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jonathon-mcalinden avatar image
jonathon-mcalinden asked

Victron Mppt 75 / 15. 0 amps and 0 Watts (at times!)

screenshot-20220328-073446-comvictronenergyvictron.jpgHello all.


I have a 200 W flexible solar panel on the roof of my campervan. It is controlled with a MPPT 75 / 15 controller. My battery is a 110 mAh lithium lifePO4 with built in BMS.


My MPPT was working fine, up until a few weeks ago and it stopped working. Currently at the moment I am getting 0 Watts and 0 Amps. The panel is producing 23 v, tested with a multimeter from the panel MC4 connectors and also on the positive and negative wires that goes into the PV + & - terminals on thr MPPT.


When I put the positive and negative wires into the MPPT terminals then the voltage drops down below the current battery voltage 13.3 v (I know this is a fully charged battery, but my SOC is 57%).


The weird thing is, some mornings I check the app and the solar has been getting around 1-3 Watts but it doesn't log it on the history tab in the app nor does it charge the battery.

It seems that the controller is always keeping the voltage down below the battery voltage at all times. When the DC to DC charger is working then the solar volts will then rise but still kept under the battery voltage which can be around 14 volts.


I am totally confused and I've been searching the Internet to try and get an answer. I hope someone in here will help me rectify this issue. Thanks


I will leave some photos of the battery settings and also a screenshot of the MPPT receiving Watts but not charging.

MPPT Controllers
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7 Answers
jonathon-mcalinden avatar image
jonathon-mcalinden answered ·

So I've found the problem. It is 100% the panel. I connected a 65w solar panel and the charger kicked in straight away.


I'm going to investigate the junction box and see if there is any corrision on the terminals.

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andy-h avatar image andy-h commented ·
How did you get on in the end.?
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jonathon-mcalinden avatar image
jonathon-mcalinden answered ·

This was the panel working this morning (it only seems to work in the mornings when I 1st log on, but it doesn't save it in the history tab?) screenshot-20220328-073446-comvictronenergyvictron.jpg


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jonathon-mcalinden avatar image
jonathon-mcalinden answered ·

The controller currently at the moment, 0 Watts and 0 Amps. The charger is off as the PV power isn't 5v above the battery voltage. screenshot-20220328-082823-comvictronenergyvictron.jpg


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guitarguy avatar image guitarguy commented ·
Have you figured this out? I have the same problem. Just happened suddenly a few days ago . I just re soldered the small jump wire connected to my panel and new connectors but it didn't work. Have 38 v coming into the controler but it only reads what the battery voltage is like yours and no amps or watts.
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guitarguy avatar image guitarguy guitarguy commented ·
And also it reads low right before sun up
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jonathon-mcalinden avatar image jonathon-mcalinden guitarguy commented ·
Still haven't found out the problem. I think it might be the panel. I am so confused.
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nickdb avatar image
nickdb answered ·

Your pv voltage needs to be 5V above the battery voltage before the mppt will turn on.

So it is behaving normally.

You need to sort your panels out so they can generate sufficient voltage to work.

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jonathon-mcalinden avatar image jonathon-mcalinden commented ·
They are giving me 23v tested at the panel, when connected to the MPPT the voltage drops?
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klim8skeptic avatar image klim8skeptic ♦ jonathon-mcalinden commented ·
You have a bad connection (high resistance) between the mppt and panel, or a bad panel.
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guitarguy avatar image
guitarguy answered ·

My problem was a bad wire connected to the panel. I had to unsolder it from the panel. Not easy. Was not ment to be repaired. Good luck

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jonathon-mcalinden avatar image jonathon-mcalinden commented ·
My next step is to look at the junction box of the solar panel and see if there is any corrision.
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klim8skeptic avatar image klim8skeptic ♦ jonathon-mcalinden commented ·

Testing a solar panel.

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jonathon-mcalinden avatar image
jonathon-mcalinden answered ·

Really strange, the battery SOC was 89% but looks like the solar panel worked and now the SOC is 99%

Confused?

screenshot-20220401-192601-comvictronenergyvictron.jpg


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andy-h avatar image andy-h commented ·
Did you get anywhere with this? Thanks
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champalimaud avatar image
champalimaud answered ·

Hi, I have the same issue. All the connections and hardware are new. Straight from solar panel I get over 20V, but if I plug positive to the Mppt (75/15) I get 13.5 volts more or less. Very strange. SO I have no watts. Did you solve? When I installed 3 days before it was not sunny but from a solar panel of 61W I got 0,5amps.

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