Least Battery Expensive Tethered Networking Options

[RumorConsumer]

I just had this idea pop up

If you have a MBP and an iPhone there are two ways to tether - over USB or over Wifi. Oftentimes when Im tethering Im on the road as a passenger or in a vehicle of some kind.

Scenario A: Ive got the wifi on my Mac and my iPhone and Im tether to the Mac wirelessly and the Phone is handling its own power source - cigarette lighter or battery power. Mac isn't supplying any power to iPhone but it is powering its wifi chip.

Scenario B: Mac is connected via USB to the iPhone which is tethering over USB and unavoidably drawing current from the Mac over the same USB cable. Wifi chip is off on the Mac.

Which of these two scenarios will drain my Mac's battery fastest?

 

[sevoneone]

It is hard to say. Under different conditions the best option will likely vary, but I am going to say wireless will probably be the better choice most of the time. Because the devices are so close together their transmission power for wifi should be pretty low. There are more variables if you are plugged in like Cellular signal strength: Less signal means the phone will be applying more gain to the cell radio and pulling more power. The charge level of your iPhone while it is plugged into your Mac will also be a factor. A lower battery is thirstier than one that is nearly full and will charge faster, using more power gradually slowing.

 

[cruisin]

There is a third way using Bluetooth, but it is slow and likely less efficient then WiFi. It was great to use (if you are ok with the speed) as clicking a Bluetooth menu on the Mac would connect to the iPhone without needing to unlock the iPhone and go into settings and enabling hotspot. Now that there is a one click way to tether over WiFi the Bluetooth way is less useful.

If the phone is fully charged, then tethering over USB will use less power. You would be just using the iPhone cellular, and the phone (with the screen off) will just take a small amount to handle data. Otherwise, the iPhone can request up to 2.1A from a modern MacBook to charge itself.

Check out the power draw by plugging in an iPhone and clicking  > About This Mac > System Report > Hardware > USB > iPhone. It will show 0.5A as the base power draw and then it will state how much extra operating current it requested.

I think running the WiFi on the MacBook is less expensive, as tethering over USB will drain the battery for charging the phone. Plus you don't want to use one battery to charge another, as that process isn't efficient.