That would be correct.

View attachment 277341

Part of the problem is Power Supply BLK - and BLK Common are common to each other. Even wired as above I am not sure it will work. There are plenty of ways to do what you want to do but they are a bit more complicated and require Isolation. As crutschow pointed out separate power for each module.

Ron

I need my project something like what I planned. It has to correspond to 3 main objectives. 1. Use the solar power as much as possible 2, automatically use the PSU if needed. 3. be a UPS as well.
That's why I planned it the way I just shared it a couple of minutes ago.
Any better idea is welcomed
But please also consider that the fact, I am poor LOL

 

The measured current must only be connected to the negative pole of the power supply and the negative pole of the load.

This indicates to me that the power supply ground Is connected to shunt negative. You can check this with an ohmmeter. If the is the case, when you connect the power supply to both ammeters, you are also connecting together the grounds of your you two 24V supplies, which explains why your readings are incorrect.

Try using two separate power supplies for the meters and see if things look any better.

 

This indicates to me that the power supply ground Is connected to shunt negative. You can check this with an ohmmeter. If the is the case, when you connect the power supply to both ammeters, you are also connecting together the grounds of your you two 24V supplies, which explains why your readings are incorrect.

Try using two separate power supplies for the meters and see if things look any better.

In the last post, I shared my setup. I do it here again. I cannot ad the load to the shunt directly as I need DC-DC step-down converters to keep the voltage at a certain level. My most expensive 32bit control board just died because the last solar controller supplied too much voltage (it has broken) and the mainboard voltage controller IC has gone. (32V is the maximum it can handle) That's another reason I came up with the idea, to use DC-DC step-down converters, to be sure!

 

Now modify your circuit diagram to connect the thick black and thin black wires of your ammeters togther and you will see that the two shunts are connected in parallel such that the load current can flow through both of them.

 

They are operating from a totally separated PSU.

Each meter must be operated from a separate isolated power supply.

 

Each meter must be operated from a separate isolated power supply.

Thank you so much! This worked!!! Frankly, I would have never thought of this!
Bit disturbing though, as if no electricity the meter won't show anything. However, I don't care. Point is, the system is beautifully working and now the meters correctly show, where the most current is flowing.
Now, the next step... I need to find some logical circuit, "idea" to switch OFF the main power supply when NO printer is running. And of course, switch ON when even 1 printer goes online. (in standby it eats 10W! - so... yeh, you see my point)

Thank you everyone for all the help! I highly appreciate it!

 

Yay, we love happy endings.

Ron

 

I don’t get no respect. That is the second time in two days that someone else was credited with a solution I had already suggested and the TS ignored.

 

I don’t get no respect. That is the second time in two days that someone else was credited with a solution I had already suggested and the TS ignored.

I noticed that and you have my unconditional respect. Not that it helps.

Ron