Don't charge iphone when plugged into macbook?

Is it possible to temporarily keep your iPhone from draining the macbook battery? When I'm out and about I sometimes want to connect my [nearly empty] macbook to my [not so empty] iphone so I can tether without using WiFi (saving battery), but then my poor macbook starts charging my iPhone and is drained even faster.

Solution 1:

Not possible, you would have to physically alter the USB cord and remove the pins related to power and leave the data ones intact.

Solution 2:

That's not possible. Also, modifying a USB cable (as suggested in another answer) is a) probably not a good idea and b) probably won't even work (see this question & answer). Energy-wise, you are most likely better of by just using wifi for tethering.