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leonb avatar image
leonb asked

MPPT just stops charging, battery not full

Hi,

I installed a Multi II 5kVA GX, 15 x 330W panels (3 series, 5 parallel), 150-100 Smartsolar MPPT and a Freedom Won LifeP04 battery. System works perfectly and battery most days battery get charged fully, and loads mostly covered. The panels run into a 5 in, 1 out combiner box, Cable run from combiner box to MPPT is approx 8m and I used 6mm square alu solar cable.

What is weird, is that the MPPT will sometimes just stop working, Just shows 0Watts, even when battery is at say 85%. I can see the expected voltage on the MPPT but no amps. After a good nights rest it ill be back and work like expected, just to stop again at some point the next day?

I have gone thru the following:

1. Updated to latest software

2. Checked all connections, they seem fine.

3. Double checked cable sizing, and according to my app, I am all withing 5% or less tolerance.

I have never experienced something like this and honestly dont know where else to trouble shoot? Any assistence will be appreciated.

Regards



MPPT SmartSolar
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3 Answers
Paul B avatar image
Paul B answered ·

The mppt goes from Bulk to absolution when the set-point voltage is reached it then holds absorption for the set time period and then goes to float voltage. (have these been set correctly and or for the correct battery type

This is NOTHING to do with your SOC Reading. its all to do with the voltage setting that have been set in the MPPT unit.

also depending on cable size there MAYBE a volt drop between the MPPT unit and the battery connection if the wires are undersized. to check this , then when the solar Victron MPPT unit is running at max amps check the voltage at the MPPT units Bat connections and then check at the Battery. both readings should be the same, or very close.

if they are not then increase the battery connection wire size

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leonb avatar image leonb commented ·

Thanks Paul,

Yea, all settings in MPPT checked, and as per Victron/ FreedomWon on specs.(https://www.victronenergy.com/live/battery_compatibility:freedomwon)

What I meant is that I see voltage, or expected voltage on the MPPT via the app, but zero amps. I have not spent time at the installation to watch it carefully. (Time for us installers is precious as you know)

Strangely, if it was cable sizing it will surely fail at max amps? or when sun is at peak, which it is not doing, failure is random, and MPPT only comes back next morning, after a good night's rest.?

Strangest thing...

Cheers


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klim8skeptic avatar image klim8skeptic ♦ leonb commented ·

(Time for us installers is precious as you know)

Perhaps you could leave some monitoring equipment connected for a month?

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Paul B avatar image Paul B leonb commented ·

To help any more you will need to give pacific voltages as 85% is of no real help. I would need to no the panel pacific's and a diagram of the string setups and voltages,

I cant see it being the MPPT unit, its more likly to be over voltage of the PV strings causing the MPPT to shut down , this is just a guess

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Trina avatar image
Trina answered ·

IF it is always at 85% maybe your ah is set wrong and the BMS is responsible? You would have SOME variation on the PV and MPPT side of things otherwise right?

The other thing: my system would stop "harvesting" when I had in advertently met two criteria: wrong ah/capacity and not used enough power from.the batteries the night before.

Check your MPPT profiles and verify the BMS isn't responsible?

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rolfniem avatar image
rolfniem answered ·

Hi Leon, I wonder if you ever solved this problem?

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