SOC suddenly jumps to 100%

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SOC suddenly jumps to 100%

Post by Kent Osterberg » Thu Mar 13, 2014 5:56 pm

This graph is from another customer that is experiencing the FNDC bug that causes the SOC to suddenly jump to 100%. The consequences of this bug are hardly trivial. After the AGS starts the generator at 65% SOC charge on March 1st, the charging terminates prematurely when the SOC is reset to 100% at 0:14 on March 2nd. This leaves the FNDC indicating the incorrect SOC which causes subsequent generator starts to be triggered on the voltage threshold and to terminate at 95% SOC as indicated by the FNDC when the bulk charge isn't even completed.

Outback, it's well past time that this bug should be fixed!

About the graph: to make this graph I imported data obtained with RightHand Engineering's Winverter program into xcel.
Graph for 2 March 2014.JPG

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Re: SOC suddenly jumps to 100%

Post by vtmaps » Fri Mar 14, 2014 12:23 pm

Kent Osterberg wrote: Outback, it's well past time that this bug should be fixed!
Do you think anyone from Outback reads or participates in this forum? They're probably too busy removing useful information fro their manuals :sad: --vtMaps

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Re: SOC suddenly jumps to 100%

Post by timmartin » Sun Mar 23, 2014 11:35 am

Well Kent,

Here's my data from March so far. In 23 days I see 10 of which the FNDC "jumped" to 100%. Most of the time it did it rather late, only jumping from 98% to 100%, but if you look at data from the 1st and 5th it jumped from 96% and 94% respectively.
Screen Shot 2014-03-23 at 11.31.27 AM.png
The 10 days in the last month which skipped at least one percentage point of SoC: http://finleyridge.com/powerlogs/MonitorMate-March.pdf

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Re: SOC suddenly jumps to 100%

Post by Kent Osterberg » Mon Mar 24, 2014 10:10 pm

From your graphs it looks like you have the FNDC connected to three shunts. If you can look at the amphour data, I think you'll see what causes the reset. You'll probably conclude that given a few hours with the source code, this FNDC bug could be fixed.

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Re: SOC suddenly jumps to 100%

Post by timmartin » Wed Mar 26, 2014 9:45 am

Kent Osterberg wrote:From your graphs it looks like you have the FNDC connected to three shunts. If you can look at the amphour data, I think you'll see what causes the reset. You'll probably conclude that given a few hours with the source code, this FNDC bug could be fixed.
Yes, I am using all three. I've contacted support (via email) and furnished them with all the same information. I am awaiting a response with baited breath.

As for trying to dig into this and see what specific part of my situation causes this, you're saying that charting the Ah in and out, per shunt and/or combined would help determine the jump? Perhaps it's entirely unrelated but I also keep lowering my charge factor and it doesn't seem to be changing the amount of time the system sits at 100% before charge params are met. I was noticing it was getting to 100% about an hour before the return amps was being reached, so I figured I should lower my charge factor to get it down to the point where it gets to 100% just before my charge params are met. I keep lowering it and I'm not seeing a correlation with this offset of time.

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Re: SOC suddenly jumps to 100%

Post by timmartin » Wed Mar 26, 2014 12:30 pm

Support said this:
This is our solution to that question.

FNDC Logic (SOC jumps to 100%) Solution Details

The FLEXnet DC has undocumented logic which can cause a jump to 100% SOC.

Net amp hours> 0 AND Battery volts< ( Absorb setpoint - 0.5 ) AND
Average net amps (to the battery)> 0

Adjusting charge factor is one way to ensure a smooth transition to 100%.

It decides parameters meet based on the parameters that are set. Yours may require some adjustment as discussed in the document.
This doesn't really help me though. I've been adjusting the charge factor and it's not getting better.

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Re: SOC suddenly jumps to 100%

Post by vtmaps » Wed Mar 26, 2014 12:54 pm

timmartin wrote:Support said this:
This is our solution to that question.

FNDC Logic (SOC jumps to 100%) Solution Details

The FLEXnet DC has undocumented logic which can cause a jump to 100% SOC.

Net amp hours> 0 AND Battery volts< ( Absorb setpoint - 0.5 ) AND
Average net amps (to the battery)> 0
volts are below absorb and the current > 0 ..... that sounds like bulk or float... and then using net amphours to tell the difference between the two. Something in this logic escapes me.

In the winter my Trimetric monitor often jumps to 100% from somewhere in the high 90's. Only in the winter. My absorb voltage is set to 29.6 volts. The trimetric resets to 100% when the voltage is 29.6 (or higher) and the amps is 4 (or lower) for a minute.

