If any of your standard fees listed in your fee schedule, brochures etc. can be charged against your "free" account, then the account is not free.
It's not that simple. Wire transfer fees are not activity or maintenance fees, so charging for wires won't endanger your use of the work "free."
I recommend that you review comments 3-8 to section 230.8(a) in
Supplement I to Regulation DD. There, you'll find detailed information on what will and what will not cause problems for you.