FNDC Wiring question... SOC dropping

An area for discussing the OutBack FLEXnet DC product.

Moderators: OutBack, OutBack Moderator Team

FNDC Wiring question... SOC dropping

Postby Jake33 on Thu Sep 07, 2017 9:29 am

I recently updated some of the components of my system adding a flexnet dc, my problem is my SOC keeps dropping and when I am getting sun it just stays the same until its out of the sun. The system is at a remote system in the mountains so I probably wont be back for a couple weeks. The system is charging the batteries just fine and I currently have 6 half watt nightlights plugged in and my internet router and that's all. I just think I have it wired wrong. I attached a picture I modified to see if this is the correct way to wire in the fndc and shunts. This is how its currently wired; the battery negative bus bar on shunt b is on the battery side of the shunt and the battery negative for the charge controller (shunt c) comes from the bus bar on shunt b. Also the bus bar on the shunt between the battery and the inverter has both battery negatives and grounds going to it, I believe that is incorrect.

Thanks or the help

KRAMER SOLAR WIRING.jpg
Jake33
Member
 
Posts: 5
Joined: Tue Aug 15, 2017 5:06 pm
Location: Council, ID
My RE system: 48v, 8 X L16RE-B, Mate 3, FM60, FX2548,FNDC, 6 X 150w panels

Re: FNDC Wiring question... SOC dropping

Postby Mike Curran on Thu Sep 07, 2017 3:48 pm

First of all, don't trust your FNDC SOC readings without taking some specific gravity readings on your batteries. That's the very best to way to determine SOC. I suspect you're going to find your battery is okay (but that remains to be seen, of course).

Since the FNDC uses flow through those shunts to determine SOC, it's very possible your negative wiring may not be right. Your W/D shows a negative wire from your FM60 charge controller (CC) going to shunt C, and another negative wire from the CC to the battery negative bus. Since your diagram indicates you have an internal jumper between these two points inside the CC, you shouldn't need that (second) wire direct from the CC to the negative bus. Although it seems like the CC current flowing through that 2nd wire should be accounted for by your shunt B, I'd remove it - it's not needed. Plus it's making your FNDC give an incorrect accounting of what your CC current is.

Here's a photo of my shunt wiring - Hope it's helpful. And I hope all this isn't more confusing than helpful. - Mike
1504824200368-7025424.jpg


PS After posting this I noticed my drawing footnote "*currently connected to neg. bus". Ignore that, it's connected as shown, to my shunt B.
Mike Curran
OutBack Guru
 
Posts: 264
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback: 8 (2x4) Evergreen 180's into one MX60, 6 (2×3) ALEO S79-300's into one FM80, 2 grid-tied GVFX3524's classic stacked for 120/240VAC, 12 Surrette/Rolls 2V x 1766Ah, Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar: 30 (2x15) 235W panels with Enphase M215 microinverters. 6,450 nameplate watts AC, grid-tied.

Re: FNDC Wiring question... SOC dropping

Postby Jake33 on Thu Sep 07, 2017 5:41 pm

That makes total sense to me thank you. I never even considered the second ground wire for the charge controller. I will let you know how it's working when I get some time to head up there. Thank you
Jake33
Member
 
Posts: 5
Joined: Tue Aug 15, 2017 5:06 pm
Location: Council, ID
My RE system: 48v, 8 X L16RE-B, Mate 3, FM60, FX2548,FNDC, 6 X 150w panels


Return to FLEXnet DC

Who is online

Users browsing this forum: Bing [Bot] and 2 guests

cron