This battery type is long discontinued. If this is the old 22.5 Volt
battery. You can make one.

Get 15 of the small Lithium type watch batteries. Find a piece of small
cardboard or plastic tubing of the right diameter to hold the batteries
in series. Make a pressure contact to fit anb be fasened at each end.

This should serve as your battery for the meter. I have done this for
older photographic equipment and older radios.

Jerry G.