Silent Knight 5820 int. power problem

I work for a group of colleges and we have over 100 silent knight panels, mostly 5820’s with some IFP 1000’s. During our testing over the last year we have discovered a problem with the internal power supplies of both these panels. All of the affected panels are version 9 from 2009 and early 2010. Over time the power supply output voltage decreases until it won’t charge the batteries or, if the batteries are disconnected there is not enough power keep the system running. We have found about 8 panels so far which is a high percentage of failing panels. I wonder has anyone else had problems with these panels.