question

depalma avatar image
depalma asked

SmartSolar MPPT 100/20 does not allow starting the inverter?

I created a small solar system on my balcony, consisting of a single 300W panel, 100/20 MPPT, 200Ah LiFePO4 and 2,000W inverter - made for educational purposes.

For few weeks I have been experiencing a specific problem:

During evenings (small or no light), when the converter is off, I am not able to start it. Battery is fully charged but it acts like it was flat = no response. I feel it is the Victron battery charger causing it…

The situation is back to normal in the mornings when more Volts are generated.

Has anyone experienced the same problem? Can there be something wrong with my Victron?

An addition observation: at evenings, in the Victron app I can see the voltage fluctuating (up to few Volts), but no Amps. There is an additional note popping up and disappearing: “why is my charger switched off?”

Please help. Many thanks for help.

MPPT Controllersbattery
2 comments
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
We need some more information about your system, maybe some pictures and/or a wiring diagram.
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depalma avatar image depalma Matthias Lange - DE ♦ commented ·

Dear Matthias, Thank you for your kind response. Here is the overall picture of my system… I hope you will find it sufficient.a2c40eb2-8eaa-4766-bb20-a3470640925a.jpeg

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2 Answers
seb71 avatar image
seb71 answered ·

Check the MPPT fuse (at the bottom).

Disconnect the PV first, then the battery.


Edit:

During evenings (small or no light), when the converter is off, I am not able to start it.


Maybe I misunderstood. Which device does not start?

And which one you call "converter"?

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depalma avatar image depalma commented ·
How can I check the fuse? Shall I remove it and check visually?


By “converter” I mean the DC/AC device - this big blue boy. This one does not start during evenings. I think the starting current is 100A and battery is full, but the system just “pretends” that battery is flat during evenings…

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seb71 avatar image seb71 depalma commented ·

The MPPT fuse is probably fine. I misunderstood that the MPPT does not work at night.

Try starting the inverter without any load.

Also measure the battery voltage (with a multimeter) when the inverter starts.

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depalma avatar image depalma seb71 commented ·

This morning, when the system is back again, as you recommended, I checked with multimeter the voltage drop during the inverter start.

Battery display showed at first 13,3V, but when I switched the inverter on, voltage was erratically showing 5,8V, 8,8V, 9V then after little time it was back to normal (13,3V).

MPPT shows now 7W charging power (from 30,26V and 0,2A) - we are still in the shadow.

Shall I switch the inverter off, wait for some time and check the voltage drop again from the Victron app? This should give more precise results than multimeter.

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tom4x avatar image tom4x depalma commented ·
This indicates an issue with the battery
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depalma avatar image depalma tom4x commented ·
Could you please elaborate? The battery is 4 months old…
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tom4x avatar image tom4x depalma commented ·

You say yourself, that the battery "acts like flat" and it does not deliver any power.

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depalma avatar image depalma seb71 commented ·
Many thanks for these hints…


Here came the evening!

As you suggested, I physically removed all loads - both sockets at the inverter are empty… but it did not start, just gave a single sound and again: I can do nothing but to wait until tomorrow morning… entire system is dead, battery seems flat, indicator is turned off. Tomorrow morning all will be back, up & running as soon as there is even a small light = MPPT will wake everything up…

I will check the voltage at inverter start in few hours and revert…

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klim8skeptic avatar image klim8skeptic ♦ depalma commented ·
The display on the battery reads 13.4v? Not correct?
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depalma avatar image depalma klim8skeptic ♦ commented ·

After I attempt to switch on the inverter, there is a single (weak) beep from the device, then everything goes down.

Display on the battery shuts off, showing nothing and I am not able to switch it on. That is why I used this weird expression that “battery acts like it is flat”.
Next morning all is back to normal. Battery display shows solid Voltage.

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ben-stein avatar image ben-stein depalma commented ·
It sounds like what's happening is the startup inrush from the inverter is greater than the battery's BMS can handle. I'm guessing that you're tipping over the current limit for the battery, but with a little assistance from the MPPT (when it's got energy to provide via solar) you can charge the capacitors in the inverter and get it started.


-Ben

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depalma avatar image depalma ben-stein commented ·
Dear @Ben Stein Thank you so much for this valid comment! Would you call this a “malfunction” or is this just the way it is…? I wonder if I need to accept the situation (and stop switching off the system before evenings) or I need to act by, for example, giving up this inverter? Stay safe, Piotr
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depalma avatar image depalma ben-stein commented ·

Hello again @Ben Stein,

Thinking abt the situation again… After the whole day of charging, the battery is full and should be able to charge the capacitors, right? I am attaching the datasheet of the battery, the inrush current is 300A JLFP12-200.pdf

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jlfp12-200.pdf (8.4 MiB)
klim8skeptic avatar image
klim8skeptic answered ·

What is up with the PV breaker?

Wire colour coding changes in > out.

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depalma avatar image depalma commented ·
Thank you for noticing that! Great eyes! Cables are ok, colors were switched - I made a mistake during the I installation
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