FNDC Soc vs Volts

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sodamo
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FNDC Soc vs Volts

Post by sodamo » Mon Sep 14, 2020 10:25 am

I always assumed that the relationship was pretty much straight line as per the SimpliPhi chart, 100% = highest, lower voltage = lower %.

Not so according to OpticsRE report. Highest voltage did not = highest SOC, lowest SOC did not = lowest voltage.
What am I missing?

Grrrr, forum wont let me post pics, HTTP error.
David
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raysun
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Re: FNDC Soc vs Volts

Post by raysun » Mon Sep 14, 2020 11:15 am

I've been watching a SimpliPhi installation for a while now, and have concluded the relationship between voltage and SoC is not as simple as advertised, especially under load.

Compounding this is the fact the FNDC is geared toward Lead Acid, and Lithium behaves differently.

In the beginning, charging was set to Absorb: 54.4V @ 1H. This lead to all manner of confusing readings. It was switched to 56.4V @ 0.1H, and the readings "dialed-in" quite neatly.

I'm given to ignoring SoC during charging, and watching Net Corrected Battery AH. At Bulk charge to 56.4V, SoC has been hitting 99% just as NCB-AH = 0 (or within a few AH of 0).

Once the FNDC hits 100%, usually immediately after Float stage begins, the SoC and AH discharge seem to agree with the entered battery capacity.

Voltage, on the other hand, varies a good bit with load. Not as much as a Lead Acid battery, but more than the "flat line" graphs tend to imply.

The FNDC's tracking seems to drift during several partial charge/discharge cycles, and I haven't been tracking the system long enough to capture data to this effect, nor have there been open circuit voltage measurements taken, and if they were, I'd still have no idea how they would relate to SoC. As such, IMO, SoC is fairly accurate from 100%, but isn't reliable when left adrift for several days.

I'm installing a Phi battery next month, and will configure to charge to 56.4V daily. I will tend to look at voltage only during charging, and SoC/AH during discharge.

sodamo
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Re: FNDC Soc vs Volts

Post by sodamo » Mon Sep 14, 2020 11:47 am

Thanks Raysun. I’ll take a look later, have mowing to do. Currently I’m set at 55.2/1hr. Think I came to this after dialog with Greg on Kauai. Maybe he’ll chime in.

Casual observation I wasn’t concerned, the OpticsRE display graphs looked good to me when I’d periodically check. What caused me to pull the report was I have an online friend in Ca that just had a system installed and he want’t to determine Volts vs Soc for his generator AGS. Has a different brand lithium. His installer doesn’t like the FNDC so didn’t hook it in. His plan is to use a Trimetric and try to determine the volt vs soc line. I keep encouraging him to join the forum but he hadn’t yet.

I think load is a definite factor, but no way do I intend to just shut everything down. Guess that may be a grid tied option or if I wanted to run generator extensively.

How are you tracking Ah as they don’t show up on the report.
David
Please visit http://vacation.ninolehawaii.com

raysun
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Re: FNDC Soc vs Volts

Post by raysun » Mon Sep 14, 2020 12:07 pm

sodamo wrote:
Mon Sep 14, 2020 11:47 am
Thanks Raysun. I’ll take a look later, have mowing to do. Currently I’m set at 55.2/1hr. Think I came to this after dialog with Greg on Kauai. Maybe he’ll chime in.

Casual observation I wasn’t concerned, the OpticsRE display graphs looked good to me when I’d periodically check. What caused me to pull the report was I have an online friend in Ca that just had a system installed and he want’t to determine Volts vs Soc for his generator AGS. Has a different brand lithium. His installer doesn’t like the FNDC so didn’t hook it in. His plan is to use a Trimetric and try to determine the volt vs soc line. I keep encouraging him to join the forum but he hadn’t yet.

I think load is a definite factor, but no way do I intend to just shut everything down. Guess that may be a grid tied option or if I wanted to run generator extensively.

How are you tracking Ah as they don’t show up on the report.
I wish there was an Optics switch between SoC and Corrected Net Battery AH. To see the latter figure, I navigate to Device Map - FNDC - Status and scroll to the Charge Factor section at the bottom of the page.

Locally, it can be seen on the Mate's web server on the landing page in the Battery Charge section.

sodamo
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4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
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Re: FNDC Soc vs Volts

Post by sodamo » Mon Sep 14, 2020 3:28 pm

So you do this manually individually? Was hoping for some historical data dump of sorts.
David
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raysun
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Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: FNDC Soc vs Volts

Post by raysun » Mon Sep 14, 2020 4:21 pm

sodamo wrote:
Mon Sep 14, 2020 3:28 pm
So you do this manually individually? Was hoping for some historical data dump of sorts.
I've been tracking it daily. Not that it needs tracking all the time, but for the purposes of evaluating battery/charging behavior, it appears to be a good metric.

