Jinx,

On Thu, 14 Sep 2006 16:47:51 +1200, Jinx wrote:

> > > If you've power to spare, a switcher perhaps. Cuts down
> > > on heat production from wasted drop
> > 
> > ... or produces a higher voltage from a single cell.
> 
> Good point. Especially if, say, you've got a mixed low-voltage
> and high-voltage circuit (eg PIC driving white LEDs or relay)
> and need or can have only small batteries

I read an article many years ago by someone proposing that the best portable power supply is a single large rechargeable cell and a boost PSU to 
produce whatever voltage you want.  The rationale was that by having more than one cell you never get the best performance, only that of the 
worst cell, and recharging can never balance them properly without leaving at least one under- or over-charged.  And when discharging you can 
never know when one cell gets to its "don't go below" voltage, so you either risk damaging some cells by over-discharge, or stop early and reduce 
the usable capacity.  With a single cell you can always treat it properly.

Since you can now get 9Ah NiMh D cells, it's certainly an interesting point!

Cheers,


Howard Winter
St.Albans, England


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