Richard J Kinch wrote:

Jeff writes:


But the spec sheet says "Average current consumption for 12 VDC
systems over 24-hour period." This is the number of interest to most
boaters, and the proper measure is Amp-Hours.



No it isn't. Current is measured in amps. Amp-hours are not a
measure of current. Nothing could be simpler, and nothing more can
really be debated about it. This is not an oversight, it shows the
author is a fraud or a fool.

Yes current is measured in amps. But to be useful you need another
measurement, time. That gives amp hours. Battery capacity is rated in
amp hours, usually at a 20 amp rate. If I want to know what size
batteries I need to supply my house load I measure the current used by
each device, i.e. lights, fans, reffer, etc and determine the
approximate time used by each device and compute total amp hours load
over a 12 or 24 hour period. Multiply the amp hour load by two and use
that size battery. So while you are correct that the measurement of
current is amps, if a manufacturer list a spec of 54 amp hours usage
in 24 hours it tells me a lot more than just 4 amps compressor draw.
krj

Ya know, this thread keeps gettin sillier and sillier. Amp-hours, if
anyone cares to look it up instead of just flappin, is a measurement of
current. And I defy anyone, including Mr. Kinch, to find a way for
current to flow without time. If current was without time, it could not
possibly *be* current. It would then be reduced to "...potential for
current to flow, which when flowing would be measured in amp-hours..."
Current is a verb, it defines an action. Without the action, there's no
flow. Without the flow there's no "amps", which is always measured
against a unit of time - the convention being hours (notice I said
'convention'- you could use any time measurement, days, U-seconds,
etc.). It cannot be measured without time - ever. Therefore, "amps" by
itself, does not describe anything. You could say there is a measurement
of an *instantaneous current* but that would still be just a snapshot of
the presently measured current-against-time. Amp-hours is and has been
the correct term because a "1 amp" device is defined by convention as a
device that passes a current of 1 amp during the course of an hour. The
term "1 amp" is simply a contraction for "device that passes 1 amp of
current during the period of one hour" Now, isn't that a mouthful?
Jeesh! The engineers and tech's of old used to actually *say*
"amp-hours" when describing current, and all my old electronics
textbooks use that term exclusively.

So if Mr. Kinch wants to call all my electronics professors frauds or
fools, so be it. But then I'll challenge him to come over and put his
instruments where his mouth is and show us all how he manages to measure
"amps" without time for the electrons to flow.

Or was that holes flowing... hmmm...