John Giddy writes:

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%.

With carefull design and construction, you can get over 95% efficient
converters running from a 12v source.

AFAIK, complete discharge is not harmful to NiCd, Lithium types
etc. It is harmful to lead acid batteries.

Full dischare of a NiCd *battery* is bad news, it is OK to fully
discharge a single cell on its own though. Lead acids can be run
totally flat, but must be put on charge imediatly or they
`sulphate'. Don't know about the various Li batteries.

--
Paul Repacholi 1 Crescent Rd.,
+61 (08) 9257-1001 Kalamunda.
West Australia 6076
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