A 60″ television with a 16:9 aspect ratio has a 52″ horizontal and 30″ vertical size (I looked it up here). In reality, people care more about the 52″ than the 60″, but the 60″ just sounds more impressive.

So when you look at wireless power options, you might want to ask some of the following to help cut through the marketing:

  • How much power is available for the device being charged?
  • At what distance?
  • What safety certifications have you obtained?
  • What happens to all the energy that is sent from the transmitter and is not available for the device being charged?

That will get you to the truth faster.

p.s. there is some value in looking at the 243 points that San Antonio attempted, but this is mostly fuel for basketball analytics experts, like this Reddit user


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