Understanding flexnet dc

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Understanding flexnet dc

Postby glennvtr on Sat Nov 07, 2015 1:14 am

1.Hi there I have just installed a new FNDC, I would like to understand , how could my batteries be fully charged, after a few hours of sun, and with a voltage of 54v and my SG is only at 1,21? FNDC 100%.
2.my system Is agrid tie system,I am using SOC, if I would like to use the grid and push use AC, it flicks back too inverter after 30sec or so? I can I run grid if I wanted too?
My flexnet advanced control on mate 3, is set too:
Charge termination control=no
Auto grid tie=no

My system:
2x3048
2xfm80
Mate3 version 3.11
5kw panels( with 6 hours of bright sun)
730ah opzs Hoppecke

Settings
BCF 85%
Return amps14.6
Charge voltage 57.2
Charge time 1 min
glennvtr
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Re: Understanding flexnet dc

Postby Kent Osterberg on Sat Nov 07, 2015 10:02 am

You may be dealing with more than one issue here.
First question: have the batteries been charged until charge parameters have been met since you installed the FNdc? If not, what the FNdc displays for SOC is meaningless.
Second question: have the batteries been charged until charge parameters have been met recently? If not, what the FNdc indicates for SOC is highly suspect.
If you didn't have the FNdc, what would the specific gravity of your batteries be? As you have things configured right now, the FNdc isn't responsible for the low specific gravity. What are the charge controller settings? They need to be adjusted so that the battery is charged properly.
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Re: Understanding flexnet dc

Postby blackswan555 on Sat Nov 07, 2015 10:32 am

Hi there I have just installed a new FNDC, I would like to understand , how could my batteries be fully charged
Were they fully charged when you booted the FNDC up ? It assumes they are,

how could my batteries be fully charged, after a few hours of sun, and with a voltage of 54v and my SG is only at 1,21? FNDC 100%.

They are not, At a SG of 1.21 they are around 50 to 60% SOC, Reading between the lines, If that is what you are seeing after "a few hours of Sun" You may be taking them down a bit on the low side, What is your "low" SG ?

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.
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Re: Understanding flexnet dc

Postby glennvtr on Sat Nov 07, 2015 1:18 pm

Thank you Tim and Kent

The specific gravity of these batteries are rated 1.24 @100 % charge, my battery temp here in summer is 30 deg, the abient temp is 30-35 deg, on the charts for a 100% charge according to Hoppecke South Africa is 1,23 for 100%@30 deg.

They were fully charged when I installed the FNDC/reset them, I have so much sun here that they do reach there parameters(green light blinking), just about everyday , with current settings, however early in the morning 9:30 they show 100% with SG@ 1,21, after absorbing for 4.5 hours, I have my SG @ 1.22, it's close but, whey are they showing 100% @ 10am with a SG of 1,21? They are closer to 85% according to my charts?

1.Don't know which setting to troggle to have a more accurate SOC?
2.If I set my HBX to voltage + SOC, would that give me a grid on demand? If I feel so?(different related question)

Thanks For the input.
Specially Tim, I see you have been helpful to everyone reading on the forum.
glennvtr
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My RE system: GVFX3048

Re: Understanding flexnet dc

Postby Kent Osterberg on Sat Nov 07, 2015 5:39 pm

The BCF you are using seems a little low. That would make the FNDC more susceptible to the "FNDC suddenly jumps to 100%" bug in its firmware. One way to tell if that is the problem is to simply observe the SOC every 15 minutes.
Kent Osterberg
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My RE system: SMA Sunny Boy 2500 with eight Mobil Solar Ra 180 modules


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