> > and don't work at all with certain improvised battery arrangements (ie
> > NiCd or NiMH cells rescued from a damaged pack, which tend to be flat
> > on both ends.)
I don't suggest using cells "rescued" from a battery pack in this way
either, but...

>   As extension to my comments on corrosion, I'm dismayed to think you
> would even *consider* using Ni-Cd cells in a battery holder fitting.
> It's not by accident that products intended to *work* using Ni-Cds
> always use a somewhat expensive sealed battery module with welded tags on the
> cells.  At least when they fail, you haven't crapped all over the
> innards of the appliance!
... Clearly, many NiCd cells are packaged to be identical size to
"Alkaline" (Zinc/Manganese Dioxide) batteries.  The manufacturers
*intend* that they can be used in place of Alkaline batteries and
removed for recharging.  They have the button contacts on the
positive end to reach into a polarized holder.

And get get back on the off topic: I vote for molded-in ribs which
don't let the flat negative terminal make contact in the wrong
direction.  It ain't perfect, but it usually works well.

For "9 volt" snap contact batteries, you *Have to* have reverse
polarity protection.  Usually, you can afford one Shottkey diode
drop.  I wonder if any linear or buck-switcher regulators have
inherent (low loss) reverse protection built in?  It seems like a
bipolar LDO regulator would prevent the load from drawing reverse
current, but the regulator might fail.  Has anyone here done a
survey of the common regulators lately and found this out?

------------
Barry King, KA1NLH
Engineering Manager
NRG Systems "Measuring the Wind's Energy"
Hinesburg, Vermont, USA
barry@nrgsystems.com
"The witty saying has been deleted due to limited EPROM space"