If your laptop AC/DC adapter outputs 18, 19, or 20V, you may want to get a Carnetix P1900. This board has a delayed on remote line to turn on the amps after the computer has started booting. I'm not sure if you will even have to worry about that with optical though. You can hook it up to the laptop's power switch to alleviate the problem with the computer draining the battery. The computer should not stay on when you are not in the car for long periods of time. A cap is not a battery. It will not help power your computer overnight. It is meant for slow charging and quick output. For the extra money (over the inverter), the P1900 will be well worth it. It will handle startup/shutdown, prevent thump when the computer gets power and regulate the power to the laptop efficiently (much more so than an inverter).