No, I'm not talking about the big money banks, I'm talking about the portable devices you can use to charge electronic devices, like cell phones. We've bought a few of the ones you see at Target and other places for $15-$25 per battery, and it seems like they either won't charge a phone more than half a charge, or the darned things last only a few months of diminishing performance before they don't work at all. Last one I picked up in a bargain bin at the grocery store wasn't worth the $5 I paid for it, as it only put about 15% onto my phone. Anyone have a good power bank they can recommend? Primarily use it for my Samsung Galaxy S7 phone, my iPod, and occasionally my Samsung tablet.