Just use your credit card

And adding to this: using the card gives me peace of mind because it never runs out of battery. If I only used my phone for payments and it died while I was out, I would be screwed. Can't call a friend, can't pay for transit, I guess I'm walking for hours to get home? Since I use the card to pay, if my phone dies, the worst thing that happens to me is I might need to look at a physical map to figure out which train to take home.