SOC suddenly jumps to 100%

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SOC suddenly jumps to 100%

Postby Kent Osterberg on Mon Feb 13, 2012 6:30 pm

The graphs below show data collected from the Mate in a customer's power system: Dual FX3048, MX60, Hub, Mate (firmware 4.2.1), and FNDC (firmware 001.000.071), 20-kW Onan, 2800 watts of PV, and a 400-amphour battery system.

The FNDC is setup with charged parameters of 57 volts, 12 amps (3%), for 4 minutes, and efficiency factor = 90%. The Battery Full data stays at zero showing that the "charged parameters" are never satisfied and that the Mate would never show the SOC in flashing bold font. The graphs clearly show that there is more that resets the FNDC to 100% than is in the manual. Outback tech support has informed me that "there is undocumented logic in the FN-DC which can cause the jump to 100% SOC."

Graph30Dec11.JPG
30 Dec 2011


Graph01Jan12.JPG
1 Jan 2012


Graph03Jan12.JPG
3 Jan 2012
Last edited by Kent Osterberg on Mon Feb 13, 2012 6:41 pm, edited 1 time in total.
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Re: SOC suddenly jumps to 100%

Postby Kent Osterberg on Mon Feb 13, 2012 6:32 pm

A couple more graphs:

Graph07Jan12.JPG
7 Jan 2012


Graph17Jan12.JPG
17 Jan 2012
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Re: SOC suddenly jumps to 100%

Postby blackswan555 on Tue Feb 14, 2012 6:55 am

The FNDC is setup with charged parameters of 57 volts, 12 amps (3%), for 4 minutes


you want to be .4 v > .8v below your absorb,
12 amps is to high, looking at 7th jan, your amps are still dropping off reasonably quickly > 8amp - you want to see this flat-line to get a base number, temp compensation will mess with it a little :roll:

Graphs,,, interesting,,,,,, :grin:

30th 1st & 7th Jan, I would say AH in > out hitting zero did the 100%
3rd Jan, Same thing happens 2 weeks later on the 17th at about the same time of day, Gardener ? pool cleaner ?

But on all of them I can not see the meeting 100% is doing anything anyway ?

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
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Re: SOC suddenly jumps to 100%

Postby SteveHiggins on Tue Feb 14, 2012 7:08 am

What's your Absorb Time set to?

If you meet

1. Absorb Time

Or

2. Charge Parameters Met (Time, Voltage and Return Amps)

Or

3. Amps Out +Amps In (With BCF%)

You will see this.
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Re: SOC suddenly jumps to 100%

Postby Kent Osterberg on Tue Feb 14, 2012 10:30 am

The FX inverters are programed for an absorption voltage of 58.4 volts for 3 hours, but the AGS overrides that and shuts the generator off at 95%.
The MX 60 absorption voltage is 58.4 volts for 3 hours. Float is set to 56.0 volts (a somewhat aggressive finish, when there is enough solar, but it shouldn't increase water consumption by any noticeable amount).

Obviously, there isn't much solar energy for the days graphed. On each day shown the generator started at 65% SOC and shut down, as programmed, at 95% SOC. The exception is that on the 1st the owner shut it down at 85% SOC. After the 1st no one is there and the only loads are the refrigerator, radiant floor circulating pumps, boiler controls, and the inverters. These are the only days that the generator ran.

On the 3rd the FX held the absorption stage for slightly less than a hour, ending with a current near 25 amps.
On the 7th the FX held the absorption stage for about an hour, ending with a current near 22 amps.
On the 17th the FX held the absorption stage for about 90 minutes, ending with a current near 17 amps.
I agree with Tim, these currents indicate the battery is still not fully charged - it is supposed to be about 95% and it is probably close to 95% SOC, maybe its at 96% SOC. Yet with virtually no additional solar charging the FNDC resets to 100% SOC. And the mechanism by which that happens is not documented -- the charged parameters are not met.

The PV system charged the batteries to 100% (charged parameters met) on the 4th, 8th, 9th, 11th, 12th, and 13th. Fortunately that happens and corrects the errors in FNDC. Had the PV system been unable to accomplish that between days that the generator ran, at what actual battery state of charge would have the generator started and stopped? Probably about 5% lower than is was supposed to.
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Re: SOC suddenly jumps to 100%

Postby Kent Osterberg on Tue Feb 14, 2012 10:52 am

Tim,

I see that I forgot to address a couple things you mentioned.

The "charged voltage" parameter for the FNDC is a little lower than you suggest it should be. That isn't, or at least shouldn't, be the cause of the observed resets to 100%. The data string from the Mate has a value that indicates when the charged parameters are met. On the days shown it remains at zero.

This is a one shunt system, Ch B and Ch C are disabled. The Ch A amphour data from the Flexnet DC is the gross amp hours in and out occurring since the FNDC last indicated 100% SOC. It doesn't include an allowance for charge correction factor, which is set to 90% for this system. So when the amphour curve reaches zero, the SOC isn't 100%. Yet it does appear that the gross amphours being zero or positive is closely related to the unexpected resets.
Last edited by Kent Osterberg on Tue Feb 14, 2012 10:58 am, edited 1 time in total.
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Re: SOC suddenly jumps to 100%

Postby SteveHiggins on Tue Feb 14, 2012 10:56 am

What's the Model # of the Inverter?
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Re: SOC suddenly jumps to 100%

Postby Kent Osterberg on Tue Feb 14, 2012 10:59 am

It is a dual FX 3048T system.
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Re: SOC suddenly jumps to 100%

Postby timmartin on Thu Feb 06, 2014 5:24 pm

SteveHiggins wrote:If you meet
1. Absorb Time
Or
2. Charge Parameters Met (Time, Voltage and Return Amps)
Or
3. Amps Out +Amps In (With BCF%)

You will see this.


