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RE: Current sensing, etc

Induction type current probes, clamp on (Amprobe brand) or otherwise, only
work on AC.  There are now clamp on hall effect AC/DC curent sensors.  
are  generally expensive and subject to zero drift on DC measurements.

-Steve Naugler
-e mail address:  snaugler rodel com

> ----------
> From:         vic garza[SMTP:vtr-garza worldnet att net]
> Sent:         Saturday, January 02, 1999 10:41 PM
> To:   David Roden
> Cc:   elec-trak cosmos5 phy tufts edu
> Subject:      Re: Current sensing, etc
> At 09:38 PM 1/2/99 -0500, David wrote:
> >"Max Hall" <maxo iname com> writes:
> >
> >> The
> >> problem is, how do you get the resistance to be nice and small, and 
> >> yet
> >> stable, so you can measure current without pissing away power? 
> >
> >You buy a high current shunt.  The EV parts dealers (Electro 
> >Automotive, 
> >KTA Services, and so on) sell them, and you might be able to find them 
> >at
> >a local industrial vehicle shop.
> Military surplus is much cheaper when available, check Fair Radio
> http://alpha.wcoil.com/~fairadio/ or Burdens 1-800-488-3407 from time to
> time. There are also induction type ampmeters which you don't have to 
> hook
> into the circuit(work by placing a set of jaws around battery cable) but 
> I
> don't think they are quite as accurate...
> >Someone may disagree with me, but I'm of the opinion that most domestic 
> >garages are large enough (and leaky enough) that hydrogen buildup is 
> >not 
> >really a concern, given the number of batteries and the rate of charge 
> >an
> >ET uses.
> Unless the batteries have some type of solid cover (even loose fitting)
> directly over them which concentrates the hydrogen there's usually no
> hazard
> in my experience.
> >This is one of the older model snow throwers.  Maybe I'm expecting too 
> >much of a single stage snow thrower (though it looks pretty potent).  
> >Or 
> >maybe not.  Anybody have any idea what I might be doing wrong here?
> Low temp have devastating effects on lead batteries. You might want to
> check
> the voltage under load to see if holds above 11V per battery with the 
> snow
> thrower and tractor on especially if batteries are old. JC Whitney offers
> a
> high current series-parallel switch for automobile starting which
> effectively doubles cranking voltage so that cold weather starts in IC
> autos
> are possible. You might have to devise some method to boost the under 
> load
> voltage...
> --Vic