IoT WiFi vs Bluetooth: Power Consumption

My first post on WiFi vs Bluetooth ignited a fierce discussion. So let's continue this interesting debate. Today about power consumption: this one is rather obvious. Bluetooth Smart has been designed to run connected sensors on coin batteries for years. And it delivers on that promise. Even with the current generation of Bluetooth Smart chipsets, it is possible to bring the average current draw below 20uA with 1Hz reporting frequency. This means more than 4 years lifetime on a single CR2477 coin battery (assuming 800mAh battery capacity, 800/0.02/24/365=4.56). This is roughly speaking 10x-20x better than the same application on WiFi. Today it is simply not possible to build a battery - powered WiFi device that will last at least one year with decent responsiveness.

Wanna proof? Look at what Lockitron is saying about the Electric Imp WiFi module:

A little back story on WiFi - when we originally announced WiFi, the power consumption estimates presented to us by potential WiFi suppliers were roughly 2x-5x lower than what we’re seeing in various real-world scenarios. This meant that with a little bit of sleep we could wake up Lockitron’s WiFi pretty often. However, when we started working with the folks at Electric Imp we learned from them this simply wasn’t the case for a number of reasons and we’ve had to dial back how often Lockitron connects via WiFi.

What Lockitron should have done from the very beginning was to design their lock with Bluetooth Smart only and make a small Bluetooth-To-Cloud gateway sitting in a wall socket.

WiFi has not been designed for IoT. WiFi is high throughput, streaming protocol. IoT is mostly about tiny data packets carrying just a few bits of information. Especially using WiFi for battery powered devices is like flying just a few passengers with a 747. It just does not make sense. Bluetooth Smart is like Citation or Gulfstream. Designed for specific scenarios, and fits most IoT perfectly.