OldPeculier Posted April 25, 2017 Report Share Posted April 25, 2017 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; Link to comment Share on other sites More sharing options...
rusty69 Posted April 25, 2017 Report Share Posted April 25, 2017 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/ Link to comment Share on other sites More sharing options...
GUMPY Posted April 25, 2017 Report Share Posted April 25, 2017 (edited) 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 Link to comment Share on other sites More sharing options...
WotEver Posted April 25, 2017 Report Share Posted April 25, 2017 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. Link to comment Share on other sites More sharing options...
GUMPY Posted April 25, 2017 Report Share Posted April 25, 2017 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 Link to comment Share on other sites More sharing options...
rusty69 Posted April 25, 2017 Report Share Posted April 25, 2017 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. Link to comment Share on other sites More sharing options...
WotEver Posted April 25, 2017 Report Share Posted April 25, 2017 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. Link to comment Share on other sites More sharing options...
rusty69 Posted April 25, 2017 Report Share Posted April 25, 2017 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 Link to comment Share on other sites More sharing options...
RD1 Posted April 26, 2017 Report Share Posted April 26, 2017 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. Link to comment Share on other sites More sharing options...
OldPeculier Posted April 26, 2017 Author Report Share Posted April 26, 2017 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. Link to comment Share on other sites More sharing options...
WotEver Posted April 26, 2017 Report Share Posted April 26, 2017 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. Link to comment Share on other sites More sharing options...
mark99 Posted April 26, 2017 Report Share Posted April 26, 2017 (edited) what a load of old shunts. Edited April 26, 2017 by mark99 Link to comment Share on other sites More sharing options...
David Mack Posted June 19, 2017 Report Share Posted June 19, 2017 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? Link to comment Share on other sites More sharing options...
Chewbacka Posted June 19, 2017 Report Share Posted June 19, 2017 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. Link to comment Share on other sites More sharing options...
WotEver Posted June 19, 2017 Report Share Posted June 19, 2017 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. Link to comment Share on other sites More sharing options...
cereal tiller Posted June 19, 2017 Report Share Posted June 19, 2017 (edited) 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 Link to comment Share on other sites More sharing options...
WotEver Posted June 19, 2017 Report Share Posted June 19, 2017 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. Link to comment Share on other sites More sharing options...
Onewheeler Posted June 20, 2017 Report Share Posted June 20, 2017 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. Link to comment Share on other sites More sharing options...
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