The reason for the reset is that my batteries are cold, and with temp compensation my FM60 will absorb at 30.2 (or a bit higher). If I am near a full charge (amps are still a bit higher than 4), and a cloud passes by, the voltage and current may drop a bit and trigger the reset (the trimetric doesn't know that the temp compensated voltage is really 30.2 volts).

I don't know much about the flexnet DC.... could the reason for the reset be similar to my trimetric situation?

--vtMaps

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Re: SOC suddenly jumps to 100%

Post by Kent Osterberg » Wed Mar 26, 2014 1:21 pm

The FLEXnet DC has undocumented logic which can cause a jump to 100% SOC.
This is nothing but fancy speak for "design flaw". As shown above, it causes other useful features such as turning the generator off at 95% SOC to work poorly too.

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Re: SOC suddenly jumps to 100%

Post by tallgirl » Thu Mar 27, 2014 6:55 am

Kent Osterberg wrote:
The FLEXnet DC has undocumented logic which can cause a jump to 100% SOC.
This is nothing but fancy speak for "design flaw". As shown above, it causes other useful features such as turning the generator off at 95% SOC to work poorly too.
Not so much "design flaw" as "unintended consequences".

I've had this problem myself before and my fuzzy memory is that incorrect "charge factor", sulfated batteries, and some other corner cases, make it worse. I believe it also jumps when "Parameters Met" happens, and I've seen a LOT of systems where those settings are wrong.
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Re: SOC suddenly jumps to 100%

Post by timmartin » Thu Mar 27, 2014 8:10 am

tallgirl wrote:I've had this problem myself before and my fuzzy memory is that incorrect "charge factor", sulfated batteries, and some other corner cases, make it worse. I believe it also jumps when "Parameters Met" happens, and I've seen a LOT of systems where those settings are wrong.
I'd expect it to jump to 100% if params are met. And that would occur if you had your charge factor set too low (right?) because the FNDC would be discounting the incoming Ah too heavily, so the system wouldn't read a 100% despite the voltage being held at absorb and the return amps dropping to the right value.

So either I still have my charge factor too high (to which I'm skeptical since i'm down to 86% and the problem isn't getting any better) or something else is going on.

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Re: SOC suddenly jumps to 100%

Post by tallgirl » Fri Mar 28, 2014 4:12 am

Tim,

There are some common-ish things that happen with batteries, and FNDC setups, that can fool the poor thing into believing the charge parameters were met, or confusing it about them not being met. Without knowing the rest of the things about the system, "It jumped, therefore it is broken" is simply wrong.

I will tell you that if a system is being chronically under-charged, the FNDC is more than happy to help it become more chronically under-charged. The reason is that most people can spot over-charging, or else their system requires running a generator to overcharge the batteries on a regular basis. Under-charging is so much easier, and as a battery bank is under-charged, and the batteries slowly get sulfated, the FNDC just can't tell.

The things are great devices, but they aren't a substitute for taking hydrometer readings and knowing how healthy your batteries actually are.
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Re: SOC suddenly jumps to 100%

Post by timmartin » Fri Mar 28, 2014 3:05 pm

Perhaps it's not broken. But it's not reporting information correctly, and everyone (outback tech support) seems to say that it's something I'm doing. But NOBODY can tell me what the problem really is. I'm happy to do any tests, provide any data, try anything at all. But Outback just said "if you lie to it then it will lie to you". Intimating that I've done something wrong, and using the word "lie", really isn't productive. I'm well aware that I could be the cause, and that I certainly am part of the solution.

So I'm looking at this undocumented logic, and i'm looking at the charts I posted. One of the 3 evaluations was that it be *less than* the absorb set point. But in almost every single case of this in my own data, the battery voltage is well above the absorb set point. This happens during BULK charging on sunny days... days it would have legitimately gotten to 100% in just a little bit more time. Now my data is at 5 min intervals, so perhaps something happens in that 5 mins that I'm not aware of... but it'd be great if I had a clue of what I was looking for.

And why does my lowering of the Charge Factor not seem to be changing anything?

So what do I *actually* do at this point? My system is not being chronically undercharged. It may be sulfated, I really don't know. They tend to bubble and outgas regularly, and I EQ every 2 or 3 months. I just want to get it to stop jumping to 100% when I know for a fact the batteries aren't fully charged yet.

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Re: SOC suddenly jumps to 100%

Post by tallgirl » Fri Mar 28, 2014 5:51 pm

Tim,

"Parameters Met" requires a voltage ABOVE the target voltage and a current BELOW the target current.

