ammeter and voltmeter needed

williamwright · 2020-09-05T16:52:12+00:00

I've been ages searching and I can't find what I want, though it sounds so simple. It's a digital ammeter/voltmeter combination. The max voltage to be read is 16VDC; the max amps to be read is 20A. The supply voltage is nominally 12VDC. It would be perfectly OK for the voltmeter and ammeter to be separate units.I found a product priced at around £20, which seems a bit cheap to me, but delivery is 20th - 29th Oct, and it only reads up to 15A 15A would be OK at a pinch, but I can't wait until 20th Oct.I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so. I do need centre zero.I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and I will need to see a confirmation of that sort of low current use/charge.I don't want a hall effect device; I want something with a shunt.I've looked all over. I must be looking in the wrong places. Can anyone who is conversant with such things and knows the suppliers help?Bill

Sep 05, 2020 Last reply: 6 years ago 24 Replies

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Harry Bloomfield, Esq. 6 years ago

Dave Plowman (News) used his keyboard to write :

On a car, you can put your meter end to end across the main battery thick cable, using that as the shunt. You can calibrate the meter using a resistance in series with the meter.

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The Natural Philosopher 6 years ago

Not exactly corrected for temperature and not ideal unless you do it AFTER the starter motor takeoff

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Dave Plowman (News 6 years ago

Maplin did just such a kit many years ago. Measuring the voltage drop across the main ground - battery to chassis. It had several modes - but one was driving a tri-colour LED. Red for discharge, green for charge, amber for the load just balanced.

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