dreigriff often translates as "triple control" but I'm not sure about "Entleerungsbatterie"

This could be a way of saying that it's a battery which is intended to be drained (entleert) and charged for use again, i.e. a rechargeable battery, as opposed to one you dispose of once it's drained.

From a bit of googling, this appears to be a plumbing fixture (tap or faucet) similar to an Entleerungsarmatur. The Dreigriff part means it has three knobs (which can probably be translated as 'three-control'), and at a guess 'Batterie' means they are arranged in a row (instead of radially as in many designs with only two controls).
The Entleerungs part apparently relates to the fact that it would typically be used with a wall-mounted boiler (water heater) and fitted below the boiler, so it effectively 'discharges' or drains the boiler.
Boilers of this sort (also called geysers) are practically unheard of in NA, and they seem to be regarded as antique curiosities in the UK now, but they are still fairly common in Germany and NL.

That all being said, I don't know what a plumber would call this particular type of fixuture.