One of the most common mistakes I see is setting the voltage more than a "click" (0.1v for 12 volt, 0.2v for 24 volt, 0.4v for 48 volt) below the actual voltage, and the current more than 0.5 amps above the "ending" current.

What happens when the parameters are configured incorrectly in that manner is the parameters will be "met" before the batteries reach "Absorb". Instead of reaching absorb on high current, a situation where the current is barely enough to even =reach= absorb will result in the voltage and current values being satisfied. That's how it starts, and from there, it progresses. Once the batteries are slightly under-charged, sulfation begins. Sulfation causes the "return current" to drop, which is the same behavior as being fully charged for properly maintained batteries. The more the batteries are sulfated, the more the "return current" declines, the easier the parameters are to meet, the more undercharged the batteries become.

And this is where the "jump" happens, because sulfation results in premature "Parameters Met".

There is another scenario -- too low of a "Charge Factor" value. When the "charge factor" value is set too LOW, the batteries actually =do= reach the proper ending values, and the FNDC results the SoC back to 100% to reflect that. Then the batteries are discharged, and while they are being recharged, too few amp-hours are credited back, the SoC rises too slowly, the batteries complete their charge well before 100%, and the "jump" happens.

I have a lot of respect for Kent, because he is one of the more qualified solar professionals I've known over the years, but he's wrong in this regard. There =are= bugs in the FNDC, but this issue has multiple causes, some of which indicate configuration or battery maintenance issues.

Whenever a system has "The Jump Bug" the first step is figuring out the actual state of the batteries, then carefully configuring the settings. Then, and only then, should one blame the FNDC. As an aside, I've never seen a properly configured system, with proper and regular battery maintenance, have this bug.
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Re: SOC suddenly jumps to 100%

Post by vtmaps » Fri Mar 28, 2014 6:50 pm

for those interested, this problem has been discussed here on several occasions:

http://www.outbackpower.com/forum/viewt ... =28&t=6046
http://www.outbackpower.com/forum/viewt ... =28&t=5787

From topic 5787:
A year ago Steve Higgins promised that Outback would publish documentation about the situation that causes the Flexnet DC to prematurely reset to 100%. It still hasn't happened; I suspect it won't either.

Reducing the return amps will not help; none of the user adjustments will prevent this from happening. If the voltage is raised to the "charged" value at any time prior in the day, and the unadjusted (the charge efficiency hasn't been applied) amphours reaches zero or higher, then the FNDC will reset when the charge current drops down to zero. Obviously this is a different criteria than simultaneous "charged" voltage and return amps that is published on the spec sheet and in the manual. The events that I've seen make it happen are when the generator runs in the early A.M. raising the voltage to the charged value, then later in the day with cloudy conditions the solar system causes a reset when the battery current goes negative briefly when a cloud passes.
--vtMaps

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Re: SOC suddenly jumps to 100%

Post by Kent Osterberg » Sat Mar 29, 2014 6:57 pm

I believe Steve Higgins is no longer with Outback, that unfortunate because he knew the product line really well. Back when I originally put a post up on this subject, I had a telephone conversation with him about the FNDC and the data I had collected was sent to Outback. What my data showed is that In some circumstances, if the amphours to the battery without adjustment for the charge efficiency factor reaches zero, the FNDC will reset to 100% even though the charged parameters are not met. Steve described the "undocumented feature" that causes the reset similar to what was posted above. My point in bringing this topic up again was to show that the "undocumented feature" has negative consequences in regards to AGS operation. That's too bad because the biggest advantage the FNDC has over less expensive battery monitors is the ability to use SOC for AGS operation. If that can't be relied on, it probably not worth owning a FNDC.

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Re: SOC suddenly jumps to 100%

Post by timmartin » Sat Mar 29, 2014 10:05 pm

And this is where the "jump" happens, because sulfation results in premature "Parameters Met".
Tallgirl, I think most of us understand (and agree) that the device should jump to 100% if the parameters are met. That's the point of the parameters in fact... But Kent and I are talking about a case that doesn't appear to have anything to do with the charge parameters.
Window.png
Looking at the last few times it happened, it does seem to occur right when (or close to) the time that temp compensated absorb voltage setpoint is reached.
Pasted_Image_3_29_14__9_57_PM.png
So we know it's not because of charge params. The other earlier theory had to do with reaching the correct voltage earlier in the day, but as you can see in my graph, that's not true in my case either.

I'm going to create some new graphs, probably a three-series graph that has the net aH and charge factor compensated net aH for the batteries. I'll plot that along with the voltage and/or SOC and see what shows up. If anything.

