Originally Posted by Vicks
ACC2 is switched and ACC1 is powered all the time irrespective of the ignition key/switch position. If you have an electrical accessory (heated grip/some other stuff/GPS) connected to ACC1 and leave it on after you ride/switch off the engine, the device will continue to be powered unless you turn it off yourself, draining the battery.
Also, the ACC1 and the clock share the same fuse. So if you fook up something on the ACC1 while connecting a device or something and create a short circuit etc, the fuse will blow. Even if you shift your device to ACC2, the clock on your display won't work bcos of the blown fuse. You can use one of the spare fuses provided. If you run out of spare fuses, and if you have a 990S/R without ABS, you can use the ABS fuse (which is also 10A).
And I would add: When you take the headlight off the bike, you will find pre-wired and labled ACC1 and ACC2 spade connectors for hooking up accessories.
Remember: If you hook something to ACC1 and leave it on.. you will kill your battery (refer to jump starting procedure