Did not achieve full absorb time following grid outage

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Did not achieve full absorb time following grid outage

Postby Mike Curran on Tue Nov 07, 2017 12:38 pm

We just experienced a rare, lengthy grid outage (for us, anyway - 30 hours) and my batteries ended at 74% SOC (per FNDC), about 1.255 (est'd - last taken when they were at 78% SOC: 1.265 SG). When the grid came back on after midnight, my two inverters immediately went into bulk mode, as expected. However, it appears that they did not stay at the absorb voltage setting for the programmed absorb time of 3.5 hours.
Bulk cycle after midnight.JPG


FNDC is programmed as follows:
Charged voltage: 29.1V
Charged return amps: 35A
Charged time: 5 minutes
Charge factor: 90%

Auto Grid-Tie control is "enabled", which allows the charge controllers (in my case, MX60 & FM80) to complete a charge cycle at the beginning of each day before the system begins selling. It prevents the batteries from remaining at or below the Sell voltage for extended periods without receiving a full charge.

Charge termination control is "disabled", which means the FNDC should not interfere with the charging process when it's been initiated by the inverters (as I understand it, anyway).

I took a specific gravity reading this morning after all this and got 1.280 on my pilot cell, so it appears my battery got back to 100%. My question is, is my system working as it should? Because it seems like I'm missing something - why didn't the GVFX's get a chance to complete the full absorb time? Or should they have?

Thanks in advance!
Mike Curran
OutBack Guru
 
Posts: 334
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback: 8 (2x4) Evergreen 180's into one MX60, 6 (2×3) ALEO S79-300's into one FM80, 2 grid-tied GVFX3524's classic stacked for 120/240VAC, 12 Surrette/Rolls 2V x 1766Ah, Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar: 30 (2x15) 235W panels with Enphase M215 microinverters. 6,450 nameplate watts AC, grid-tied.

Re: Did not achieve full absorb time following grid outage

Postby petertearai on Tue Nov 07, 2017 2:24 pm

im off grid .. so not experienced with your set up . But absorb time on my set up can be terminated early with the absorb end amps setting .
2220 pv. fm80. 4times rolls 450 ah 24 volts. victron battery monitor. outback fxr 2000 watt inverter
petertearai
OutBack Guru
 
Posts: 314
Joined: Fri Aug 06, 2010 4:35 pm
Location: NewZealand North Island
My RE system: 2220 watt pv, fm80, outback fxr 2000 watt inverter. Rolls s600 times 4 24 volt system victron battery moniter. optics RE

Re: Did not achieve full absorb time following grid outage

Postby Mike Curran on Tue Nov 07, 2017 4:10 pm

That could be it. When absorb stopped, voltage had reached 29.1 and charge current was below 35A. Thanks!

Edit: Here's a spreadsheet from an Optics data report on the night (early a.m.) the absorb cycle occurred, following grid restoration. Note the last 15 minute average current reports as 50A, not really below my 35A absorb limit (unless there was a brief 35A period near the end of that 15 minute period). Comments?
20171108_211321.jpg
Mike Curran
OutBack Guru
 
Posts: 334
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback: 8 (2x4) Evergreen 180's into one MX60, 6 (2×3) ALEO S79-300's into one FM80, 2 grid-tied GVFX3524's classic stacked for 120/240VAC, 12 Surrette/Rolls 2V x 1766Ah, Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar: 30 (2x15) 235W panels with Enphase M215 microinverters. 6,450 nameplate watts AC, grid-tied.

Re: Did not achieve full absorb time following grid outage

Postby blackswan555 on Thu Nov 09, 2017 8:12 pm

I must say there are some strange readings in there, But I do not think it was end amps, If you look at the drop over the last 3 readings, At absorb they drop a similar ish amount each 15 mins, I can not think they would drop twice as much that quickly,,,

But, The weird thing about it all is you measured SGs and there were 100%, So even though you only got 45 ish mins absorb (after nearly 7 hrs of charge) You were full,

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
blackswan555
OutBack Emperor
 
Posts: 2516
Joined: Sat Aug 30, 2008 5:50 am
Location: Ibiza Spain,
My RE system: Other peoples, VFX "E" versions, FLA`s, Generators.


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