System shuts off at night when SOC in in the 70% range

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merlingrant
Forum Junior Member
Posts: 2
Joined: Sun Dec 01, 2019 1:41 pm
My RE system: Flexmax 80
Mate 2
Flexware FX3048T
FNDC
8 AGM batteries manufactured by LEOCH model # LDC6-224-GC2 (48 volts)
Nine 300 watt panels

System shuts off at night when SOC in in the 70% range

Post by merlingrant » Sun Dec 01, 2019 1:59 pm

Aloha. I am completely off grid in rural Hawaii. My system shuts off a couple hours after sunset even though the SOC is in the high 70% range. The Leoch LDC6-224-GC2 AGM batteries I utilize are only few months old. If I power cycle the main breaker on the inverter at night, the power is temporarily restored. Yet, if I power cycle the inverter at the first sign of any sunlight, the power works for the day. Also, the system seems to be stuck in snooze mode even if I force bulk. The currents settings are the ones that Outback Technical support had me enter when I was on the phone with one of their helpful and kind people. Regardless, It is possible the FNDC is reading a 100% SOC when the battery is not actually at 100%. (that is speculation on my part & I am not sure if a 100% reading on the FNDC would even stop the charging of the batteries) Regardless something is off and the power shuts off after the Hawaiian sun goes down leaving us in the dark. Maholo in advance for any help!
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Kurt Lundquist
Alpha Energy Engineering
Posts: 1389
Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: System shuts off at night when SOC in in the 70% range

Post by Kurt Lundquist » Mon Dec 02, 2019 9:11 am

To calibrate the SoC you need to have the proper charge settings, FNDC settings, and the system has to run through at least 1 full charge cycle.

From your description of events, it sounds like the system is shutting the inverter output off due to low battery voltage. When you power cycle the inverter it resets the low battery error thus providing you with power for a brief period of time.

Next time this happens I suggest you check the error on the Mate before cycling power. If my theory is correct you will see a screen that shows "View Error". Press that button, then press DOWN until you see a YES to find the active error.

What are your charge settings?

What are the FNDC charged battery settings?

Do you use a generator to charge or is this 100% solar via the FM80 charge controller?

How power (kWh) do you use daily on average?

I'd say you need at least 5 sun hours per day to get daily average use of 2-4kWh from your system. Your nighttime loads probably need to be <75W per hour.
merlingrant wrote:
Sun Dec 01, 2019 1:59 pm
Also, the system seems to be stuck in snooze mode even if I force bulk.
This typically means the FM80 does not have enough input power from the PV array to harvest power. By default the FM80 stops harvesting PV when there is <.6A power from the array. You can lower it down to .2 A in the controller advanced menu.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

merlingrant
Forum Junior Member
Posts: 2
Joined: Sun Dec 01, 2019 1:41 pm
My RE system: Flexmax 80
Mate 2
Flexware FX3048T
FNDC
8 AGM batteries manufactured by LEOCH model # LDC6-224-GC2 (48 volts)
Nine 300 watt panels

Re: System shuts off at night when SOC in in the 70% range

Post by merlingrant » Wed Dec 04, 2019 12:15 pm

You are right Kurt. It’s a low voltage error & we are off grid with no generator at the moment.

SandyP
Forum Guru
Posts: 321
Joined: Tue Jun 21, 2011 4:44 am
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2)
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset
Location: Victoria, Australia

Re: System shuts off at night when SOC in in the 70% range

Post by SandyP » Wed Dec 04, 2019 6:30 pm

merlingrant wrote:
Sun Dec 01, 2019 1:59 pm
....Regardless, It is possible the FNDC is reading a 100% SOC when the battery is not actually at 100%. ....
Yes, As Kurt mentioned the FNDC "assumes" the battery bank is at 100% SoC when you connect it up. If your batteries were not fully charged when either the FNDC or your batteries were installed then you need to disconnect the FNDC and allow your system to fully charge your batteries before reconnecting the FNDC - do this ASAP!

From their application note : http://outbackpower.com/downloads/docum ... p_note.pdf

FLEXnet DC Initialization:
Since the FN-DC assumes that the batteries are fully charged when it is initially turned on, the battery
bank must be fully charged prior to turning on the FN-DC. Use the battery manufacturer’s instructions on
how to commission and fully charge the battery bank to bring it to a full state of charge. This step may
take several days depending on the system and the type of battery. Failure to take this critical step will
result in a chronically undercharged battery and therefore a reduced performance and a reduced life.

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