I bought a spare battery and charger of this guy before for a ( Halfords) Pendleton. The original 5 pin charger was joycube sslc084v42xh model but replacement was almost identical and worked fine.
https://www.ebay.co.uk/itm/Joycube-Ladegerat-Akku-E-Bike-36-Volt-2-A-Rundstecker-Fischer-PHYLION-SF-03/392105310931
https://www.ebay.co.uk/itm/Joycube-Ladegerat-Akku-E-Bike-36-Volt-2-A-Rundstecker-Fischer-PHYLION-SF-03/392105310931