@chuck34108 Yes, I would advise using a data blocker. I rely on my phone for this (if what you're charging is a phone and that's a feature). Or power off the device being charged if it will charge in that state. Another thing: charge your "dumb" battery, then use that to charge your device.
@chuck34108 Sounds like you could really use a few portable batteries. I like HALO brand, decent prices on QVC (crazy huh?). Can recharge a phone 3-5 times from near 0 to over 90% on the 3 I own.
Safe & Happy travels!
@Vanitas I have a few of those, too really like Anker products.