1 BAR IS ATMOSPHERE 14LB PSI pressure. 10 bar is 140 psi. I suppose you could use one of those small 12 volt compressors. Is there some kind of regulating valve incorporated in this system?
If you were a member of a dive club, or have access to dive tank filling, you could decant off a dive cylinder, but as you have 250 bar in some of these, you would have to have to have a regulator and really know what you were doing.
As they are designed for everyday use, there must be a simpler way.
Have you tried Googling the make and model number?