Grid hybrid FNDC settings

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Grid hybrid FNDC settings

Postby Sida on Wed Oct 08, 2014 4:02 am

Hi all,

I am trying to configure the FNDC to correctly manage the battery charging of my system.

System is fairly basic at the moment, consisting of: GVFX3024e grid tie for charging 2x 210ah rolls AGM batteries (24v). Connected in the system is a MATE, hub and FNDC and RTS

My issue is that I cannot seem to ever get to "charge parameters met" without manually setting the MATE to start a bulk charge. Most of what I have read is for off grid systems or systems that recharge via some form of renewable source, which currently mine does not. My thinking is that my batteries are not been depleted enough to initiate the absorb charge stage and is skipping staight to float, as when I watch the battery voltage drop to the refloat threshold it just tops them back up to the float charge settings

Settings are as follow,
Absorb 29.8v 1.5hrs
Float 27.6v 2hrs
Re-float 25.6v
Batteries are fitted with RTS

FNDC Return amps 4.4 for 1min
BCF 94%
End of charge 0.2v.
SOC is either 99 or 100%. It does not drop below this as it is just recharged by the grid. I have ran it down a few times to calibrate the FNDC and will do once or twice a month for the sake of maintaining the batteries.

Thanks
Sida
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My RE system: Rolls AGM 210ah 24v battery bank, outback gvfx3024e, outback mate/FNDC Lister lt1 & markon 5 kwa gent.

Re: Grid hybrid FNDC settings

Postby klundquist on Wed Oct 08, 2014 8:42 am

I would be surprised if 1.5 hours of Absorb are enough to meet your end amps setting. I have a VFX2812 with a 12 volt 200RE battery and I had to Absorb for over 6 hours to meet charge parameters.

Is the 0.2v end of charge voltage a typo? I would expect something around 29.6. Also if the batteries are new I would aim closer to 1% End Amps (2.5 or 3 amps). This will make it more difficult to meet charge parameters but it is likely this is what your batteries want.

The "skipping straight to float" behavior you notice is not really skipping. The inverter has a "re-float" voltage set point. When the batteries hit re float and the charger is enabled the inverter will run a float charge on the batteries.

The 24V G model FX's typically have a non programmable rebulk voltage around 24.4 VDC. If you want the system to do a bulk charge instead you will need to set your refloat voltage below 24.4. As another option you could just manually force bulk from the Mate when necessary (press AC IN button 4 times then BULK>START).

For most efficient battery use I suggest you make sure SELL is disabled (ADV>FX>PG2>PG3>PG4>SELL>DOWN>DOWN) Grid Tie Authority should say "No Sell".

-Kurt
Kurt Lundquist
Alpha Energy Systems Engineer
http://www.alpha.com/solar
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My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank

Re: Grid hybrid FNDC settings

Postby oldbrowhnat on Thu Dec 04, 2014 12:32 pm

May I tag along on this? I am (very belatedly) getting around to doing some proper routine (plus equalization cycle) on my system and have come across the "refloat" parameters (voltage & time) on the FX, but I have no info on how to set this, although I have the recommended bulk, absorption, float and EQ parameters.

:) Stuart
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My RE system: Outback VFX 3524, Mate 2
8 x GC-220.

Re: Grid hybrid FNDC settings

Postby HawaiianDrummer on Fri Dec 05, 2014 12:28 am

Aloha, My thinking is that your being "on grid" the battery charging is always being kept up, so you have no worries and should be thankful. David
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My RE system: 1-FM60's, 2-FM80's 2- FX3048's, Mate3, Hub 10, 12 US 64 w panels, 12 Kyocera
175 W panels, 21 Kyocera 225 W panels, 24 Trojan 2V 1,110 AH 48 V Battery
bank, Flex Net DC and Optics RE

Re: Grid hybrid FNDC settings

Postby oldbrowhnat on Fri Dec 05, 2014 5:02 am

HawaiianDrummer wrote:Aloha, My thinking is that your being "on grid" the battery charging is always being kept up, so you have no worries and should be thankful. David

Well, I am thankful that I've rarely had to rely on backup power, and somewhat less so in the last few years as BC Hydro has been more aggressive about keeping the lines free of trees. And at least we don't have to worry about encroaching lava! The supplier of the system does recommend equalizing the batteries 3-4 times a year, though. We are apparently overdue for an earthquake here, however, so I figure I'd better start taking the system seriously. I'm looking into a small diesel generator as well.

I got a reply from the supplier yesterday and they suggested using the same voltage and time as for FLOAT, so I'm going to go with that for now.

Mahalo :)
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My RE system: Outback VFX 3524, Mate 2
8 x GC-220.

Re: Grid hybrid FNDC settings

Postby HawaiianDrummer on Sat Dec 06, 2014 1:53 am

Aloha, I agree on using those float settings since the battery bank is at a full charge most of the time. Keep us posted. David
HawaiianDrummer
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Posts: 323
Joined: Thu Apr 02, 2009 1:42 am
Location: Ninole, Hawaii
My RE system: 1-FM60's, 2-FM80's 2- FX3048's, Mate3, Hub 10, 12 US 64 w panels, 12 Kyocera
175 W panels, 21 Kyocera 225 W panels, 24 Trojan 2V 1,110 AH 48 V Battery
bank, Flex Net DC and Optics RE


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