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tcerit avatar image
tcerit asked

victron smart shunt can not identify second mppt

hello. this will be my first question here so I apologize in advance if I am wrong.


The system is as follows: in my system: I have 1 victron smart shunt 1000a, 1 victron 100/30 dc to dc, 2 victron mppt 100/50, 4 megacell 200ah lifepo4 (total 800ah) batteries, 4 apex 205w solar panels (total 820w). 2 of them (410w) are connected to one mppt and the other 2 (410w) are connected to the other mppt. so I have ensured that it produces a maximum value of 68.3 amps in total.


my question is as follows: when I had 1 mppt (100/50) (when the entire 820w solar panel was connected to this mppt), the smart shunt was showing me the total current value from the solar panel exactly the same as the mppt. for example, if I read a value of 25a on the mppt from the solar panel, I could see the same value on the smart shunt (for example, when there was no use). After adding 1 more mppt and providing the connection, for example, when I read 20a from one mppt and 20a from the other mppt, the amperage value I expect to see on the smart shunt should be approximately 20a + 20a = 40a, while I can only see 20a. when I start the vehicle, for example, if the vehicle is getting 30a from dc to dc and 20a from mppt, I can see 50a. but the other mppt produces 20a in the meantime, so I can see 50a on the smart shunt when I should be able to see 70a in total. this situation is quite annoying.


The smart shunt does not recognize the second mppt I just installed, i guess.


note: all updates are done and all devices are up to date.

MPPT ControllersSmartShunt
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Alexandra avatar image
Alexandra answered ·

@tcerit

And you are sure you have connected the new mppt before the shunt (not onto the battery) ? Like on the load/charger side?

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tcerit avatar image tcerit commented ·

I connected the new mmpt as follows: I connected the one coming from the solar panel to the pv input, and the cables coming out of the part that says battery to one of the batteries I connected in parallel.

I did all this with the old mppt, shunt and battery connections.

Is this what you want me to do? Disconnect the shunt from the circuit. Complete the 2 mppt connections. see that the system is working, the current is coming and then connect the shunt as if it were a new device. so you want me to leave the connection of the shunt to the last?

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Alexandra avatar image Alexandra ♦ tcerit commented ·

I wanted to confirm you have connected it like it is in the install manual. Is your system 12v or 24v?

Might be easier for us to understand if you drew a picture. Doesn't have to be a fancy one hand drawn will suffice.

1000045856.jpg

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tcerit avatar image tcerit Alexandra ♦ commented ·

there is a situation that I realized: I connected the previous mppt device directly to the mains, not to the battery. i connected the new device directly to the battery. could this be the reason ? if yes, I will connect the new mppt device directly to the mains as in the old mppt device. thank you in advance for your response.

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pwfarnell avatar image pwfarnell tcerit commented ·
Yes, this is your problem. If you connect the MPPT negative direct to the battery the MPPT power does not flow through the shunt so it can not be measured. Move the connection to the same location as the old MPPT.
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