FLEXnetDC reset to 100% on system restart

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FLEXnetDC reset to 100% on system restart

Postby stevetull on Sat Sep 29, 2018 2:07 pm

It's a little disconcerting to know it could happen again and I may not notice. We usually run on High Battery Transfer (HBX) and draw the batteries down by 10% each day.
Yesterday morning after our system reconnected to grid power sometime during the night when I got up we were at 90% battery capacity as usual and running on grid power, all fine.
I needed to do a little work in the combiner boxes on the roof so before daybreak I powered down the system for good measure and did my work. Came back down and powered up our system and the battery monitor reported that our battery was at 100% SOC, as indicated on the Mate3s. It seems that somehow our FNDC reset itself in just powering down and then powering up our system. Not a good condition as we don't need our battery monitor lying to us.
Has this happened to anyone else? Can anyone please explain why this happened?

Thank you for any input.

-Steve
stevetull
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Posts: 87
Joined: Tue Feb 24, 2015 7:40 am
Location: Near Bastrop Texas
My RE system: FlexPower Two:
2 VFX3648, X240, 2 FM80, Mate 3s, FnDC, Hub 10
One array facing south at 30 degree tilt
One array facing southwest at 10 degree tilt
Total of 8kW
16 Fullriver AGM DC400-6 = 830Ah @ 48v
OpticRE: Paige cabin

Re: FLEXnetDC reset to 100% on system restart

Postby Mike Curran on Sat Sep 29, 2018 3:22 pm

Steve - how exactly did you "power down" your system? Because if you opened the battery breakers, your Mate would have lost power and that would've reset your FNDC when power was restored... - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
Mike Curran
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Posts: 861
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, grid-tied.

Re: FLEXnetDC reset to 100% on system restart

Postby stevetull on Sat Sep 29, 2018 3:54 pm

Hello Mike.

I always use the same de-energize procedure. Turn off all incoming AC breakers, turn off the two 175 amp inverter breakers, they say to wait 5 minutes, then turn off PV breakers and the charge controller breakers.

Re-energize sequence is the reverse.

I certainly can see how the FNDC would reset itself. What is the alternative? Looking at the wiring diagram it looks like the FNDC as well as the Mate and Hub get their power from the inverters, so leaving the 175 amp breakers closed should take care of it? So actually only opening the PV breakers will accomplish my roof work safety concern and leave all other components on.

So if that's the case, is there any frequent instance when I may need to power down entire system and cause FNDC grief that you can think of?

-Steve

Edited a few minutes later: Actually maybe only opening the ground fault charge controller breakers would take care of it?
stevetull
Forum Virtuoso
 
Posts: 87
Joined: Tue Feb 24, 2015 7:40 am
Location: Near Bastrop Texas
My RE system: FlexPower Two:
2 VFX3648, X240, 2 FM80, Mate 3s, FnDC, Hub 10
One array facing south at 30 degree tilt
One array facing southwest at 10 degree tilt
Total of 8kW
16 Fullriver AGM DC400-6 = 830Ah @ 48v
OpticRE: Paige cabin

Re: FLEXnetDC reset to 100% on system restart

Postby Mike Curran on Sat Sep 29, 2018 4:38 pm

stevetull wrote:So actually only opening the PV breakers will accomplish my roof work safety concern and leave all other components on.

So if that's the case, is there any frequent instance when I may need to power down entire system and cause FNDC grief that you can think of?

Edited a few minutes later: Actually maybe only opening the ground fault charge controller breakers would take care of it?
Two days ago I did my semi-annual tilt adjustment on my upper array (see photo).
FB_IMG_1496760253740.jpg
Since the individual MC4 connectors have to be unplugged to leave enough slack to make the adjustment, I just open the PV breakers (1st breaker from the panels) to insure I'm not unplugging the MC4's under load. I suspect that's all you need to do, also.

And no, can't think of a reason to completely shutdown my system, at least not on a routine basis. - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
Mike Curran
Forum Czar
 
Posts: 861
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, grid-tied.

Re: FLEXnetDC reset to 100% on system restart

Postby stevetull on Sun Sep 30, 2018 2:24 pm

20180930_153432 (1).jpg
20180930_153320 (1).jpg
Hello Mike.

I gave the batteries a good charge yesterday and then let them rest almost 24 hours. The DVM indicates the bank is at 51.22 volts. I'm satisfied with that as Fullriver said look for between 51 and 52 volts. I've started everything up and all looks good. Thank you for your help, and in the future I now know I only need to open the ground fault CC breakers and maybe the PV breakers to do safe roof work, but I'll still do that at night.

BTW, my array looks similar to yours. The three rows in the background are 18-older 175 watt panels facing south at a 30 degree tilt, the ones flat on the roof are 12-270 watt panels facing southwest at a 10 degree tilt that we added last year, and the ones behind the ridge are two strings supplementing each of the other arrays, 3-275 watts panels per string all facing southwest at a 15 degree tilt. We added these when we upgraded to the new Flexmax 80 charge controllers.
stevetull
Forum Virtuoso
 
Posts: 87
Joined: Tue Feb 24, 2015 7:40 am
Location: Near Bastrop Texas
My RE system: FlexPower Two:
2 VFX3648, X240, 2 FM80, Mate 3s, FnDC, Hub 10
One array facing south at 30 degree tilt
One array facing southwest at 10 degree tilt
Total of 8kW
16 Fullriver AGM DC400-6 = 830Ah @ 48v
OpticRE: Paige cabin


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