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Interest: Remotely accessible 30A current meter / data logger.

Discussion in 'The Development Lab' started by Barnabybear, Sep 19, 2016.

  1. Barnabybear

    Barnabybear New Elf

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    Hi, a quick post to see if a 30A remotely accessible current meter / data logger would be of use to people. From the links below the parts can be purchased for under $7.00US (all from same site for ease).
    The unit can report via locally accessible web page, or with the data logger option, save the values to an SD card as a comma separated .csv file.
    So basicaly a current meter with it's own web page. You can sit in your workshop set all your lights to full and see what the current draw on your power supply is without leaving the house. If its a bit high you can adjust your golbal settings to suit, or if a bit low get streight on the net and order some more lights.
    A full set of the items can be fitted to each power supply for anytime measurements, or just fit the sensor. The processor and SD card (if needed) can be attached via a 3 pin plug when needed to keep the cost down.

    EDIT: found this video (not me) but you will get the idea - they use mostly the same components; ESP8266 ADC with ACS712(5A) - YouTube

    I’m not intending to do a group buy or supply any parts. The links to the main parts needed are below, and the reason for asking for interest will dictate how well I document this. The first unit for myself will be finished later this week and I will confirm that it is safe to order parts if you want to assemble one yourself. This is not a complicated build, it should take less than an hour.

    The 3 main parts.

    Current sensor.
    30A any voltage AC or DC. Built into your enclosure, one is required for each power supply. Can be picked up for $1.80US.
    http://www.ebay.co.uk/itm/1PCS-30A-r...-/191736650984
    Data sheet https://www.sparkfun.com/datasheets/...oards/0712.pdf

    Processor.
    A wemos D1 mini. Basically an ESP8266 development board which reads the sensor and the gets the data to you. It has built in regulator and CH340 usb to serial converter. $3.30US.
    http://www.ebay.co.uk/itm/D1-Mini-No...-/191813500136
    Site http://www.wemos.cc/Products/d1_mini.html
    Schematic http://www.wemos.cc/Products/images/d1_mini.pdf

    SD card holder (optional).
    A micro SD card holder if you want this option. $1.80US.
    http://www.ebay.co.uk/itm/1PCS-Micro...-/191943530836

    The other bits needed.
    5V power supply (batteries are fine).
    SD card if used.
    Some light 3 core cable (doesn't carry any load).
    Possably some ring terminals and heatshrink dependant on your setup.
     
  2. David_AVD

    David_AVD Bite my shiny metal ass!

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    Is the idea to measure the current on the mains or low voltage side of the power supply?
     
  3. OP
    OP
    Barnabybear

    Barnabybear New Elf

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    Hi, I'm going to measure the low voltage side of my supplies. With the given components, if connected the correct way round the current sensor module will return 2.5V to 0V to reflect a current of 0A to -30A. Applied to the wemos ADC with its on board voltage divider (220K:100K) it should still return 800 values for the range, giving a a senceitivity of about 40mA.
     

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