My 2012 JKU did exactly what your Jeep is doing and I found out it was the ground terminal connection on my battery post.
It was just slightly loose so I took the ground terminal, (Cheap OEM Chinese Pot Metal), off and squeezed it with some pliers and put it back on.
It fixed the problem for about 5-6 months and started happening again so I went to the auto parts store and bought a set of those lead battery post ex-panders and put it on my ground post. When I put my ground terminal on my battery post, I had to gingerly beat the terminal on with a rubber mallet and I never had any problems ever again!
PS: Just traded the 2012 JKU in for a 2015 JKUR! Got top dollar for my trade-in and a really good deal on the Rubicon!