Hm... just found this post, my 05 OBXT seems to be having the same problem... i drove it up to canada the other day, got back, and forgot to turn of the map lights, no big deal.. so i come back a few days later, and jump it, and let it charge for a while. the next day i came back and it was dead again... so i jump it again, then drive around (~9-10 miles) go inside for about 2 hours... go to turn it on again.. and there's power, but not enough to crank the engine (click click click click click....)
so... i just jumped it again, and drove it around town, left it running when i went shopping etc.. (on for about 2 hours) i guess i'll see how that turns out..
when the car is running, across the battery terminals reads ~14.5V, with the car off it's ~12.5V
i pulled the + terminal, and checked the amperage and it was 0.100mA... seems a bit high for a little blinking security light, aye?
i also tried pulling some fuses and checking the amperage, i pulled out the 'lighting' fuse in the engine box... nothing else looked like it would do much.. i'll try more later if it continues to be a little whore...
any ideas? maybe the map light browned out when i left it on the other night?.. doesn't really make sense.. because it still works...
the battery is an optima red top.. so it should have no problems..