Yato has factories in Poland and Romania
There is also an unhinged option that i've used, and i recommend as long as you know what are you doing, and it involves remaking your tools to accept T-shaped connector (or any other) on a short external cable, and carrying bigger battery with extension cable and the other side of connector in backpack. Alternatively old battery can be remade into backpack battery adapter. No handheld sized battery can get 30Ah capacity. As long as voltage is roughly the same you're good to go (there is natural swing in voltage as battery discharges. you can probably guess internal structure of modern ones as Li-poly 3S to 5S)