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nimaz avatar image
nimaz asked

MPPT 150/70 only charges at max 15w - while old MPPT pulled 300w+

Hi,

So I just changed out a 10 year old Morningstar 45 MPPT to Victron 150/70 VeCan.
Problem is that even if I get 35v on the PV side the controller charges at max 15w normally more like 6w.

It's the same connections I had on the Morningstar and it had no issues pulling in 300w in the same conditions. (Connected are 8x250-270w 24v panels in parallel). Battery is a 1000A 12v consisting of 6x2V flooded cells.


Any suggestions what to do to get the Victron to work as expected?

I have a 100/50 Victron also and that is working fine but with that one I have 4x410w panels in two pairs so the voltage is 65-70v.


I can try swapping the 8 connected solar panels to 4 pairs of 2 to push the voltage up to 65-70v also, but it will require quite some work to do, so I'd first like to hear any suggestions on what might be wrong first...

Can't upload pictures to this post for some reason, will try to add in first comment.

MPPT SmartSolar
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nimaz avatar image nimaz commented ·

As apparently uploading pictures inline or as attachment do not work uploaded to Google Drive then:
Here is how the 150/70 looks like
https://drive.google.com/file/d/13pmHOB39VcO9DAH2ZgMeOh6idkEHDkE3/view?usp=drive_link

And the 100/50 taken less than a minute later
https://drive.google.com/file/d/1QAW1j1d_eu0lVvHPD9vr54mBxHJ1F0YW/view?usp=drive_link

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Alexandra avatar image
Alexandra answered ·
@Nimaz

Confirm you have the same settings on both?

It will work better with higher PV voltage. But i do hear where you are coming from in rewiring. So do make it a near future project.

The thing to check would be rebulk offset maybe?

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nimaz avatar image nimaz commented ·

Thank you @Alexandra,

I found the fault - as you pointed out wiring could be improved and that was what I did, but I forgot to attach the negativ battery terminal in my battery box.

Still wondering how the controller even started with no negativ connected to the battery, as I have a fuse on the positive side and moving that in the "on" position started the controller even if the battery was not connected...

Was really helpful not to look at the stuff for about 1h, then read the rewiring part and go back with a multimeter to see that battery terminals on the controller (negativ was not connected) show almost 16v. Open the battery box and look "what is this extra cable not connected..." and feel like a idiot :)

Again thank you and have a nice weekend.

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Alexandra avatar image Alexandra ♦ nimaz commented ·
@Nimaz

Lol. Was my first thought. The two screenshots showed slightly different battery voltages.

Awesome that it is sorted.

Mppts can power up from the PV side. Awesome feature to use to black start lithium's and offgrid unmanaged sites.

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