On Sun, 19 Dec 2004 19:09:49 +0000 (UTC), tango4 wrote:

"WilLiscomb" wrote in message
...
voltage regulator
williscomb



Hmmmm

Build a 'better' battery so that you can dump power into a voltage
regulator. Cute.

Actually the forward biased semiconductor junction in the form of a diode is
a much easier way to do things.

Ian

Only problem is that the voltage drop is also present at the
end-of-charge point, thus losing the last 0.7v of possible battery
voltage before things start working strangely.
If you use a well designed switching regulator which can boost as well
as buck, the voltage supplied to the instruments can be maintained in
the ideal range until the battery is almost completely flat, and at an
average efficiency of about 80%. AFAIK, complete discharge is not
harmful to NiCd, Lithium types etc. It is harmful to lead acid
batteries.
Cheers, John G.