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charlie996 avatar image
charlie996 asked

Victron 75/15 won’t work.

Fitted a new Victron smart solar controller today to replace the cheap junk in our caravan.

Connections dead easy and the same as the old unit IE +&- on the battery side and +&- on the PV side.

In short the new Victron simply doesn't charge the battery

I logged into the app which shows no power from the PV panel whatsoever despite it being sunny all day today.

Left it for 3 hours but it still hasn’t charged the battery and still showing 0 power from the PV.

So I took it out and put the old controller back in which immediately started charging the battery.

Am I missing something ? I understand this unit should be plug and play ? I did connect the battery up first as I was advised I should then hooked up the PV …..

Any advice appreciated before I send it back ?

Many thanks

MPPT Controllers
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6 Answers
anthony avatar image
anthony answered ·

It would be essential to see a screenshot or two from the app in order to help you with this.

Also battery brand and model would be good to know.

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charlie996 avatar image charlie996 commented ·


Sorry struggling with this site.

Below is the only screenshot I have. I have removed the unit and reinstalled the original which is working fine.

The app screenshot shows that the 75/15 was not reading any power from the 80W solar panel. The leisure battery is a two year old Yuassa 110 amp

d3c6d0d7-fdf6-4e7b-be26-7163fd4ea873.png

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klim8skeptic avatar image klim8skeptic ♦ charlie996 commented ·
@Charlie996 looks like the fuse in the bottom of the mppt might have blown.

Yank it out and test.


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JohnC avatar image
JohnC answered ·

@Charlie996

It may be set for 24V batteries. You'll need to access it's Settings screen to check.

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charlie996 avatar image
charlie996 answered ·

Today I changed the fuse in the unit and reinstalled it. The fuse was corroded and showed signs of that green residue. This is a brand new unit from Amazon. Or it’s supposed to be . I had to destroy the fuse to get it out. The top of the fuse pulled out leaving the blades stuck. I had to pull them out individually .Then put in a new one.

I’m now seeing a little power on the app but only 8 to 10 w…..Peaked at 22. I’m unsure why I’m seeing such why I’m seeing so little on the app as the panel is 80w

It’s set to 12V not 24 as it’s the default setting and I’ve not altered anything ….

Part of me says tear it out ( Again ) and return it. I’m completely unsure if it’s even working correctly. The lack of wattage showing on the app and the corroded fuse doesn’t inspire confidence..


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ff08da0c-18b0-44a1-ae1f-8fafc6a7a14f.jpeg (124.8 KiB)
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pwfarnell avatar image pwfarnell commented ·
In the screen shot above the unit is on absorption and the voltage is 14.4V which is probably the set voltage for absorption. This means that the battery is pretty full and it is the battery that limits current during absorption to stop the voltage rising above the set voltage. If you want to test it out, discharge the battery low enough that the controller works in bulk when it will charge with a higher power and the voltage below 14.4 so the battery is not the limiting factor.
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charlie996 avatar image charlie996 pwfarnell commented ·

That screenshot was taken immediately after I reinstalled. It quickly went back to “float” and the wattage on the app went down to 10…

The voltage of the battery seems to stay stable at 13.8

It’s the low wattage numbers displayed that concern me. The PV panel is 80w.

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kevgermany avatar image
kevgermany answered ·

Given the state of the fuse, I'd return it asap, for replacement.

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jetlag avatar image jetlag commented ·
I would agree. Nevertheless it woult be interessting to know what settings are set. Because we might have the same discussion in a few days when the "new" mppt charger has arrived. ;-)

To me it seem also, that the battery is full and doesn't pull any more energy. And also 13,8 might be a kind of float voltage but still the battery is full.

So please drain the battery down to 70% or something (pulling 25Ah out of it or so) and then check in pure sunshine what the charges delivers then.

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charlie996 avatar image charlie996 jetlag commented ·
Unfortunately I can’t test the device any further as on the advice above I sent it back.

Now I’m unsure whether to buy another Victron one or try a different brand ?

Can anyone advise on alternatives?

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jetlag avatar image
jetlag answered ·

Victron provides you a lot of possibilities and options other often do not offer. And if the system will grow some day, it is easy to integrate other victron parts that can "talk" to each other.

Maybe you try to get a replacement also from victron, if the behaviour is the same, then it seem to be a setting issue. If you are still not happy, you can send it back agin and chose some other manufacturer.

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charlie996 avatar image
charlie996 answered ·

Firstly many thanks for the information and help with this issue.

I’ve ordered an exact replacement on the basis Victron have such a good reputation and that this forum has been excellent and I doubt any other manufacturers have such brilliant facilities. My new 75/15 should be here mid week.

Thanks again I genuinely appreciate it..

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kevgermany avatar image kevgermany ♦♦ commented ·
Good move.

If you have any problems getting it set up correctly, please start a new question.

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nickdb avatar image nickdb ♦♦ commented ·

What is the panel's Voc?

What does the victron connect trend graph for PV voltage show?

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