I've just ordered one of these - sound good and I can use it on my solar as well as other uses. Says it's made in the USA (maybe there is a USA in China?)

http://www.ebay.com.au/itm/Digital-LCD-Watt-Meter-Battery-Balance-60V100A-DC-RC-Volt-Ammeter-Amp-Analyzer-/321507941717?

D and D wrote:

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Which one?

Dave

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 The one at the top:

Digital LCD Watt Meter Battery Balance 60V100A DC RC Volt Ammeter Amp Analyzer

This device appears to be similar, only in a different package:

http://www.rc-cars-planes.com/docs/wu100v2_user_manual.pdf

My first impression was that the wires looked a bit light. At 10A, the dissipation in the wires and shunt would be 0.5W, but at 50A it would be 12.5W. The voltage drop at 50A would be 0.25V.

7.2 Maximum Current Capabilities 

Current flowing through Watt's Up and its supplied wires generates heat due to the resistances of the wires and of the precision internal current shunt used for current measurements. Though very low (~ 0.004 Ohms in 14 gage wires and 0.001 Ohms in shunt), these resistances are finite and at high currents the heat generated becomes noticeable.

At 75 Amps, approximately 28 Watts of heat is produced -- mostly in the Watt's Up's wires. ... The high current handing capabilities of Watt's Up will be maximized when the Watt's Up's SOURCE and LOAD wires are kept short and cool. Cut the wires as short as is convenient for high current operation. A fan blowing over the wires will help their cooling. At moderate currents there is little heating. Using a "three-wire" connection will also lower heat generation.

The idea that wires need to be cooled is scary.

We have one of these in the new electrical dist box I put in.

http://www.ebay.com.au/itm/Digital-LED-AC-Volt-Amp-2-in-1-Combo-Meter-Voltmeter-Ammeter-0-2-99-9A-/161361280122?pt=AU_B_I_Electrical_Test_Equipment&hash=item2591e1bc7a

I dont expect great accuracy, but it does give me some idea as to the state of our current draw and volt drop.

Very neat current transformer inside the box, just had to pass an active through the device and an active neutral for the volts.. sweet but probably not approved, so far no dramas.

Phil I was about to jump on you and say WTF have you done..

Then I noticed that it was in 237v NOT 23.7v
If it had of been a Low Voltage range I would of Said...
" Phil that is not a Thing that you should be showing People.. "

As you will know.... Never EVER MIX low voltage with high voltage..

12v-48v should never be Mixed with 240v..



so Phil I'm not gonna jump on you and just say Well Done.... [ Please Note this partial Fix has been done By an electrician - Do not do this unless you are an Electrician ]

So a Good little fix...

Juergen..

Psst -- Phil I don't need that.. I have a Victron BMS 600 which tell me My DC loads and with My style of system I don't need to really need to worry about the high voltage stuff I'm after the Battery stuff..

Plus My inverter has all that information on it at a glance..

dorian wrote:

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The idea that wires need to be cooled is scary.

-- Edited by dorian on Tuesday 11th of November 2014 06:27:46 AM

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 I agree that implies an overload and fire risk.

As with all these power / current detectors they all seem to be stuck on Ohms law.  Are there any using a hall effect device?  I couldn't find any affordable ones.

Thanks guys, I needed to isolate the aircon, so a full replacement of the very weak Jayco system was in order. So I thought why not a volt/amp meter as well? Ebay came to the rescue.

BTW This job has been designed and completed by a licenced electrician and has a full certificate of compliance with it. Dont even think about doing something like this, yourself if you are NOT an electrician!

Cheers

Cloak wrote:

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dorian wrote:

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The idea that wires need to be cooled is scary.

-- Edited by dorian on Tuesday 11th of November 2014 06:27:46 AM

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 I agree that implies an overload and fire risk.

 

As with all these power / current detectors they all seem to be stuck on Ohms law.  Are there any using a hall effect device?  I couldn't find any affordable ones.

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 Im pretty sure that this has a current transformer in the guts someplace, a hall effect would be a lot more expensive. Also it is not that accurate, specs say 1%, I doubt it..

I agree about Ohm's Law.. hasnt been repealed as yet.. Find a new one and make a fortune.. 

Phil C wrote:

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Cloak wrote:

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dorian wrote:

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The idea that wires need to be cooled is scary.

-- Edited by dorian on Tuesday 11th of November 2014 06:27:46 AM

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 I agree that implies an overload and fire risk.

 

As with all these power / current detectors they all seem to be stuck on Ohms law.  Are there any using a hall effect device?  I couldn't find any affordable ones.

---

 Im pretty sure that this has a current transformer in the guts someplace, a hall effect would be a lot more expensive. Also it is not that accurate, specs say 1%, I doubt it..

I agree about Ohm's Law.. hasnt been repealed as yet.. Find a new one and make a fortune.. 

-- Edited by Phil C on Friday 14th of November 2014 08:42:16 AM

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 HI Phil

Current transformer, DC ????

PeterQ

No its AC Peter, thats if you are talking about my modification. All AC mains.

Sorry guys I didnt read the posts correctly, the DC stuff will either need a hard wired ammeter or a hall effect, I have not seen one out there, all hard wired as far as I can see (for DC)

Now im confusing myself...

-- Edited by Phil C on Saturday 15th of November 2014 07:35:01 PM

I was thinking that some enterprising tech might be able to modify the cheap wattmeter by replacing the Ohmic shunt with the signal output from Silicon Chip's Hall effect based DC current clamp meter.

archive.siliconchip.com.au/cms/A_30669/article.html

The spec for the clamp meter is "Output: 1A = 1mV for AC and DC ranges". That is, for a current of 1A flowing in the cable, the meter generates an output of 1mV.

A current of 1A flowing through the 0.001 ohm shunt in the wattmeter would also produce a voltage drop of 1mV. Therefore, ISTM that all one would need to do would be to remove the shunt and wire the SC clamp meter's output and ground pins into the same location (assuming that the clamp meter's output is reference to the same ground).

Output: 1A = 1mV for AC and DC ranges
Resolution: multimeter dependent (100mA with 0.1mV resolution on multimeter)
Maximum DC current: 150A recommended (up to 900A if core is demagnetised afterwards)
Maximum AC current: 630A recommended 
Linearity: typically better than 4% over range at 25°C
AC frequency response: -3dB at 20kHz (meter reading depends on multimeter AC response)
Current consumption: 15mA

Ive built one of those Silicon Chip clamp meters. They do work ok but they need to be zeroed each time you use it. They do use a Hall device to measure the current.

Here is an update - I've tested the device against a digital VOM (the AVO batteries were gone) and I reckon the readings are virtually spot on. For a cheap 'toy' the innards seem good quality and as good as you get - definately not cheap junk IMHO. Anyway, I've attached some pics of the results using a headlight bulb and a small 12V battery that shows a dramatic drop in voltage and yes, the jumper cable I used did melt!
Good Luck.