Exposure and Star Trails

[astroNikon]

what kind of intervalometer do you have ?

fyi, I don't use an external one. My Nikon has it built in so I can't really compare. Though my wireless trigger battery has lasted a couple years so far.

Generally for most models you have to use Magic Lantern for a built in Canon intervalometer
Magic Lantern | Home

Or use an external intervalometer. Which uses it's own battery ... which is what is draining quickly for the OP.
So I assume OP is using some brand external intervalometer ...