Cigarette Lighter Inverter

I am driving a 2013 KW for Navajo. I want to get an inverter for it that plugs into one of the cigarette lighters, and has one plug. I want to get it at Walmart. I want to use it to recharge my cell phone and later on plug in my laptop. Can anyone tell me if that will drain the power of the battery, or do any kind of damage to the truck.. I know nothing about mechanics or electrical systems.

I have one, I bought at pilot it charges my laptop, my e cig and my phone. always in use. it is 100 watt and has never killed my truck battery. even when on a 34

I bought a 480W Cobra in Pilot, was planning to use with my rice cooker(claimed 250W), but turned out it couldn't stand the power drain from the cooker, and fried the first one (exchanged with a new one thanks to Pilot), so I am using it as my laptop charger solely. I use a Fuse twin USB charger for iPhone and iPad.