The phx21 charger (LDAR# 762) is end-of-life by the original manufacturer. Any orders placed after the last charger has shipped will be canceled. 
If you need to source a charger to support your existing units, the following components are required:
Circular Connector: PX0410/08S/6065
Circular Connector Contact: SA3347/1
12V 700mA smart charger
A simple drawing showing applicable pin placement is here phx21-charger wire diagram-d. Please note, the substitution of parts in place of the originally certified parts may impact intrinsic safety. Please contact your safety department for more information. 
If the charger you select does not stop charging the battery pack when it is fully charged, you will need to choose a different brand of charger. Your battery manufacturer should be able to recommend a suitable option for you.

Please contact  with any questions or concerns.