In my case, my SoC jumped from 92% to 100% in a 10min window (my data logging takes data points every 10 min). The dual charge controllers were still both in Bulk. The charge parameters weren't met (or shouldn't have been) as the CCs were charging at a much higher current. Perhaps amps in == amps out, but that shouldn't matter if the params aren't met, correct?

It should be noted that my SoC jumped to 100% but my "days since full" remained at 15.7 days.

I've been tracking and trying to troubleshoot my issues over in a thread where I am hypothesizing that my MX60 is somehow causing my problems.
viewtopic.php?f=9&t=7395&start=0
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Re: SOC suddenly jumps to 100%

Postby Kent Osterberg on Thu Feb 06, 2014 10:24 pm

Did your generator run earlier in the day? If the battery voltage is temporarily raised above the charged value, the FNDC can reset prematurely later in the day. It'll often happen on marginal solar charging days. Unless you are logging data, which most folks aren't doing, it is really rare to observe. Outback knows about this defect and apparently has decided to do nothing.
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Re: SOC suddenly jumps to 100%

Postby timmartin on Mon Feb 17, 2014 4:09 pm

Kent Osterberg wrote:Did your generator run earlier in the day? If the battery voltage is temporarily raised above the charged value, the FNDC can reset prematurely later in the day. It'll often happen on marginal solar charging days. Unless you are logging data, which most folks aren't doing, it is really rare to observe. Outback knows about this defect and apparently has decided to do nothing.


I'm not running my generator at all, but my battery voltage is being pushed a bit higher. I assume it's because the the charge controllers are temp compensated... it was only about half a volt higher than the set point.

Overall, this has happened two or three times since I posted it originally. In fact, it seems to happen every day that I would actually get a real full charge. I guess it's not my MX fouling the communications... Maybe it's the FNDC causing a problem? or even the Mate3 in coordination with the FNDC? I think my system has been stopping charging early even though there's sun available to finish the job.

MonitorMate — Daily.pdf
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Re: SOC suddenly jumps to 100%

Postby Kent Osterberg on Mon Feb 17, 2014 8:30 pm

Because of the sporadic resets to 100%, it's probably a good idea to disable charge termination based on the FNDC.
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Re: SOC suddenly jumps to 100%

Postby timmartin on Tue Feb 18, 2014 5:19 pm

Kent Osterberg wrote:Because of the sporadic resets to 100%, it's probably a good idea to disable charge termination based on the FNDC.


True.

Do you think this is entirely a bug in the FNDC? I don't think there's been a firmware update to the FNDC since i got it (2+ years ago) and it seems unlikely that this is a hardware issue.

It's perplexing because I thought it was working correctly for these two years, but maybe since i wasn't data logging and graphing it maybe it had this problem all along!
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Re: SOC suddenly jumps to 100%

Postby Kent Osterberg on Tue Feb 18, 2014 6:37 pm

I think the behavior that you are seeing is a known bug in the FNDC. And as far as I know the ones shipping today have the same firmware as the original. I was told that the FNDC wasn't designed to have its firmware upgraded, so ones in the field are just stranded with the bug.
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Re: SOC suddenly jumps to 100%

Postby tallgirl on Thu Jan 01, 2015 4:44 am

Greets,

As a rule I try not to step on other professionals' toes, so I didn't give this thread a thorough going-over when it was new. That and I had a rather large sale going on at the time ...

These settings are almost certainly wrong --

The FNDC is setup with charged parameters of 57 volts, 12 amps (3%), for 4 minutes, and efficiency factor = 90%. The Battery Full data stays at zero showing that the "charged parameters" are never satisfied and that the Mate would never show the SOC in flashing bold font. The graphs clearly show that there is more that resets the FNDC to 100% than is in the manual. Outback tech support has informed me that "there is undocumented logic in the FN-DC which can cause the jump to 100% SOC."


The "57 volts" value is only appropriate for a battery bank where the absorb voltage is around 57.2 volts, which isn't even an AGM battery. It's been a while since I used AGMs, but 57 volts for end of charge is almost certainly wrong.

The "12 amps" value, which he says is 3%, is also almost certainly wrong. Three percent is horrible for flooded batteries, and completely unheard of for AGMs. Since a 57 volt value is barely appropriate even for AGMs, the combination of 3% return current and 57 volts is just plain wrong, in my opinion. Back when I was working on automatic grid control (some really slick features that predictively connect and disconnect from the grid to avoid exporting power) my return current was around 1.5%. Years of wear-and-tear later and the correct "full" charge return current is just under 2%, though I use something just over 2% so I don't spill too much power as I'm grid-tied.

With the settings given above the FNDC will periodically report "parameters met" before and during the start of Absorb. This may happen immediately after periods of very high rate of charge prior to Absorb when electrolyte density near the plates is higher than normal, or it may happen during Absorb when input current quickly drops.

The cycle efficiency is most likely set correctly. Something in the 85 to 95 percent range (higher ranges for AGM and Gel, lower ranges for FLA) is usually correct, but must be determined experimentally and adjusted on a regular basis.

The solution is to service the batteries to proper working conditions, then experimentally set the voltage and return current to the correct values. Anything else, including fiddling with cycle efficiency, is a waste of time.
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