If I did the math correctly, if the OP rode at the same pace you did, he'd need just under 6 iPhone charges (about the same for Samsung). So that would be 3 of those batteries you used and that should leave him with a fully charged phone. That's probably good margin in case he needed the phone to make an emergency call or something.

That's a lot of batteries to carry for the phone. If he were to use a bike computer with a 10 hour battery life, he'd probably need a lot less and maybe only that that is about half of one of those batteries you used.

J.