How to prevent Nexus 7 of charging the battery every time when connected to a USB? Hello fellow Android enthusasts,

I recently bought a Nexus7 that I want to use for development. The thing is, every time I connect it to my USB, in order to test some apps on it, it starts charging. Now, i know that this is absolutely normal for every device, but I am also concerned that the constant charge/discharge cycles can shorten the life of the battery. What do I do?

Do I need to get concerned at all? I mean, if it reduces battery life with something like 1% per year, I am totally fine with it. Yet, if it is a significant drain, how can I prevent it from charging unless I am charging from a charger?
Charge/discharge cycles are mostly irrelevant for li-ion batteries.  The main source of capacity loss is simply time.  A li-ion battery sitting unused in storage will lose 15-20% of its capacity per year (see charts on page 4).  Any minor losses from cycling is going to get drowned out by that.