PowerStream charger connects to E+ battery electronics which contain not one , not two , not three but 6 thermistors. Every 5-cell module has thermistor on small board called sense board, those thermistors are connected in series/paraller combination of around 15-18ohms.
I am sure any NMH 30-cell chemistry charger will work on our Epluses , first thing to check is thermistor requirement for such charger is.
Most NMH chargers require 10 -15Kohms thermistor as standard.