My interest is to identify the simplest charging protocol for best utilization/cycle life. Also, identifying how and when the FNDC SoC value is accurate and useful.

sodamo
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Posts: 838
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My RE system: Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280 & 16 Phono 250 in 48 volt array (fixed) 14080w
Radians GG8048/GS4048 w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
12 SimpliPhi 3.8
14Kw Kohler 14RESA Propane

Charging Only
2FX3048T
Hub
FNDC. - shared shunt feeds from Radian FNDC
Mate 3s
10Kw MEP 803a Military gen

Honda EU7000i

Davis VantagePro2 Wx Station
On line at: https://www.wunderground.com/dashboard/pws/KHININOL2
Location: Ninole, Hi

Re: FNDC Soc vs Volts

Post by sodamo » Mon Sep 14, 2020 5:36 pm

Looking forward to your findings, Raysun.
I think your charging value 56.4 is toward lower end of SimpliPhi’s warranty 10% Soc unless you have better info.
David
Please visit http://vacation.ninolehawaii.com

raysun
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Re: FNDC Soc vs Volts

Post by raysun » Mon Sep 14, 2020 11:22 pm

There have been several charging recommendations between Outback and Simpliphi.

I'm referencing the Phi Outback integration guide rev. 042920. It specifies Outback controllers Absorb 56.4V @ 0.1H. It doesn't distinguish between 80% and 90% DoD as other docs.

Phi OB Integration guide Rev101918 lists 56V @ 0.1H for 80% DoD and 57.6V @ 1.0H for 90% DoD.

I participated in a Phi webinar on Charging and SoC in which the presentor said the 3.8 class battery could be charged to 57V without issue for 80% DoD.

You may wish to confirm with Phi tech support.

sodamo
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My RE system: Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280 & 16 Phono 250 in 48 volt array (fixed) 14080w
Radians GG8048/GS4048 w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
12 SimpliPhi 3.8
14Kw Kohler 14RESA Propane

Charging Only
2FX3048T
Hub
FNDC. - shared shunt feeds from Radian FNDC
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10Kw MEP 803a Military gen

Honda EU7000i

Davis VantagePro2 Wx Station
On line at: https://www.wunderground.com/dashboard/pws/KHININOL2
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Re: FNDC Soc vs Volts

Post by sodamo » Mon Sep 14, 2020 11:38 pm

Hmmm, my references may be out of date.
Could you got latest.
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David
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provo
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Re: FNDC Soc vs Volts

Post by provo » Tue Sep 15, 2020 6:08 am

sodamo wrote:
Mon Sep 14, 2020 10:25 am

Grrrr, forum wont let me post pics, HTTP error.

The workaround I've found for that is to login without using the auto-fill feature. If I let it log me in with auto-fill, I can't post large attachments. If I manually fill in my login name and password, the page that opens up is non-secure, and allows the posting of large attachments.

raysun
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Re: FNDC Soc vs Volts

Post by raysun » Tue Sep 15, 2020 7:31 am


sodamo
Forum Czar
Posts: 838
Joined: Mon Apr 03, 2006 1:55 am
My RE system: Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280 & 16 Phono 250 in 48 volt array (fixed) 14080w
Radians GG8048/GS4048 w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
12 SimpliPhi 3.8
14Kw Kohler 14RESA Propane

Charging Only
2FX3048T
Hub
FNDC. - shared shunt feeds from Radian FNDC
Mate 3s
10Kw MEP 803a Military gen

Honda EU7000i

Davis VantagePro2 Wx Station
On line at: https://www.wunderground.com/dashboard/pws/KHININOL2
Location: Ninole, Hi

Re: FNDC Soc vs Volts

Post by sodamo » Wed Sep 16, 2020 10:43 am

Thanks Raysun. I updated my settings to those guidelines last night. No clue what changes I will see if any. 😁
David
Please visit http://vacation.ninolehawaii.com

raysun
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Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: FNDC Soc vs Volts

Post by raysun » Wed Sep 16, 2020 10:54 am

You might see a more straight-forward charging curve.

I'd be interested in seeing the Cycle Charge Factor after a couple of cycles. (FNDC status screen in the bottom of the status page in the device map.)

My sense of it, is this "Bulk until full" charging scheme will get the battery to > 95% SoC, which is fine with me. The 100% charging schemes are hard on lithium cells, IMO.

