Power pack

What is the actual meaning of "power pack" :?:

I've seen it somewhere, given to a certain converter (inverter?), powered by batteries or small cells. Or it is only the box containing the batteries or cells?

Should I expect different meanings depending where in the world this expresion is used? USA, UK, ...?

Agustín Tomás

I first heard the expression in the 50s when it meant the mains power supply section of whatever equipment it was in reference to.
It wouldn't surprise me, though, if nowadays it was used for either a mains driven supply or a battery source.