As mentioned, don't go the route of buying some battery pack (powerbank) to use this to power a charger, I had some batteries at home here from super soco, these had the same shape as the cux batteries, and where 60v/43ah, they where higher then the original cux batteries looking at pictures, I never found out where these were used for originally, but they are plenty availible in holland on market sites.

These batteries where also compatible with the super soco display. I tried one of them in a super soco ts, but i went another route because i wanted more current for power output.

Thanks Arjan, funnily enough I've just seen a 60v/43ah battery pop up on ebay, the seller saying its from a cpx, but it is a different shape to my battery.

What would the advantage be of a 60v/43ah over my 60v/30ah original? Would it potentially give more range?

You can swap the internal fan in the charger for Noctua NF-A4x10 and make it much quieter with slightly better airflow too