I have a G gauge Challenger with a replacement board that acts up and usually starts in conventional.
http://mthtrains.com/content/70-3004-1
Ps2 3 volt blue battery. Replacement board installed at factory service. Board and battery in boiler. Long charging lead runs to front door. Battery leads go into some remote board right next to battery.
Just put in BCR2 2 days ago.
Just tested old battery and it reads 2.2 volts after laying on the work bench for two days.
Engine will go through shut down sequence when track power is killed after coming up in conventional mode.
Bought external charger two months ago and when used overnight, the engine behave as normal.