Need a wiring guru

[ChookD2]

In the rear of my D2 connected to a second battery I have a Volt/Amp meter, a 2 socket USB and 2 x Cig Sockets. I had one cig socket with neg wired gang style to centre post on meter and showed amps when under load from fridge. So in my wisdom :wacko: I assumed that a bus bar would connect all sockets to the amp meter and show load from all. Doesn't seem to work like that though.

Image 1 shows bus bar.
Image 2 shows sockets and meter with phone and light connected, no load shown.
Image 3 is rear of sockets.

Have moved a few wires around but just can't get any load to show. A phone and an LED strip light (1.2m) wouldn't draw much current but should be something. I believe the meter has in-built shunt to 10A.

Any suggestions or indication where I've gone wrong?

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[Ferret]

It's not entirely clear from your photos but the ammeter will not show any load unless it is wired to be in series with all the sockets which could potentially draw current.

[ChookD2]

It's not entirely clear from your photos but the ammeter will not show any load unless it is wired to be in series with all the sockets which could potentially draw current.

Doesn't the bus bar achieve this on the negative side?

A bit more info. All the +ve from each socket and the meter run to a fuse box and individual fuses. Fuse box connected to +ve on battery.
Battery -ve runs as shown to bus bar and then to each socket and ammeter connection (centre post of only socket with 3).

Do I need to +ve bus bar as well?

Do I need to run each -ve from each socket to the ammeter?

I'm confused, have looked at couple of wiring diagrams on the net but most are for boats or just the meter itself to a battery.

Looks like this:

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[theelms66]

Is there any markings on the back of the ammeter. What is the rating of the meter?

[ChookD2]

Is there any markings on the back of the ammeter. What is the rating of the meter?

As far as I am aware it is 10A. Top pin is marked + bottom pin is marked - centre pin has a small hole to one side and CE to the other. It has a built in shunt, whatever that means.

This one Panel/Surface Mount LED Voltmeter and Ammeter | Jaycar Electronics (https://www.jaycar.com.au/panel-surface-mount-led-voltmeter-and-ammeter/p/QP5584)

I don't have the wiring diagram.

[Blknight.aus]

you have 2 negatives on the meter,

connect all of the negatives of the cig sockets and usb to one of them the other to the battery negative.

if it reads a +ve reading (current going into the battery) switch over the 2 negatives

[Busted Syncro]

G'day All,

This problem is complex with LED digital volt and current meters from China. It's the way the meter uses the same +/- connections to measure the current from the battery and the voltage that run the actual digital meter.
What is needed is a meter that runs off the battery for the meter power supply and the load from the same battery that measures the current in the negative lead This will measure all the current from each device in the + circuit.
I said it's complicated. However, there is a simple solution.
EBAY has a 4 digit led amp meter that can measure 10A, 50 or 100amps that uses the negative load lead to sense current using the same supply for all + load devices. They are $7.00 each!
This is the link: Mini Digital 0.56inch LED Display Ammeter Panel Amp Current Meter Tester | eBay
(https://www.ebay.com.au/itm/Mini-Digital-0-56inch-LED-Display-Ammeter-Panel-Amp-Current-Meter-Tester/401704144927'ssPageName=STRK%3AMEBIDX%3AIT&var=671444252207&_trksid=p2060353.m1438.l2649)(Note: Caution. THIS Chinese meter uses red and black wires to sense the current and confusing so follow the wiring diagram exactly. Should be any other colours. It's a technical thing!)
There are other digital meters that have combined volt and amp displays as well. However, you will have to do your own research to check how they sense current and whether the amp meter can use the same voltage supply for load and amp meter voltage.

Another alternative is to use an independent digital amp meter and a shunt however, the same problem can occur with China type meters. You may not be able to use the same battery to power the meter and the loads.

I know a bit heavy for Sunday morning, let me think about the problem further after a cup of tea!!

Chris

[theelms66]

Picture number 11 of the Ebay link shows share power supply. https://uploads.tapatalk-cdn.com/20191123/336623256cc53e4c8dcf0813c221a814.jpg

[ChookD2]

Thanks all. I think I have it sorted now. Dave's explanation worked, i.e. all negs through amp meter and meter neg to batt.

Connected LED strip light and phone gave me just under 1A showed 0.98.

I'll get something else later that pulls a bit more current and see how that goes.

Cheers.