I want to monitor my DC load not my battery discharge

harley

New Member
I've got a battery monitor up and running no problem, but I want to now install a second shunt and digital ammeter to monitor my DC load - hoping for some help on how to wire up the shunt as I cannot get anything to work
 

Brewman

Solar Addict
Placement is everything when using shunts. As you can see in my design I have the two shunts directly off the neg side of the battery. What makes them read differently is where the SCC Battery outputs are connected into the system.

The capacity monitor shunt is right off the battery and will only show what's going in and out of the battery. This will not show any PV amp draw due to its placement.

The second shunt has the SCC battery neg connected to it. Now it will see draw from both the battery and the SCC. This monitor can not tell the capacity of the battery.
 

harley

New Member
Do you mean a load that is not on the inverter, but connected directly to the battery?
correct, load is not on the inverter, load is on the battery and the battery monitor is showing correct current.

My test circuit has been simple: battery to a control/ switch box with negative bus bar and fuse box with fridge connected (thought a simple testing circuit like this would be best, but maybe not including my Renogy DC-DC into the circuit is part of what is creating an inability to get this setup working correctly???)

I'm using this Renogy for the 'summary' battery monitor and the Bayite monitor as you are for my 'total load' monitor. The problem I'm having is when I have tried integrating the 'total load' monitor into my test circuit, the 'total load' monitor only every reads a tiny fraction of the actual load amps - in fact it seems to just be "stealing" from the summary monitor e.g if the battery summary monitor was showing 5A prior to connecting in the 'total load' monitor, once the 'total load' monitor is connected it might show 0.2A, but the battery 'summary' monitor now shows 4.8A.
 

Fred S

Solar Addict
Ok, so your fridge is the load you're checking, and it's 12v and connected via a DC-DC converter to step down from a 24v battery?

I don't quite have straight in my mind (w/o a diagram) your component placement, but a couple of comments:
1) perhaps the shunt and meter are mismatched (some meters can be adjusted in the settings, e.g. for 100, 200, or 300 amp shunts). The shunt probably has its specs stamped on it, and the meter has to be set to match it. A meter set for 100a, but using a 300a shunt, would give you low readings.
2) if you put the shunt between the battery and the DC-DC converter (not after it), the result will be slightly more accurate because it will include the converter's losses as well as the load's draw. If you want to compare the DC load amps to the total amps from the battery, that's the best place to put it. However, like Brewman said, it also matters where the SCC is connected to the circuit (at least in daylight).

Your last sentence is interesting - can you sketch the circuit you have (no masterpiece expected), and snap a picture?
 

Fred S

Solar Addict
Also make sure your shunt is not wired backwards.
Good point! Although I have two of those same meters, and they will just read zero if the shunt is wired backwards.
I was disappointed that they wouldn't display negative amps, so I ran two on a single shunt, wired opposite. That let me read amps leaving the battery on one and amps into the battery on the other.
 

harley

New Member
@Fred S and @Brewman thanks for your help so far - I think I'm heading in the right direction, but still a few questions and testing required, but have made a bit of progress. I've got both meters now showing correct Amps. But, I think they could both just be showing the draw on the battery. I'll try and getting a diagram of wiring going now.
 

harley

New Member
@Fred S and @Brewman here is what I have as a wiring diagram so far
12V_wiring diagram_WIP.jpg

My test circuit is currently all of what is shown this diagram, with the exclusion of the car/starter battery and associated switch. With this setup I've now got the correct amps showing on both the battery monitor (Renogy monitor, not shown in diagram) and the total DC load monitor (bayite, not shown in diagram). So at this stage still a few questions:

How does that look to you? Does it look like the DC load monitor would be showing the total DC load? or is it actually just wired up as a second battery monitor (which I don't need ;))

As I don't have my solar panels yet I couldn't work out how to add more DC load (powered by a separate battery) to test if the two monitors are actually going to report different Amps. I've got a couple of small 6V lead acid batteries (from my kids little electric cars) to play with, but I was shorting the circuit out with what I tried - any idea how I could test?

After I get these two monitor running they way I want them and my solar panel arrives, I'll need to work out how to wire in the solar shunt/monitor (a 2nd Bayite - shown in the current wiring diagram, but not wired in).
 

Brewman

Solar Addict
Taking a quick look, it seems both meters will show total output but your battery monitor will never show any input. I'll post more later.
 

Brewman

Solar Addict
Ok, look at the pic of yours I edited. I added the sun input (lol) and showed battery draw from the PV on the negative side. If you follow the yellow directions It shows how it will bypass your battery capacity monitor shunt.

In the second pic I added the shunt where it needs to go for the capacity monitor. I didn't add in its power wire.
 

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harley

New Member
Ok, look at the pic of yours I edited. I added the sun input (lol) and showed battery draw from the PV on the negative side. If you follow the yellow directions It shows how it will bypass your battery capacity monitor shunt.

In the second pic I added the shunt where it needs to go for the capacity monitor. I didn't add in its power wire.
rockin' roll! let me take a look over now :))
 

harley

New Member
Ok, look at the pic of yours I edited. I added the sun input (lol) and showed battery draw from the PV on the negative side. If you follow the yellow directions It shows how it will bypass your battery capacity monitor shunt.

In the second pic I added the shunt where it needs to go for the capacity monitor. I didn't add in its power wire.
ok so, is the following true. Your edit represents three monitors/shunts that work as follows:
1). a battery 'summary' monitor - this will show (in simple terms) both of either power being taken from battery or power/ charge going to battery from Solar and car Alternator?
2). a total DC load monitor - this will show the total of all power being consumed by 'things' connected to the circuit through the fuse box?
3). a solar monitor - this will show the amount of power the solar panel if providing the circuit via the CC?

If the above is true, fantastic, that is what I'm after. The only other tweak I plan on is wiring up a switch on the solar monitor shunt so that I can flick between:
(a) showing the amount of power the solar panel is generating and
(b) showing the amount of solar power is going to the battery as charge (i.e any solar power being generated beyond the total load power requirements)
 
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