Intervalometer and battery life?

[Omnitographer]

I'm looking to shoot a time-lapse friday and I was curious to find out, without adding a ton of useless clicks to my camera's shutter, about how long the battery lasts on a 60D, for those who have done this. I'd also like to know if the frame rate changes the shooting duration, say if I shoot with 2 second delay and get 3 hours, does shooting with a 6 second delay get 9 hours, or any increase at all?

Thank you.

[screamer]

Hi, i have the 60d and i'm doing often timelapses. My battery last a lot (many hours). And really never done a so long timelapse (my longest one was 4 hours, with 30second shots).
For the other question i'm not shure to understand what you say. But the delay is the delay between a shot and the next one. But the real interval between a shot is that time plus the exposition time. I mean, if your frames has 30s time, and your delay is 2s, so you have a real interval of 32seconds between a shot and the other.
I suggest, especially if you are capturing long exposures (for example stars or something like that) to use no delay between the photos (the voice on the ml menu is: "take pics like a crazy"). So you have the minimum, mechanical time between a shot and the other, and you cover all the time of the scene without intervals
but of course, it depends on your needs