> Here's the application: I'm in the early stages of construction 
>of a mobile robot powered by two 14.4VDC motors. I want to 
>determine power consumption under several situations so I can 
>optimally dimension the battery supply for my robot. The robot 
>is going to navigate over rough terrain, so load can change from 
>time to time (hill climbing, rock crawling, etc), and I'd like to 
>create a logger that would record sampled electrical current. Is
> that an easy thing to do?

You can do this magnetically.  Take a look at NVE's giant
magnetoresistive sensors.  They have at least one, probably
more, app notes about hooking those puppies up to measure
the current flowing in a trace by the radiated magnetic field.

It is *certainly* going to be much mathier than just running the
current through a resistor, but will waste much less power,
run much cooler, is *completely* passive, and the knowledge
to be gained from doing it is probably more valuable than
using a shunt resistor.

Mike H.

PS- Here's an appnote on using them...http://tinyurl.com/4yocm
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