Without make and model, I couldn't tell you what voltage it is or how
it's wired to the sockets. If you open up the cover plate there should
be a wiring diagram to tell you everything you need to know
If I disconnect power to the fixture, will the battery module wires
still have 220V on them? I want to avoid a shock when disconnecting
the battery module.
*Yes there will be power coming out of the battery pack once it has been
disconnected. Usually there is a disconnect for the battery by means of a
wire connection. You may see two wires joined together with factory
terminals. Just separate them and it will kill the battery output. It may
be near the test button. As RBM stated, look at the wiring diagram on the
battery and the ballast.
*BTW the battery is there to provide egress lighting when the power goes
out. This is usually a code requirement. The center tube lighting at half
brightness is normal. It is suppose to provide just enough light to exit
the building. The battery back up does not light up all of the tubes.
If you want to be able to shut the fixtures off without the batteries
activating, you need to provide a separate, unswitched feed to those
batteries from the same circuit.
No. The battery is (probably) 12v. It's certainly not 220v.
The wires going to the battery will be no more dangerous than changing the
batteries in a flashlight.