It seems the BCM was causing problems. From page 6 of
BigEd wrote:
Relevant photos and diagram in
this PDFQuote:
It is believed that electrical noise, as a result of insufficient filtering, being generated from the “as delivered” BCM is responsible for the undercharge condition. Ground testing with an upgraded BCM has successfully demonstrated a full charge of the EMU battery. In April 2002, 2 upgraded BCMs were installed in the Joint Airlock, replacing 2 older configuration BCMs. An in-flight experiment is scheduled for late May 2002 to determine if the upgrades made to the BCMs will solve this undercharge condition.
So, is 6502 still at the space station? This
2010 document notes an award to a team that replaced the "anomalous BCM".
Quote:
Battery Charger Module (BCM) Team of Oceaneering Space Systems - Dedicated effort and exceptional technical expertise enabling the Space Station Program to replace anomalous on-orbit BCM units, and provide future ISS crews with reliable battery charging and discharging capabilities for years to come.
Perhaps NASA works slowly and this is an award for the 2002 work. Or maybe there is a new design on board now.