If it has a lithium metal battery with more than 2 grams of lithium it in you can't carry the battery on the plane. This is a new rule instituted in the last couple of weeks. If it has lithium ion batteries you are good to go in your carry-on. This assumes you are flying out of the US. A quick google on EPIRB batteries shows that they use lithium metal batteries and copnsequently may be forbidden on planes as of November 1 or so this year.

I would contact the TSA and ask specifically. You might also want to contact the manufacturer of your EPIRB to get the details on the type of bettery in it