I've bought 3 different portable speakers and this is by far the best I've purchased durability a plus battery a plus sound quality off the charts this is the one your look for!
I bought 2 Bose SoundLink Flex Portable Speakers (2nd Gen), and I use them in stereo mode while playing golf, placing one in the front dash and the other one in the back basket. The sound has amazing clarity with great bass. The battery life is great and lasts longer than a four hour round. The speakers also sound great at home in my bedroom. The only negative is that I cannot link both speakers with a Bose soundbar for surround sound. That incapability prevents me from otherwise purchasing a Bose soundbar.