Tuesday, November 06, 2012


I just paid in US dollars to buy something from China.  What is the world coming to? It’s all Piston Broke’s fault.  Chatting to them last week convinced me that I ought to have a measure of the current produced by Herbie’s solar panel principally so I can aim it to get best advantage from the sun.  My solar panel controller gives no information other than a red LED that lights up when the panel is doing anything at all. So to get a reading of amps  I need an ammeter to measure and a shunt through which to pass the current.  That means the ammeter isn’t really an ammeter at all but a voltmeter measuring the voltage across the tiny resistance of the shunt and translating it into a display of amps.

This all sounds very complicated but it isn’t.  And the kit is cheap.  $20 US including postage from China.  Why China?  That’s what I’m wondering really, but looking on Ebay, that’s the only place these things come from.  Why no-one over here sells a 10A shunt and calibrated ammeter I don’t know.

The shunt, which is just a metal bar like this:

will go in the line between the solar controller and the negative domestic battery terminal, and the ammeter which looks like this:

will connect to either end of the shunt.  Bob’s yer uncle.  I suppose I will have to make a little box to install the meter in.  It’ll need a little battery in there too to power the ammeter. I’m thinking I might combine it with our Smartgauge all in one box.  Then we’ll no doubt turn into amp anoraks, or is that amporaks.  I’m already amused by how Kath has turned into a battery capacity anorak.  She can’t walk past the Smartgauge without pressing the button to get a reading.

1 comment:

Halfie said...

Annoyingly, I'd composed a longish comment, which I thought I'd published, and yet it isn't here.