It's important to differentiate between the different types of beacons.
The ULB (Ultrasonic Locator Beacons) are fitted to the front of the DFDR and (optionally) on the CVR. These are specifically designed for underwater operation and will only activate on contact with water. These are powered by replaceable, not rechargeable batteries. The range varies with the water condition. The beacon is only certified down to a certain depth (I guess it will crush at lower depths). Ours are certified to 20,000'. The range, for some reason, is quoted in meters (1800~3000)
There are portable ELB's stowed in the cabin at various locations. These are usually activated by water, but are not designed to transmit underwater. These are designed to float on the surface of the water. The water usually dissolves a paper/cardboard collar holding a folded antenna in place. When the collar releases, the antenna springs up and the transmitter starts operating. If there is no water at the crash site, the collar can be broken manually.
Finally.. the latest and greatest ... are the fixed ELT's mounted on top of the fuselage (the blade-type antenna is just forward of the vertical stabiliser/fin on the outside of the aircraft and the transmitter/battery is mounted just below it). These are g-force activated. A PPRuNer quotes 5g's for 11milliseconds in any plane/direction. These can also be manually activated and reset by a switch on the cockpit overhead panel. These are also not designed to operate underwater. These send signals on VHF and UHF. The UHF, I imagine, will be picked up by satellite. The UHF signal contains the aircraft ID, but not a GPS position.
Rgds.
NSEU