Installing a Garmin

[cdneh]

Hi
I just purchased a garmin 660 and was told by a fellow rider to hook it directly to the battery. He said if you connect it to any accessory connectors the garmin will eventually fail, something to do with the charge when starting the motorcycle. Since this is my first GPS I am not sure if this is necessary. Any suggestions on the correct way to hook it up is appreciated. Thank you.