For my wild life camera, I want a small cell that can provide 0.5W for 8 hours or more. It doesn't seems rechargeable lithium ion batteries have that energy density. I don't mind if the cell is non-rechargeable, so I've considered the lithium coin cells and zinc-air batteries.
But it seems the internal resistance on those are terrible: For a CR2477, I estimate the resistance at 910 ohms! Energy density = 2.96 MJ/L
For a 675 hearing aid cell, I estimate 34.7 ohms. Energy density = 6 MJ/L !
So if I use those, there's no way I can draw 0.5W, if at all, without having all the energy consumed by IR? (is IR the only factor causing lower capacity?)
Is this a fundamental limitation to those battery chemistries or can someone point me to cells that allow higher current draw?
According to Wikipedia's energy density page, it claims there are non-rechargeable lithium batteries with an energy density of 4.32 MJ/L. That would be awesome, but where do I find them? (I'm only seeing 2.96 MJ/L for a CR2477 coin cell).