I've also been having the same battery issues you have.
The appeared after the latest ROM/firmware update.
The call quality was improved, but the battery was much much worse than before.
My guess is that it might have something to do with Mango, but Mango might be a month away, so I am returning to the old installation.
Can report back on weather or not the battery is back to normal.
Optimus 7 had a good battery prior to the ROM update, would last at least one day with normal settings, push email and so on.