Micromanaging DC loads

[rmaddy]

For the last few hours my battery monitor was showing 16 extra watts being drawn from my battery than I normally see. I could not figure out where it was coming from. I finally found that a rarely used light switch for an external LED light was on. I must have bumped it unknowingly.

Anyway, this got me thinking about all of the loads I have on my system. The battery monitor can only tell me how many watts of DC loads I have. But what if I wanted a way to monitor each DC load and its current usage? I could see how many amps or watts are currently being used by my fridge, furnace, water pump, various lights, etc.

Just brainstorming some ideas. Is there something that can be wired into each connection of my DC fuse box, for example, and for each connection it could provide how many amps are being used? Then somehow all of those could be wired into a Raspberry Pi. Then I could access the readings and display the amps usage of each connection.

Has anyone done anything like this or have some ideas on how this could be done?

 

[HRTKD]

If I were doing this, I would want it done within the DC side of the main distribution panel. Where each fuse is installed, put in some sort of shunt. It wouldn't have the fine granularity of reporting that you would want however. My DC fuses often are fused for multiple devices.

 

[Bud Martin]

You will need multi channel DC power monitoring module of some sort, not sure if there is one off the shelf that you can buy.

 

[rmaddy]

My DC fuses often are fused for multiple devices.

I'm sure that's how most people do it. I had just enough spots on my 24V fuse box and my 12V fuse box to give each individual item its own fuse. 24 independent DC loads.

You will need multi channel DC power monitoring module of some sort, not sure if there is one off the shelf that you can buy.

So far I've looked into current transducers. Now I'm beginning to look into some sort of small ammeters.

 

[Symbioquine]

I would want it done within the DC side of the main distribution panel. Where each fuse is installed, put in some sort of shunt.

The Victron Lynx Distributor is so close to this concept, but sadly only allows for monitoring fuse status, not current/power throughput. (And is pretty expensive for what you get.)

 

[rmaddy]

The Victron Lynx Distributor is so close to this concept, but sadly only allows for monitoring fuse status, not current/power throughput.

Having an LED come on when a fuse blows is pretty simple. Many cheap fuse boxes have this. My 12V fuse box has the LEDs. You can find the circuits for these online. It's mostly an LED and a couple of diodes, maybe a transistor. Monitoring and reporting current/power requires a lot more parts and processing.

 

[efficientPV]

You could have each fuse acting as the shunt and monitor the voltage across it. Use a simple opamp section for each fuse and feed that into the micro.

 

[John Frum]

Option A:
Add one of these to each branch circuit dowstream of the fuse.

Option B:
Get a dc clamp meter like this.

AC/DC Digital Clamp Meter, Auto-Ranging 400 Amp - CL390 | Klein Tools

Klein Tools CL390 is an automatically ranging true root mean squared (TRMS) digital clamp meter. It measures AC/DC current and NCVT via the clamp, AC/DC voltage, DC microamps, resistance, continuity, frequency, capacitance, and diodes via test leads, and temperature via a thermocouple probe. It...

www.kleintools.com

 

[rmaddy]

Option A:
Add one of these to each branch circuit dowstream of the fuse.

What does "these" refer to in your statement?

Option B:
Get a dc clamp meter like this.

I have a good multimeter with clamp. But my original post is not about testing a circuit on occasion. It's about setting up a 24/7 monitoring system on all DC loads. Using the DC fuse boxes seems like a good place since that's a common path for all existing wires.

 

[John Frum]

What does "these" refer to in your statement?

My bad.

DROK® Digital Multimeter DC 6.5-100V 20A Voltage Amperage Power Energy Meter DC Volt Amp Tester Gauge Monitor LCD Digital Display with Blue Backlight Measuring Volts Current with Built-in Shunt : Amazon.ca: Tools & Home Improvement

DROK® Digital Multimeter DC 6.5-100V 20A Voltage Amperage Power Energy Meter DC Volt Amp Tester Gauge Monitor LCD Digital Display with Blue Backlight Measuring Volts Current with Built-in Shunt : Amazon.ca: Tools & Home Improvement

www.amazon.ca

 

[BrickedKeyboard]

Even really simple products can be expensive when made in small volumes. Why not just measure at the AC side? There are numerous all in one AC monitoring devices that report via wifi on Amazon for about $100-$300.

For example : the emporia one is only $109 at the moment with 8 sensors. With a solar driven subpanel you can install one perfectly safely because you can just turn off your inverter and work on it cold.

 

[rmaddy]

Why not just measure at the AC side?

Thanks but I rarely ever have any AC loads. I have lots of DC loads. As stated in the OP, my goal is to measure the DC loads.

 

[12VoltInstalls]

The drok meter suggested sums KWh. US$13. I have one in a box somewhere

It summaries KWh too.

I have the 120VAC model, too, to track my grid usage and input

 

[Alloy]

Try a search for "multi channel dc current monitoring"

 

[Rogerb]

This might help with what you're looking for.

Quadro shunt modules SCQ25, SCQ50 and SCQ25T - Simarine

With quadro low-amp shunt modules you can monitor the current flow of the 4 individual devices. Each module has a built-in, programmable alarm signal relay.

simarine.net