I haven't had a customer ask this yet, but currently a majority of the ADA handicapped push buttons for door openners we install are wireless and battery powered; I did a little bit of web searching but as with most things access control related, you pretty much have to know what you're looking for, before you start searching.
Has anyone run across or used a battery powered, wireless prox reader? We typically use HID E400 Edge door controllers so it would only have to send the signal 10-15 feet to a receiver that we would wire to the reader input of the controller, just like the wireless pushbuttons. I have to think something like this exists. I am not looking for wireless/Wi-fi integrated locksets like the Assa Abbloy Harmony or Schlage AD-400 wireless units.