Yes the MOTU is FW powered, but it draws down the computer pretty quick. I'm running a MacBookPro and it gets pretty toasty. The extra batteries I have are from a Dell. Also, the Motu can run w/o a computer going direct digital out. I'm thinking about leaving the computer at home and recording to a MT2496 or a JB3.
What I'm curious about is if anyone has experience with these things. They're "smart" batteries with seven electrodes. I can only measure 5V on one of the pins. When I plug in the power adapter into the computer there are two pins (in the computer) that measure 5V. The computer's charger puts out 20V and the battery is rated at 11.1V. I think some of the pins on the battery need to either have a voltage or a resistance put across to "turn on" the 11.1V, but that's only a guess. Also, I'd like to be able to recharge these without the computer.
Any ideas?