Normally when I'm recording video with my iPhone 7 Plus I have it in my MoVo smartphone holder attached to a DIY PVC pipe "handle" with 1/4-20 bolt. However, if I need an external mic other than my Røde SmartLav+ (not shown), I can use the Røde VideoMicro with its supplied dead cat muffler in the cold shoe mount on top of the MoVo holder. But there are two problems when recording with a smartphone: running out of storage space and power. Even with a 32GB iPhone 7 Plus, I usually only have 6 to 9GB free so my 64GB SanDisk IXpand drive is a godsend. For charging the iPhone, I always bring my Anker PowerCore+, 3350mAh Lipstick-Sized Portable Charger, but have been looking for a way to attach it to the "kit" assembly. I bought 7" (18cm) hook and loop straps but they don't hold the Anker "stick." It slips out. Heavy rubber bands, however, came to the rescue as a "guerrilla" solution.
I have another smartphone holder - a Ulanzi ST-03 - and with it I can crisscross two hook and loop straps to hold the charger as shown in the pictures. I love using either holder with my homemade "handle" as I inevitably get a left hand finger in the frame when I try to shoot video without a holder. And, of course, I can remove my PVC handle and attach the rig to any tripod.