I buy 7-9ah sla batteries and make a wire that goes to a plug. This plugs into the port on the tactacam 2.0 i have. Seems to work great when i hunt on my own land. If a battery dies i just recharge it and its good again for a long time.
Over the longer run this is the cheapeast option ive found, you just have to wire up to the big battery.
This works for my cell cams and non-cell cams, fyi.
I've had good luck with the Amazon batteries in both cell cams and non-cell cams. Not sure if they are as good as energizer or duracell but they seem to be pretty similar.