Hi all, love this forum and finally need some advice. Bought an 8 dollar volt/amp metre from the interwebby thingy and downloaded the wiring diagram which makes very little sense in English. It has two fine red and black wires and three heavier gauge wires coming from a different area, so all up five wires.
I realise I don't require a shunt so the yellow wire is irrelevant. As the photos show, it reads volts when both reds and either black wire is attached so I need to know which black and where do I wire it to, to get the amps measured? I also want to wire it to a spare on off toggle switch and I cant quite get my head around it all, so if someone can explain it for a dummy I would love to hear from you.
Cant seem to download any photos, so really proves Im a dummy

Sure, you supply plenty of info, but even when you know which one goes where,
It's just a start of you trouble.

- a current flow is measured in minus section (common),
there are many commons around the boats,
they all have to go through the shunt.

- inbuilt shut is very fragile, any overload or power surge will blow the shunt,
you have blackout, anything connected through measured section is dead/open circuit.

- in build shunts are typically for low current and maximum load must be calculated
and carefully selected.

It's just rough guide, the rest is easy.

Your wiring - thick black minus power source / battery minus /
red wires both connected together / battery plus /
yellow wire connected to all returns /minus / sections under test
thin black Not used (Only if external power is used )

Try this diagram:

assets.bluesea.com/files/resources/application_briefs/DC_DigitalMeter_WD.pdf

But again, it shows a shunt that is placed directly between the battery -ve. and then to the distribution bus/loads. All loads are connected after the shunt so they can be measured by the meter. Nothing else is connected directly to the battery -ve except the shunt. You will then be measuring the whole load/charge on your system, which I presume is what you want to do.

I would not attempt to connect it up any other way.

Search a few of the popular battery monitor manufacturers and you will see they all wire up the same way with an external shunt.

http://www.nasamarine.com/images/file/BM1+-BM2+.pdf

www.xantrex.com/documents/Discontinued-Products/Link10(445-0195-01-01_rev-A).pdf