Are you using the same apps for all the ROMs?  Earlier I suspected some app syncing during standby mode will cause SOD, but now I'm not sure anymore.
The screen is also smaller.  Gingerbread promised but until now no news from LG, almost a year since the phone was released already
After you charge to 100, you need to wait some more until you hear a notification sound and a 100% appears on the left of the notification bar.

u charge while u switch on ur SGA?

if yes, is normal as the charger need pump higher voltage into battery and SGA assumed the power is from battery...
example i plug SGA for data transfer for while, before plug about 30%, after file transfer about 60%, just plugged about 3min only, quite impossible charge so much within the short period... later after 1-2 min my battery widget drop to 35%...

for more accuracy, better switch off ur SGA and see the big battery indicator... once the big battery indicator show "100%", u will around 97%-100% after u switch on your hp...