FNDC Voltage Reading Incorrect

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svsimple
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My RE system: FlexMax 60 / MATE3S / Solara 140W Panels

FNDC Voltage Reading Incorrect

Post by svsimple »

I have the following installed on my boat:

1. FM 60 solar charge controller
2. MATE3s
3. FNDC (just recently installed)
4. Balmar SmartGauge Meter
5. Bank of 12 x Firefly G31 batteries (12V system)

The Balmar SmartGauge matches the reading I get with a handheld voltage meter exactly.

The FM60 controller was consistently reading the voltage as 0.1 Volts lower than the Balmar SmartGauge and the handheld unit, so I set the Battery Voltage Calibrate to +0.1V and they now all match.

The PROBLEM is that the FNDC does not match any realistic readings. It can vary from -0.1V to -0.3V from everything else.

QUESTIONS:

1. Is there a way to calibrate the FNDC?

2. Which component determines the solar charger operation (BULK/ABSORB/FLOAT), the FM60 reading or the FNDC reading?.

My batteries require a very specific charge profile, which I believe was all working properly before the FNDC was installed. So I am concerned that if the FNDC is what determines the operation, my batteries will be damaged over time due to higher charge voltage.

3. If the answer to #2 is the FNDC, is there a way to set it up so the FNDC does not control the system, but rather only reports what is going on?

Thanks!
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Mike Curran
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My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, battery backup mode
All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: FNDC Voltage Reading Incorrect

Post by Mike Curran »

1. Calibration application note: http://outbackpower.com/downloads/docum ... p_note.pdf

2. If you search the FlexnetDC board for "calibrate" you'll find many references to this, but I think this thread answers your question #2: "Your installed FNDC has the precedence in measuring your battery voltage."
http://www.outbackpower.com/forum/viewt ... ate#p56958

3. I don't think so, at least not according to Greg's response in the thread cited above.

- Mike
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-11-10
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
svsimple
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Posts: 13
Joined: Fri Feb 15, 2019 5:56 am
My RE system: FlexMax 60 / MATE3S / Solara 140W Panels

Re: FNDC Voltage Reading Incorrect

Post by svsimple »

Thank you Mike.

I read that entire thread and from what I understood the FN-DC is reporting the temperature compensated voltage value. I assume the FM60 reports actual value like my DVM and SmartGauge do.

Is this correct? I do have the RTS connected to the MATE3s.

If this is the case, then at 21 ┬║C that would explain the FN-DC reporting 14.4V while all my other measurements are 14.5V, for example.

Do you know if this is documented somewhere with a definitive answer on how the FN-DC? These batteries are super expensive, so I want to make sure I'm not messing them up over time.

Thanks again!
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Mike Curran
Forum Emperor
Posts: 2566
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, battery backup mode
All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: FNDC Voltage Reading Incorrect

Post by Mike Curran »

I couldn't find a definitive statement about what voltage the FNDC sends to the Mate, but judging from the calibration procedure steps 8 and 9 (quoted below), I'd bet that it is the actual voltage, NOT the TC voltage, since the procedure calls for matching it to what your voltmeter reads.

8. Read battery voltage from MATE3 battery screen (seen when the BATTERY soft key is pressed)
9. Adjust trim pot (R83) until the displayed voltage of the FN-DC (from MATE3 display) matches measured battery voltage (measured between terminals 1 and 2 with DMM)


Having said that, systems with an RTS use the temperature compensated voltage for float and absorb. This app note may also help:
http://outbackpower.com/downloads/docum ... p_note.pdf
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-11-10
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
svsimple
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Posts: 13
Joined: Fri Feb 15, 2019 5:56 am
My RE system: FlexMax 60 / MATE3S / Solara 140W Panels

Re: FNDC Voltage Reading Incorrect

Post by svsimple »

Mike, thanks again for the help. I calibrated the FNDC per the instructions and now all the readings match up!
raysun
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My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
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Outback IBR3 battery enclosure
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Re: FNDC Voltage Reading Incorrect

Post by raysun »

I was interested in this carbon foam technology a couple of years ago.

I wonder how this bank of 12 blocs in parallel is holding up?
pss
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Re: FNDC Voltage Reading Incorrect

Post by pss »

After 5 years this is what I know: The fndc is a compact circuit board that has a few potentiometers on it that could adjust the voltage. But it was not designed to be calibrated. And it is a use it and throw it away board, ie. no component repair or replacement. I would say the best way to use the fndc is to fully charge your batteries by voltage and if flooded specific gravity. Power off and then power on fndc via Ethernet connection to the hub 4 or 10. Your SOC should be an accurate 100 percent which is the most important function of the fndc. If fndc voltage varies from battery terminal voltage by more than 0.2 or 0.3 on 48 volt system, ask outback to swap it out. Of course if it reads too high you maybe could put a small resister in line (just a suggestion). That's my experience with swapping them out an trying to match terminal voltage.
User avatar
Mike Curran
Forum Emperor
Posts: 2566
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, battery backup mode
All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: FNDC Voltage Reading Incorrect

Post by Mike Curran »

Of course if it reads too high you maybe could put a small resister in line 
I did that!
https://smart.tigoenergy.com/p/pZXn7SZQyO45?date=2021-11-10
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
raysun
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Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: FNDC Voltage Reading Incorrect

Post by raysun »

Mike Curran wrote: Sat Oct 09, 2021 1:26 pm
Of course if it reads too high you maybe could put a small resister in line 
I did that!
I thought that a nettlesome hack. Until I opened an FNDC and immediately lost the little (non)captive nut for the cover screw.
fcwlp
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I install and maintain grid-tied and off-grid systems in my area and consult on solar system design/operation.
Location: 80 miles NE of Phoenix at 5500'

Re: FNDC Voltage Reading Incorrect

Post by fcwlp »

raysun wrote: Sat Oct 09, 2021 1:53 pm Until I opened an FNDC and immediately lost the little (non)captive nut for the cover screw.
The POT adjustment is the easy part.
raysun
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Posts: 6531
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: FNDC Voltage Reading Incorrect

Post by raysun »

fcwlp wrote: Sun Oct 10, 2021 7:55 am
raysun wrote: Sat Oct 09, 2021 1:53 pm Until I opened an FNDC and immediately lost the little (non)captive nut for the cover screw.
The POT adjustment is the easy part.
Grrrr... yes it is. Taking the @#$@ cover off was a pain. I thought about drilling an access hole through it.
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