Re: Current sensing, etc

[vic garza <vtr-garza worldnet att net>]

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