In the camera, I’m thinking that they heat up. The Canon is current hungry, which is why it does not play well with other chemistries. So the high draw heats up the battery and makes it work more optimally in the cold.
Heat from voltage conversion is one of the limitations of these cells.
People should be aware of the pretty serious limitations, and a few advantages, of the 1.5v lithium AA/AAA. The ‘generalizations’ are applicable to the entire class.
A BIG issue, is quality; quality of the lithium cell inside, quality of the electronics, and quality of the assembly. We all know there is a HUGE difference between cheap Li-on or NiMh cells. Same with the 1.5v lithium AA/AAA.
I’ve been using Tenavolt 1.5v lithium AA for over a year. Purchased on a great deal, I’m pretty satisfied. They aren’t Eneloops, but they fill a couple niche uses pretty well. For full price, they simply are not worth it unless you have a serious need for 1.5v continuous output.
I….just…. received and am at this moment testing out [4x High-capacity JWWYJ 1.5V USB-C Lithium Ion AA Batteries] that I got from Amazon, only because they were $12 and I was curious.
I can tell you already they are not as good as the Tenavolt; current capability is about 0.5A less, and capacity seems to be around 200mAh less (~1400mAh). They do hold 1.48v under a 1A load right up to shutdown. Tenavolt will handle 1.5A draw fine, and does not do well beyond that.