RussellMc wrote:
>> ...  what is being proposed here in that with 4 AAs
>> there is no need for the boost converter, ...
>
> For some values of "no need".
> Lithium Ion cells with have ~=3D 4.2V terminal voltage.

The OP has mentioned several times that he is using a specific model of NiM=
H
cells.  4 of those in series does work out just about right over the valid
range of USB voltages.


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