Easysolar II shuts down PV input, although Pylontech batteries aren't full?

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fab13n asked May 26, '24

Easysolar II shuts down PV input, although Pylontech batteries aren't full?

Hello,

I have an Easysolar II with a pair of 50Ah Pylontech batteries on a boat (https://vrm.victronenergy.com/installation/72568).

Everything was working fine last year, we spent winter directly connected to the shore, but this year I get a weird behavior, which doesn't seem fixed even after updating every Victron firmware: The MPPT seems to throttle the PV input, as if the batteries were full, although they aren't. Even when I draw several kW from the batteries through the 230VAC output, the MPPT still won't accept any signigicant current.

The panels are 2 strings of 6 400W Trinasolar, and they're clearly pushed past their MPP at around 38V per panel (https://static.trinasolar.com/sites/default/files/EN_Datasheet_Vertex_DE09.pdf):

The MPPT indicates it's under external control, I guess from the Pylontech BMS through the Cerbo—I've forgotten som eof the setup details. It keeps its "Absorbption" yellow LED on, although I don't know whether it means anything under external control.

Other things I've tried to figure it out:

Switching the master/slave roles of the Pylontech batteries doesn't help;
Shorting the PV panels at the end of the cable, where they normally connect to the Easysolar, passes a normal amount of current (several amps, I'm not docked under direct sunlight;
Voltage reading from the Easysolar seem accurate within 1%;
Battery charging from shore through the Multiplus work fine.

I don't know where to look next :-(

Pylontech EasySolar All-in-One

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Answer 1 · 2024-05-26T17:38:55Z

Alexandra answered · May 26 at 05:38 PM

@fab13n

If you disconnect the comms of the mppt from the gx (reprogram/reset) does it work as a dumb pv charger?

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Alexandra ♦ commented · May 29 at 03:39 PM

@fab13n

Your settings are not correct for Pylontec.

Use 52v abs and 51v float. It is stated as such in the online manual.

The batteries via DVCC are probably what is stopping the charge

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Answer 2 · 2024-05-27T10:05:51Z

fab13n answered · May 27 at 10:05 AM

@Alexandra when I disconnect the VE.Bus cable and power cycle, I get the following (through bluetooth on the MPPT):

At the battery, 52.95V and 0.00A;
At the PV panels, (37.4 × 6)V, i.e. pretty much +∞ impedance according to the curves above;
settings: charger enabled in ON, absorption voltage = 56.80V, float voltage = 54V;
state == "Float".

That looks wrong indeed!

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kevgermany ♦♦ commented · May 27 at 11:40 AM

What are the settings on the charger? Your voltage for 48V Pylontechs is high.

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fab13n kevgermany ♦♦ commented · May 29 at 02:32 PM

Those are the settings, when disconnected from VE bus:

And here's the corresponding monitoring view:

Notice the discrepancy between being at 52.95V < 54V yet being in "Float" mode...

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Alexandra ♦ fab13n commented · May 29 at 03:40 PM

Bms controlled - yes. The batteries are telling the mppt to stop charge. 54v is their absolute max voltage if you check in the manual. But even then that is not where you want them to charge to.

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fab13n Alexandra ♦ commented · May 31 at 09:48 AM

I unplugged the VE.direct to get the MPPT out of external control, as suggested above for troubelshooting. Indeed, I forgot to adapt the voltage settings. But setting them to 52V absorption & 52V floating changes nothing...

...and here's something noteworthy: according to Victron Connect, the MPPT sees 54V at the battery poles, while my voltmeter (at the MPPT contacts), the battery controller and the Multiplus all agree they're currently at 49V!

Could that be a blown fuse somewhere in the MPPT? Something serviceable?

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Answer 3 · 2024-05-27T20:59:51Z

klim8skeptic answered · May 27 at 08:59 PM

@fab13n The panels are 2 strings of 6 400W Trinasolar, and they're clearly pushed past their MPP at around 38V per panel.

Even at 25c a string of 6 will give an array Voc of 247.2v. Too high for a 250v mppt.

Victron mppt calculator.

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Answer 4 · 2024-05-29T14:37:25Z

nickdb answered · May 29 at 02:37 PM

Why are you using a victron smart lithium profile on a pylon battery? Read the docs, program a custom lithium profile that matches the documented pylon spec.

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Answer 5 · 2024-05-31T09:52:26Z

fab13n answered · May 31 at 09:52 AM

Update: the MPPT sees 54V at the battery poles (according to Victron Connect over Bluetooth), whereas in reality there's about 49V, as measured by the Multiplus, and the Pylontech BMS, and my voltmeter.

When the MPPT is disconnected from the GX, and setup as suggested by the doc (52V absorption, 51V floating), it logically goes into floating.

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