You can always have some spare batteries to replace the dead ones, but Chris Winter shared a pretty cool external battery hack that uses a 10,000mAh which is roughly 9 times the capacity.
Now, I am not sure if you can actually call off the shelf products a hack, but between the fast that you get so much more usage time and the clever way Chris mounts the battery with Velcro, I thought it is worth sharing.
The trick is to use a Camera Power Coupler DC Dummy Battery Pack by Lanparte and to connect it to an external battery. They come in both an LP-EP6 (for 5D3 5D2 7D 60D) and LP-EP8 (for 550D 600D 650D) flavors for about $30-$40 and replace the Canon battery you usually place in the battery chamber.
To complete the setup, Chris uses a 10,000mAh battery that has an external DC output of 9V which is close enough to the operational voltage of 7.4 that the camera needs.
We shared a similar hack before, only for this one you don’t actually need a sacrificial battery.