I've noticed that the FNDC hits 100% during Float, if not at the end of the Bulk/"Absorb" cycle.

Days Since Charged Parameters Met will eventually equal infinity. ;) This charging scheme does not drive the battery over the cliff-edge of rapid current decline at full charge, so the published Charged Return Amps are never approached.

sodamo
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Posts: 838
Joined: Mon Apr 03, 2006 1:55 am
My RE system: Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280 & 16 Phono 250 in 48 volt array (fixed) 14080w
Radians GG8048/GS4048 w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
12 SimpliPhi 3.8
14Kw Kohler 14RESA Propane

Charging Only
2FX3048T
Hub
FNDC. - shared shunt feeds from Radian FNDC
Mate 3s
10Kw MEP 803a Military gen

Honda EU7000i

Davis VantagePro2 Wx Station
On line at: https://www.wunderground.com/dashboard/pws/KHININOL2
Location: Ninole, Hi

Re: FNDC Soc vs Volts

Post by sodamo » Thu Sep 17, 2020 11:14 am

Interesting 1st day observation. As you said, flatter curve. First day in long time my charge didn’t totally replace my useage 19 vs 22 kwh, with SOC topping out at 87%. Wasn’t home all day so maybe other factors, but still a surprise.
David
Please visit http://vacation.ninolehawaii.com

raysun
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Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: FNDC Soc vs Volts

Post by raysun » Thu Sep 17, 2020 12:24 pm

sodamo wrote:
Thu Sep 17, 2020 11:14 am
Interesting 1st day observation. As you said, flatter curve. First day in long time my charge didn’t totally replace my useage 19 vs 22 kwh, with SOC topping out at 87%. Wasn’t home all day so maybe other factors, but still a surprise.

The charging profile is bulk for essentially 99% of the cycle so there's no inherent current limiting by the battery chemistry or by the charge controllers, unless, of course, CC-Battery-Current Limit or Mate-Global Charge-Maximum Battery Charge are set/enabled.

The PV gods messing with you? "Hey! He made a system change. Let's make a weather change to go with." 😉

I'm given not to believe FNDC partial SoC during charging. For starters, its unlikely the SoC during discharge is computed correctly for LiFePo4. The Puekert's exponent used is for Lead Acid, and it would overestimate discharge unless the FNDC 'learns' otherwise, and I'm not aware that it does. For charging, the reverse is in play with Charge Factor, but at least that's a settable value.

Tracking the raw charge in / charge out numbers is a bit more straight-forward, but even then THE FNDC reports "Corrected Net Battery" AH/kWH. Corrected how? I've never found a reference to a formula or equation.

I'm a bit tempted to put a "dumb" current counter on with the FNDC. I've resisted the notion so far, as to avoid the "two watches" condundrum: "A man with a watch always knows what time it is. A man with two watches never knows what time it is." I may slog down that path, though, just to envision the delta.

Batteries, fun! Let us know how today goes.

provo
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Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: FNDC Soc vs Volts

Post by provo » Thu Sep 17, 2020 3:16 pm

raysun wrote:
Thu Sep 17, 2020 12:24 pm

Tracking the raw charge in / charge out numbers is a bit more straight-forward, but even then THE FNDC reports "Corrected Net Battery" AH/kWH. Corrected how? I've never found a reference to a formula or equation.
From some notes I made when I first tackled this question a few months back:


"The Corrected NET Battery value (in the Charge Factor area of the Status page of the FNDC Device Map in OpticsRE) is calculated from the values for Historical Removed from Battery and Historical Returned to Battery on the Shunt A page of the FNDC Device Map. Historical means “since the most recent start of discharging”, which in my system is shown on Shunt A.

The Charge Factor I have entered (0.84 at this time) is used to derate the Historical Returned Ah’s. For example, at one point today I saw Historical Removed at 61Ah, and Historical Returned at 69Ah. Derating the returned Ah by 0.84 gives 58Ah, and combining 61Ah removed with 58Ah returned gives -3Ah Corrected NET Battery, which was the value displayed."


I'm guessing if you used the charge efficiency for Simpliphi's (is it 98%?) the same formula would work....

raysun
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Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: FNDC Soc vs Volts

Post by raysun » Thu Sep 17, 2020 3:35 pm

provo wrote:
Thu Sep 17, 2020 3:16 pm
raysun wrote:
Thu Sep 17, 2020 12:24 pm

Tracking the raw charge in / charge out numbers is a bit more straight-forward, but even then THE FNDC reports "Corrected Net Battery" AH/kWH. Corrected how? I've never found a reference to a formula or equation.
From some notes I made when I first tackled this question a few months back:


"The Corrected NET Battery value (in the Charge Factor area of the Status page of the FNDC Device Map in OpticsRE) is calculated from the values for Historical Removed from Battery and Historical Returned to Battery on the Shunt A page of the FNDC Device Map. Historical means “since the most recent start of discharging”, which in my system is shown on Shunt A.

