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FNDC +Battery Connection

Posted: Fri Feb 14, 2020 7:40 am
by provo
Once I separate my two battery strings with a breaker on each string, the FNDC batt+ wire will be on the system side (not the battery side) of those breakers, and will be disconnected whenever both breakers are off.

Will the FNDC (which I don’t have yet) lose settings if the positive battery connection goes down?

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 7:49 am
by Mike Curran
This app note http://outbackpower.com/downloads/docum ... p_note.pdf says

"Once the settings are programmed into the FN-DC, they will stay in nonvolatile memory."

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 8:20 am
by provo
Mike Curran wrote:
Fri Feb 14, 2020 7:49 am
This app note http://outbackpower.com/downloads/docum ... p_note.pdf says

"Once the settings are programmed into the FN-DC, they will stay in nonvolatile memory."
OK, but there's also this: "The measured values (Ah in/out, state of charge) will be lost if system power is lost, but the recorded values (that are transferred to nonvolatile memory) will not be lost." So that raises the question as to where that "system power" comes from, the +battery wire, or over the Cat5 cable?

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 8:50 am
by raysun
provo wrote:
Fri Feb 14, 2020 8:20 am
Mike Curran wrote:
Fri Feb 14, 2020 7:49 am
This app note http://outbackpower.com/downloads/docum ... p_note.pdf says

"Once the settings are programmed into the FN-DC, they will stay in nonvolatile memory."
OK, but there's also this: "The measured values (Ah in/out, state of charge) will be lost if system power is lost, but the recorded values (that are transferred to nonvolatile memory) will not be lost." So that raises the question as to where that "system power" comes from, the +battery wire, or over the Cat5 cable?
With the battery essentially powering everything, including the Hub, where the FNDC is getting power is a bit of a distinction without a difference. ;)

The important takeaway here is when the FNDC is power-cycled, upon restarting it sets the SoC indicator to 100% - irrespective of the battery's true State of Charge. Be sure the battery is at 100% SoC, or ignore the FNDC's readings until the battery is charged to 100% SoC.

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 9:05 am
by provo
raysun wrote:
Fri Feb 14, 2020 8:50 am

With the battery essentially powering everything, including the Hub, where the FNDC is getting power is a bit of a distinction without a difference. ;)
Duh.... :oops: Yup !!
raysun wrote:
Fri Feb 14, 2020 8:50 am

The important takeaway here is when the FNDC is power-cycled, upon restarting it sets the SoC indicator to 100% - irrespective of the battery's true State of Charge. Be sure the battery is at 100% SoC, or ignore the FNDC's readings until the battery is charged to 100% SoC.
Thanks, both of you!

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 9:11 am
by raysun
Also, in the FlexPower panels (and I assume in the GSLC or whatever DC panel is used with Radians), there is a 0.5A DC breaker between the B+ and the FNDC. If that DC disconnect is not in your BoS, a 0.5A inline fuse can be substituted.

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 9:17 am
by provo
raysun wrote:
Fri Feb 14, 2020 9:11 am
Also, in the FlexPower panels (and I assume in the GSLC or whatever DC panel is used with Radians), there is a 0.5A DC breaker between the B+ and the FNDC. If that DC disconnect is not in your BoS, a 0.5A inline fuse can be substituted.
I've got the ancient PS2 AC/DC Boxes on the big green plate :grin: ..... I'll be using a fuse, like I do now for the Trimetric.
Thanks again.

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 9:26 am
by raysun
I figured you had it covered.

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 10:57 am
by JRHill
raysun wrote:
Fri Feb 14, 2020 8:50 am
...ignore the FNDC's readings until the battery is charged to 100% SoC.
Just to add to Mr. Raysun's input, once you *know* the batteries are at 100% or as close as possible, you will need to power cycle the FNDC so it and the bank are in sync. The problem here is that the FNDC will be measuring power into and out of the respective bank. So if you have bank1 connected and verify it at 100%, bank2 may not be the same. So if you flip from one bank to the other the FNDC has no way of differentiating the two. Flipping from one to the other will render SOC to be meaningless. The closest work around to make SOC the most useful is to always keep both banks connected. But you know the banks will not charge identically so your only true gauge of SOC is by taking hydrometer readings of each cell in each bank to know how they are doing.

I believe you may already know the above and I only say it for clarity for the broader audience who comes across this thread. Multiple strings are not good for the hands-off folks.

Best,
Jijm

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 11:02 am
by raysun
Splitting the battery into two banks is an operational nightmare waiting to happen.

It requires modification of the old truism: You will ruin BOTH sets of your batteries.

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 11:05 am
by JRHill
raysun wrote:
Fri Feb 14, 2020 11:02 am
You will ruin BOTH sets of your batteries.
One guy I know like myself has enough trouble with one bank.

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 11:10 am
by raysun
JRHill wrote:
Fri Feb 14, 2020 11:05 am
raysun wrote:
Fri Feb 14, 2020 11:02 am
You will ruin BOTH sets of your batteries.
One guy I know like myself has enough trouble with one bank.
Battery banks, and wives, both sound like more would be better, but one is definitely enough.

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 11:27 am
by provo
raysun wrote:
Fri Feb 14, 2020 11:02 am
Splitting the battery into two banks is an operational nightmare waiting to happen.
It requires modification of the old truism: You will ruin BOTH sets of your batteries.
Ha Ha :lol: ... I don't actually plan on bouncing back and forth indefinitely. The question is, could I learn to live with just one string long term?, given that my consumption is so much less than I thought it would be 12 years ago. Since that might not work for me, I have to keep both strings healthy until I know. But again, this has never been a "set and forget" system!

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 12:17 pm
by JRHill
raysun wrote:
Fri Feb 14, 2020 11:10 am
...one is definitely enough.
Yeah. And you aren't married to a gulf disabled cute blond vet Army Drill Sargent++, mechanic and power plant manager and retired fed. I have lots of input to my work....

Re: FNDC +Battery Connection

Posted: Fri Feb 14, 2020 12:45 pm
by raysun
JRHill wrote:
Fri Feb 14, 2020 12:17 pm
raysun wrote:
Fri Feb 14, 2020 11:10 am
...one is definitely enough.
Yeah. And you aren't married to a gulf disabled cute blond vet Army Drill Sargent++, mechanic and power plant manager and retired fed. I have lots of input to my work....
OOORAH!