HP41 Battery idea Lipo

[Harald]

(05-23-2023 05:11 PM)Diego Diaz Wrote:  Working on a solution for the third: the BAT indicator. It requires some sort of "emulation" of the discharge curve of the alkalines, and I think it can be done by tweaking a bit the DC-DC converter with some 'amplified negative feedback loop' (just an idea for now), and yes I know it may sound kinda contradictory since it's a stet-"up" converter... :-D

I think all you need to do is detect low voltage on the lipo, and when you detect it set the DC/DC converter to an output voltage that makes the 41 turn on the low voltage indiction.
So basically just a comparator that detects when the LiPo drops below a threshold and then tweaks the DC/DC converter feedback path.