wiring an ammeter

[OldPeculier]

I bought one of these to put in between my solar controller and batteries but somehow I managed to get confused and wired it up wrong so it went bang.  I've now got another one and don't want to repeat my mistake.  Could any kind soul sketch me a diagram I could follow?  

The wiring instructions are;

 

[rusty69]

28 minutes ago, OldPeculier said:

I bought one of these to put in between my solar controller and batteries but somehow I managed to get confused and wired it up wrong so it went bang.  I've now got another one and don't want to repeat my mistake.  Could any kind soul sketch me a diagram I could follow?  

The wiring instructions are;

 

I bought some from China for about 2 quid each. Haven't connected them yet, but was going to use this info as no instructions came with it

 

http://diyprojects.eu/how-to-wire-digital-dual-display-volt-and-ammeter/

[GUMPY]

Power supply needs to be from an independent source not your batteries.

ETA it will go bang if you supply it from the same source as you are monitoring.

I used to power mine from a pp3 with a push button to switch it on when I needed to read it. Battery lasted about a year

Edited April 25, 2017 by Loddon

[WotEver]

2 hours ago, rusty69 said:

I bought some from China for about 2 quid each. Haven't connected them yet, but was going to use this info as no instructions came with it

 

http://diyprojects.eu/how-to-wire-digital-dual-display-volt-and-ammeter/

That looks about right. OP should substitute  the yellow wire where the above link shows a blue one. 

1 hour ago, Loddon said:

Power supply needs to be from an independent source not your batteries.

ETA it will go bang if you supply it from the same source as you are monitoring.

If wired as per the above link I see no reason why that should be the case. 

[GUMPY]

49 minutes ago, WotEver said:

That looks about right. OP should substitute  the yellow wire where the above link shows a blue one. 

If wired as per the above link I see no reason why that should be the case. 

Mine came with big warning not to use the measured supply for the psu.........

They cold have saved the cost of a connector if it does take its power from the measured supply

[rusty69]

7 minutes ago, Loddon said:

Mine came with big warning not to use the measured supply for the psu.........

They cold have saved the cost of a connector if it does take its power from the measured supply

It's a shame they don't all come with wiring instructions, but I guess you can't  expect too much for £1.86 Inc p&p. 

[WotEver]

7 minutes ago, Loddon said:

They cold have saved the cost of a connector if it does take its power from the measured supply

I didn't say that it does take the supply from the measured voltage. It can take the power from the measured supply as long as the measured supply is within range. If the supply being measured is higher than 30V then the unit must be supplied with a separate supply of suitable voltage. 

[rusty69]

7 minutes ago, WotEver said:

I didn't say that it does take the supply from the measured voltage. It can take the power from the measured supply as long as the measured supply is within range. If the supply being measured is higher than 30V then the unit must be supplied with a separate supply of suitable voltage. 

That's how I understand it. 

Will let you know when I get round to wiring mine up

 

[RD1]

15 hours ago, WotEver said:

I didn't say that it does take the supply from the measured voltage. It can take the power from the measured supply as long as the measured supply is within range. If the supply being measured is higher than 30V then the unit must be supplied with a separate supply of suitable voltage. 

I totally agree too, but to help clarify, the current load in amps, is actually measured from the return, ie 0 volt line.

(It's the same current flowing in the circuit where ever you measure it).

Some people might think that the current should be measured from the positive supply going to the load, and I think this is where a few people are getting lost. Hope it helps. 

 

[OldPeculier]

20 hours ago, Loddon said:

Power supply needs to be from an independent source not your batteries.

ETA it will go bang if you supply it from the same source as you are monitoring.

I used to power mine from a pp3 with a push button to switch it on when I needed to read it. Battery lasted about a year

Well there seems to be some debate.  Perhaps the above might be the best option.

[WotEver]

3 hours ago, RD1 said:

I totally agree too, but to help clarify, the current load in amps, is actually measured from the return, ie 0 volt line.

(It's the same current flowing in the circuit where ever you measure it).

Some people might think that the current should be measured from the positive supply going to the load, and I think this is where a few people are getting lost. Hope it helps. 

Yes. Basically if you don't understand the circuit as shown in the link below then you shouldn't wire it in yourself. If you don't wire it in the -ve line as shown then you'll probably blow it up however you power it. 

http://diyprojects.eu/how-to-wire-digital-dual-display-volt-and-ammeter/

44 minutes ago, OldPeculier said:

Well there seems to be some debate.  Perhaps the above might be the best option.

No debate, simply wire it as above. 

[mark99]

what a load of old shunts.

 

 

Edited April 26, 2017 by mark99

[David Mack]

Do these LED dual voltmeter/ammeters measure current in both directions? i.e. can I wire one to show the net current into/out of the battery when charging and when using power?

[Chewbacka]

59 minutes ago, David Mack said:

Do these LED dual voltmeter/ammeters measure current in both directions? i.e. can I wire one to show the net current into/out of the battery when charging and when using power?

Some need an ISOLATED supply if it is to read in both directions.  

[WotEver]

Most (all?) of the cheap Chinese ones I've seen on eBay only read in one direction. I do actually have a couple that I bought a while back to see how effective it will be to have one shunt with two displays, each wired the opposite way. 

[cereal tiller]

1 hour ago, Chewbacka said:

Some need an ISOLATED supply if it is to read in both directions.  

 

13 minutes ago, WotEver said:

Most (all?) of the cheap Chinese ones I've seen on eBay only read in one direction. I do actually have a couple that I bought a while back to see how effective it will be to have one shunt with two displays, each wired the opposite way. 

The one I have requires an Isolated Power Supply,I power it with a 1.2 AMP/HR 12Volt Battery Via a Double Pole Double Throw Toggle Switch  ,when the Switch in is Meter on position the battery is isolated from the main 12 Volt System,when Meter Switched off it;s supply battery is  charged by the main Battery Bank Via a Diode

Edited June 19, 2017 by cereal tiller

[WotEver]

Yeah, I bought two of the "£5 complete with 100A shunt" ones to play with. I figured at that price what's to lose?  I just haven't had time to check them out. 

These definitely only display in one direction. 

So two displays wired from the same shunt should show +ve and -ve flow. 

[Onewheeler]

I have similar, it works fine. Mine has an external shunt. Only minor grumble is that with low loads which should be within the resolution of the current metering it doesn't register. Planning to investigate further this week. It's fascinating to watch the Webasto consumption changing through its cycle.