On Aug 4, 2023, at 2:26 PM, Tim W4FX <w4fx@...> wrote:

?Here's a question. I'll qualify this by noting that I'm an OG computer nerd with 4 decades in the business, but fairly new and unschooled as an electronics maker. It's the hazards of being a software guy.

That being said, would it be possible to use three 3.7V lithium polymer batteries in series? Say, something about 3mm thick each, which isn't hard to find. Or would you have to add a separate BMS to charge it, since it's an assembly instead of a single pack? I'm pretty sure that would definitely be the case for LiFePO4, but I don't know about the chemistry for LiPoly.

Since our only other solutions seem to be stuck in Europe, I'm just grabbing at straws at this point.