EOS body battery drain on long exposures

From Chuck Westfall of Canon
Via Willem-Jan Markerink

Here is some data on battery drain during long exposures:

Camera Body Power Source Maximum exposure time

EOS 600 series 2CR5 Unlimited*

EOS 700/750/850 2CR5 16 Hours

EOS 1 2CR5 60 Hours (50 hours with PDB E1/alkaline)

EOS-1N/RS 2CR5 60 Hours (50 hours with PDB E1/alkaline)

EOS 5/A2/A2E 2CR5 6 Hours

EOS 10/10s 2CR5 Unlimited*

EOS 50/Elan II 2CR5 15 Hours

EOS 100/Elan 2CR5 6 Hours

EOS 500N/500 CR123A x 2 6 Hours

EOS Rebel G/XS CR123A x 2 6 Hours

EOS 1000/1000F 2CR5 6 Hours

EOS Rebel/Rebel S 2CR5 6 Hours

EOS 1000N/1000FN 2CR5 6 Hours

EOS Rebel II/S II 2CR5 6 Hours

EF-M 2CR5 6 Hours

EOS 5000/888 CR123A x 2 6 Hours

[*] The EOS 600 series and EOS 10/10s use a shutter release mechanism that only draws power to open or close the shutter curtains. No power is consumed when the shutter is at rest, whether it is open or closed. (This can be proved by disconnecting the battery during a long exposure.) Consequently, these models are better suited than other EOS cameras for extended time exposures such as those required for astrophotography.

It should be noted that the figures quoted are presumably accurate for operation at room temperature only. I would expect poorer performance in cold temperatures. Also, there is very little data available for performance with alternate power supplies. For example, we have no idea how the performance of the EOS-1/1N/RS series would be affected by the use of Ni-Cd Pack E1 or AA-size lithium cells in Power Drive Booster E1, or with BP-E1. Presumably, Ni-Cd would perform worse than alkaline at room temperature, but better in cold conditions. Similarly, there's no information available on bulb exposure performance for the EOS 5/A2/A2E or EOS 50/Elan II series with their respective D-cell power packs, though these accessories increase shooting capacity for regular photography up to 700% compared to the 2CR5.