On Thu, 14 Jan 2021 11:04:55 +0000
The Natural Philosopher  wrote:

> On 14/01/2021 10:18, Ahem A Rivet's Shot wrote:
> > On 13 Jan 2021 23:37:18 +0000 (GMT)
> > Theo  wrote:
> >
> >> Joe  wrote:
> >>> Lithium cells have a linear-ish discharge curve, from 4.2V down to
> >>> around 3V. Any sensibly designed lithium battery will cut off its
> >>> output at the chosen lower bound, because if it completely discharges,
> >>> it's dead forever. Not a 'steep' decline, a 'fall off the wall'
> >>> decline.
> >>>
> >>> It's a good idea to have some independent means of anticipating this
> >>> point.
> >>
> >> But lithium ion cells don't work for this application.  We need 5V.
> >> One cell is too little, two cells is too much.
> >
> >  One cell and a DC-DC converter to give you a regulated supply,
> > monitor the cell so you can shut down (well) before there's too little
> > to run the converter.
> >
> It's slightly simpler and more efficient to use a step down from two
> cells.

 It's only simpler if you look at what's on the converter board :)

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