Battery Voltage Monitoring

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Paul
Paul's picture
Battery Voltage Monitoring

Ned asked about monitoring battery voltage:

" I have a Hivetool setup that I've just put off-grid utilizing solar and
a 12v battery. Is there a way to connect and monitor the battery voltage
through the Hivetool graph or does it only monitor the battery voltage
if it's being powered by that battery? Currently the system is using a
micro-USB connection tapped off the solar charger. Thanks for making
this system, it's been really great to monitor flow/growth and any
assistance you can give would be appreciated."

Others might benefit from this, so I've posted it on the forum,

1. You can hook the positive of the battery to the +12 pin of the blue connector (the side closest to the LED).
2. You should not need a ground as all the DC system shares a common ground.
3. It will have to be calibrated. You can short the two blue pins (with nothing connected) to get a zero reading.
4.It is not graphed yet but is recorded in the database and displayed in the table.

Ned again:

Will I be able to track true voltage or do I need to calibrate it to
register 5vdc? I was hoping to monitor battery voltage to ensure the
solar panel is charging correctly and the system will continue to
function. Thank you again for any assistance.


Here is a screen shot of what I think you want to do. We are monitoring the 12 volt battery connection. The voltage is in the right column (gray background).

Image: 
MarkG
Battery Voltage Monitoring

Hi Paul

I too want to monitor 12v battery voltage.

I'll be using a 12v > 5v buck/boost device, powering the micro USB port of the RPi as recommended.

To confirm and so I don't fry anything, I simply need to add the 12+ line taken from before the buck/boost and connect it to the 12+ to the Hivetool Hat - as circled on the pic attached?

Thanks

Image: 
Paul
Paul's picture
Battery Voltage Monitoring

Yes. That is correct. No ground is needed as the 12v > 5v buck/boost device is not isolated (shares a common ground). I have not tested the maximum voltage but it uses a 200:1 voltage divider to reduce the 12 volts to 60 millivolts that is within the range of the HX711.

MarkG
Battery Voltage Monitoring

That works a treat!

I have 95Ah 12 battery > 12/24v 5A buck to 5v device > RPi

The buck device has 4 x USB sockets so I think I'll be good to drive 4 x Hivetools as using a little USB dongle the 5V is spot on and consuming around 320mA in what is I assume an idle state.

I've the 12+ wired into 12v side of the buck device and changed the Intercept value so that the voltage detected by Hivetool is pretty close to what my multimeter says....13.87.

I forgot to check voltage was zero when shorting out the 2 x blue pins - is there anything else I should do? I'm really only looking for trends downward to alert on battery charge state.

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