The Charge Factor I have entered (0.84 at this time) is used to derate the Historical Returned Ah’s. For example, at one point today I saw Historical Removed at 61Ah, and Historical Returned at 69Ah. Derating the returned Ah by 0.84 gives 58Ah, and combining 61Ah removed with 58Ah returned gives -3Ah Corrected NET Battery, which was the value displayed."


I'm guessing if you used the charge efficiency for Simpliphi's (is it 98%?) the same formula would work....
Awesome! Thanks for the correction. I'll have to start applying that to my readings.

sodamo
Forum Czar
Posts: 838
Joined: Mon Apr 03, 2006 1:55 am
My RE system: Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280 & 16 Phono 250 in 48 volt array (fixed) 14080w
Radians GG8048/GS4048 w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
12 SimpliPhi 3.8
14Kw Kohler 14RESA Propane

Charging Only
2FX3048T
Hub
FNDC. - shared shunt feeds from Radian FNDC
Mate 3s
10Kw MEP 803a Military gen

Honda EU7000i

Davis VantagePro2 Wx Station
On line at: https://www.wunderground.com/dashboard/pws/KHININOL2
Location: Ninole, Hi

Re: FNDC Soc vs Volts

Post by sodamo » Thu Sep 17, 2020 4:00 pm

Provo, I see you list a trimetric in your profile. Could you explain where it is in your system and how you use it?
David
Please visit http://vacation.ninolehawaii.com

provo
Forum Czar
Posts: 525
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: FNDC Soc vs Volts

Post by provo » Thu Sep 17, 2020 4:38 pm

sodamo wrote:
Thu Sep 17, 2020 4:00 pm

Provo, I see you list a trimetric in your profile. Could you explain where it is in your system and how you use it?
I only have one shunt, between the battery and everything else. The shunt is the 500A 50mV that came with the Trimetric, and the FNDC sense leads are connected under the same screw heads as the Trimetric leads.

I was worried that the two meters on one shunt might change the readings some, but the values were typical of what I'd always seen, and they agree with each other, so I think it's OK.

I visit my system in the basement many times a day, and I find the Trimetric easier to read, and easier cycling through the various parameters, than the FNDC display on the Mate. (Old eyes, you know.) But upstairs, of course, it's all FNDC via Optics.

sodamo
Forum Czar
Posts: 838
Joined: Mon Apr 03, 2006 1:55 am
My RE system: Totally off grid - Hamakua side, Big Island, Hi

36 Trina 280 & 16 Phono 250 in 48 volt array (fixed) 14080w
Radians GG8048/GS4048 w GSLCs
4 FM 80 charge controllers
Hub 10.3
FNDC w/3 shunts
Mate 3s
OpticsRE - MMKL - Ninole Hi
12 SimpliPhi 3.8
14Kw Kohler 14RESA Propane

Charging Only
2FX3048T
Hub
FNDC. - shared shunt feeds from Radian FNDC
Mate 3s
10Kw MEP 803a Military gen

Honda EU7000i

Davis VantagePro2 Wx Station
On line at: https://www.wunderground.com/dashboard/pws/KHININOL2
Location: Ninole, Hi

Re: FNDC Soc vs Volts

Post by sodamo » Thu Sep 17, 2020 4:47 pm

Interesting

I have an old 48v Xantrex battery monitor that was originally installed in my FX system. Was thinking I might install that shunt right at the battery combiner negative where the Outback connects.

Have a friend with a recently OB system, 2 Gs8048s with API lithiums that intends to install a Trimetric to determine SOC/Voltage. for his AGS settings
David
Please visit http://vacation.ninolehawaii.com

provo
Forum Czar
Posts: 525
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: FNDC Soc vs Volts

Post by provo » Thu Sep 17, 2020 5:08 pm

sodamo wrote:
Thu Sep 17, 2020 4:47 pm

Have a friend with a recently OB system, 2 Gs8048s with API lithiums that intends to install a Trimetric to determine SOC/Voltage. for his AGS settings
One nice thing about the Trimetric is that the SOC is rounded up or down rather than truncated like the FNDC does. Trivial really, because the amp-hour reading is much more accurate anyway, but that truncating has always bugged me!

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