the opus will shut down before the battery is drained...
It should, however it may not shut down soon enough in some cases. My Opus 150W has drained my battery a few times. It did shut down during low voltage, unfortunately by this time there wasn't enough juice left to crank.
Plus, the 5VSB rail is always on leeching power. Depending on the power used by your USB devices, you may want to disable the rail when the computer shuts down (see the relay mod post for the 150W or set the jumper on the 90W).
I killed my first battery because of a combination of the above.
hmn...you could set a momentary switch that sends a signal to the opus to turn on, and set the jumper on the opus to 30 or 60 minutes so it automatically shuts down after this time unless you hit the button again or actually start the car
You need a single poll, double throw switch (SPDT). Mechanically it's like an on-off switch, but it's real use is as an on-on switch. In one possition you provide one path for voltage, and in the other possition you provide another path. You can also call it a changeover switch.
I used a single poll, double throw switch (SPDT) for my ACC. I attached the ACC-IN wire for the power supply to the "COM" of the switch. Then I connected ignition power/ACC power from the car to the A terminal of the switch, and a live 12 volts to terminal B. When the switch is in the A possition, it closes the connection for ignition power from the car. When the switch is in possition B, it closes the live 12 volts to the ACC-in of the power supply.
- Connect ACC-IN wire from OPUS to "COM" of switch.
- Connect ignition power (ACC power) to terminal A on the switch
- Connect live 12 volts to terminal B on the switch
When you put the switch in possition B you can turn off the car and run into the store for five minutes, and the PC will stay powered on. This is because possition B sends 12 volts to the ACC-In of the power supply and tricks it into thinking the key is in the ON possition. You can also use this trick to turn the PC on as well (be aware of the 4 second power on delay). The trick is to not forget to change the switch back to possition A. If you forget, the PC will stay powered on while you sleep at night and drain your battery.