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Forum Index : Microcontroller and PC projects : Yet another USB power monitor

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TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6269

Posted: 06:47pm 10 Nov 2016

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I don't think this one has been discussed here before.
Model KCX-017

I like the 0.5 second updates and the simultaneous display of voltage and current.
It also has an accumulated power consumed in mAh - not something that interests me but it might come in handy.
The display is nice and clear.

Internally, it uses a 358IC and 0.025 ohm shunt for current measurement.

A review:
http://lygte-info.dk/review/USBmeter%20KCX-017%20UK.html

Jim

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Cremo
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Joined: 21/07/2015
Location: Italy
Posts: 36

Posted: 08:43pm 10 Nov 2016

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Very interesting.
Thank you.
Pietro

paceman
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Joined: 07/10/2011
Location: Australia
Posts: 1329

Posted: 02:00am 11 Nov 2016

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Yes I've had one of these plugged in ahead of my USB-Serial converter for about six months now Jim - thanks for the review link. They market it as a charging (cumulative mAh) meter but I'm not quite sure of the point of that; I just find it useful to monitor the USB port voltage and current flowing out, and for the price it does a pretty good job.

The only minor gripe I'd have is that it 'only' displays current to 2 dec. places i.e. X.XX amps so the lowest draw you can see is 10mA. It'd be nice to be able to switch the range to see another dec. pt. but still, not bad for the price. Voltage displays to X.XX too and that's quite adequate.

Greg

WhiteWizzard
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Joined: 05/04/2013
Location: United Kingdom
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Posted: 02:44am 11 Nov 2016

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Has anyone thought of making one of these with a MicroMite? I know they are cheap to buy, but they all seem to have a trivial issue (just read the last post here!).

Something like BigMik's excellent Serial BackPack, along with a 0.96" OLED, a shunt, and a minimal program, and you have a cheap a customisable Power Monitor.

Grogs; another PCB on the way from your 'factory' perhaps?

bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2949

Posted: 04:45pm 11 Nov 2016

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WhiteWizzard said Has anyone thought of making one of these with a MicroMite? I know they are cheap to buy, but they all seem to have a trivial issue (just read the last post here!).

Something like BigMik's excellent Serial BackPack, along with a 0.96" OLED, a shunt, and a minimal program, and you have a cheap a customisable Power Monitor.

Hi Phil,

thanks for the Plug, I think the Nanomite or my soon to be formally released PicoMite might be a better option if you wish to keep things really small..

The NanoMite is 15mm x 15mm (0.59") the PicoMite (a 14pin version of the Nanomite) is a 15mm x 19mm board.

Couple it with the long, thin Oled display I posted a while ago and you have a USB stick sized board..

I am happy to offer bare NanoMite or PicoMite PCBs to anyone who wants to play around with designing one.

Kind Regards,

MickEdited by bigmik 2016-11-13

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6269

Posted: 08:07pm 11 Nov 2016

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If I was rolling my own, I would look closely at the INA219 instead of a 358 for the current sensing.
The INA219 is I2C and a 12 bit A/D.

It is still not isolated but can handle 26V on the sense inputs so not too bad.

Jim

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greybeard
Senior Member

Joined: 04/01/2010
Location: Australia
Posts: 172

Posted: 03:49am 12 Nov 2016

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I've used the accumulated power measurement to monitor both power used from a battery and output from a solar panel to see if I have a reasonable match between consumption and charge. It's been very handy and an easy way to check quickly what is going on.
I have a 'plug together' wifi monitoring package with an modemcu eps8266 board, 6V 1W solar panel and a 2000mAh USB battery pack. (~ $10 all up) and all off the shelf (well eBay and Kmart) Once I get a few more numbers I'll write it up in another thread.

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