Have a couple of trips lining up that will put me out of range for 3-7 days and need to get a portable/very reliable means of charging cell phones/other devices for our small crew. They’ll be turned off most times but used for nav, weather, emergency, etc and want a contingency plan, even if never utilized. Several I’ve seen reviewed were good, but could just as well crap out after 3-4 uses. Any direct experience to relate greatly appreciated.