12 volt shunt

[T1 Terry]

The shunt must match the gauge as Bruce has said. You can just buy a shunt and a very finely calibrated volt meter and set your own markings on the gauge. you would need to accurately measure how much current was flowing through the shunt and then mark that point of needle deflection as that amp draw. Much easier to buy the digital units that are already set up to just work.
The next issue is the quality of the shunt being used, a $10 shunt will not be very accurate so you will need one that measures the lowest current value to minimise the error factor. 5% of 20 amps is only plus or minus 0.4amps, but 5% of 200amps is plus or minus 4 amps and the information would then be useless if 1 amp accuracy is what you require. When it comes to any sort of measuring equipment, price often reflects accuracy, if give or take half a brick is accurate enough for you then a $10 shunt will do all you want, if you want a very accurate device the Victron BMV600s is around $200 or less at the moment and their accuracy is brilliant along with their programmability, the only ones accurate enough to use with lithium batteries, the others suffer accumulated errors and become useless for accurate SOC measurement after only a week and need to be regularly reset.

[BernieQ2]

Your getting to technical Terry, I don't need any accuracy just like to watch the needle jump when the pump or fridge comes on.
That tells me its working that's all so simple.
And I will be buying a matched pair [shunt/gauge] when I get around to buying one.
Main reason for analogue is I can cut a round hole no good at squares, and where its to located wont allow me any stuff ups.
Back to the main question what size shunt and gauge for my small power use.
Bernie.

[supersparky]

Bernie, Have a look at these http://www.ebay.com.au/sch/i.html/_W0QQ ... unt&crdt=0 from evilbay. Not very expensive. You probably don't need much bigger than 50amp by the sound of things. Are you going to have solar?
Bruce, you are correct. I love steam trains. And bagpipes.

[BernieQ2]

G'day David, yep 50's probably about right, and yes I have 600 watts on the roof.
Bernie.

[Cuppa]

Bagpipes! You haven’t been associating with MrsTea have You Dave?!!?

[supersparky]

Bagpipes! You haven’t been associating with MrsTea have You Dave?!!?

I do still have the family bagpipes. Well over 100 years old. I just wish I could play them properly. Just another thing that I didn't learn when I was young.

Bernie, I have just realised that I didn't include a link for the evilbay shunts. So I edited my post above.

[jon_d]

Bernie,

Sorry for the delay.

This is what you need, the little panel meter is wired across the shunt. And display the current being drawn.

http://www.ebay.com.au/itm/Current-Pane ... 1e89e51cc2


jd