EOS Rebel T3i battery life for time lapse video

[spiceman]

I want to shoot a series of shots for a time lapse video. I'll be shooting at 1/125 @ f8.0, ISO 200, in LIVE mode, with the interval of 10 seconds. Can someone give me an approximation of how long a freshly charged battery would last? 

[rs-eos]

The user manual may outline estimated battery life when using live view.  Also, what lens will you be using?  And, what will be your setup?  i.e. will the camera be on a tripod, and you'll acquire focus on your subject, then set the lens to manual focus?  Or, during the time lapse, will the lens be re-focusing?  This latter scenario will consume more power.

[spiceman]

I will be using Tamron 18-270.  Focus will manual and yes, with tripod. Thanks for reminding me of the manual. Unfortunately, it says only 200 images which is well short of what I would expect to shoot in about 2 1/2 hours (talking about the annular eclipse next month). I may have to forgo Live View.

[rs-eos]

Unless you need live view along the way, best to not use for this scenario.

About the only other thing I can think of is that if you have spare batteries, and the battery compartment would be easily accessible while the camera is on the tripod, you could attempt swapping.  Tricky though and you'd have less than 10 seconds to pull that off.

[spiceman]

Yes, those are the conclusions I've reached. I figure if I change the battery right at maximum annularity, loosing a frame would probably not impact the final product much, if at all. Thanks for your feedback.

[normadel]

Look at your camera manual. The System Map shows an AC Adapter (aftermarkets available also) to power the camera for long durations. I have AC adapters for all my Canons....Rebel T1i, 50D, 60D, 6D and 7D.

[spiceman]

Thanks for that info. Since, in most situation, I will not have access to AC power, can you recommend something to use in the field? A remote battery pack of some kind?

[normadel]

There have been posts here concerning battery pack power units for cameras and whether they work. I don't have familiarity with them.