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Re: SOC suddenly jumps to 100%

Post by timmartin » Sat Mar 29, 2014 10:36 pm

Welp, it is when Net Ah hits zero... but compensated is nowhere near zero.

*sigh* more evidence but nothing that helps.
Screen_Shot_2014-03-29_at_10_33_50_PM.png

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Re: SOC suddenly jumps to 100%

Post by tallgirl » Sun Mar 30, 2014 10:36 am

timmartin wrote:Welp, it is when Net Ah hits zero... but compensated is nowhere near zero.

*sigh* more evidence but nothing that helps.
Screen_Shot_2014-03-29_at_10_33_50_PM.png
What were the volts and amps when that happened? What are the "parameters met" settings?
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Re: SOC suddenly jumps to 100%

Post by timmartin » Mon Mar 31, 2014 10:36 am

tallgirl wrote:What were the volts and amps when that happened? What are the "parameters met" settings?
Charge Parameters: 58.8 V, 12.5 A, 10 minutes. And here's a snapshot of the data before and after the jump in SOC:

1:20pm - 92% SOC
Batt Voltage: 59.4 V
Charging Current: 40.6 A
Net Power (Batt): 2412 W
Net Accumulated Ah: -1 Ah
Charge Factor Corrected Net Ah: -82 Ah

1:25pm - 100% SOC
Battery Voltage: 59.4 V
Charging Current: 39.8 A
Net Power (Batt): 2364 W
Net Accumulated Ah: 0 Ah
Charge Factor Corrected Net Ah: 1 Ah

You can inspect this data live: http://finleyridge.com/power/historical ... 2014-03-28

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Re: SOC suddenly jumps to 100%

Post by timmartin » Wed Apr 02, 2014 9:28 am

Same Charge Parameters: 58.8 V, 12.5 A, 10 minutes. And here's yesterday's 15% jump!

1:35pm - 85% SOC
Batt Voltage: 55.1 V
Charging Current: 18.1 A
Net Power (Batt): 997 W
Net Accumulated Ah: -1 Ah
Charge Factor Corrected Net Ah: -158 Ah

1:40pm - 100% SOC
Battery Voltage: 55.2 V
Charging Current: 16.9 A
Net Power (Batt): 933 W
Net Accumulated Ah: 0 Ah
Charge Factor Corrected Net Ah: 0 Ah


So I was told "Net amp hours > 0 AND Battery volts< ( Absorb setpoint - 0.5 ) AND Average net amps (to the battery) > 0"

Net Ah > 0, TRUE! I'm assuming it's >= or internally it has greater precision than the data it displays.
Bat V < (Absorb -0.5), TRUE! It was a gray and partly cloudy day, so the voltage rarely went up to the set point.
Avg Net A > 0, TRUE? I wonder what they mean by average? Average over what period of time?

So unlike my previous post, this situation possibly matches the "undocumented logic". However, I honestly don't see how this logic makes any sense. Why would the system consider the battery to be charged when the uncorrected battery Ah is zero (why not the corrected value??) the Battery is BELOW the absorb set point (why not above?) and the Avg incoming power is positive. This would appear to be a situation where the battery is not yet charged, but is in the process of getting charged... I swear he must have typed one of the evaluations backwards...

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Re: SOC suddenly jumps to 100%

Post by timmartin » Wed Apr 02, 2014 9:33 am

In summary I should say that in my testing it appears as though the FNDC is going to reset to 100% when the net Ah reaches zero, pretty much no matter what I do. So I could set the charge factor back to a realistic value but it won't change when the FNDC gets to 100%, it will simply make the graph line have a steep yet consistent slope to approach the 100% instead of a sudden jump at the end.

So it appears as I do NOT have the ability to get my system to "Get to 100%" later in the day, when it would be more technically correct. No matter what I do I'm going to be 5% to 15% off in my readings at all times. If the system reaches it's reported 100% but then doesn't stay there for the necessary hour or more to meet the charge parameters, then I can consider all readings after that to be considerably inaccurate. The higher the "days since full charge" goes, the worse the accuracy. Mind you, I always knew that to be true, but I had no idea it was to inaccurate to such a large degree.

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Re: SOC suddenly jumps to 100%

Post by Kent Osterberg » Wed Apr 02, 2014 6:30 pm

Tim,

The known but not publicly documented bug (Outback still hasn't made any description of the "undocumented logic" public) doesn't happen every charge cycle. In some manner, it depends on some other conditions happening too. But it is pretty much out of the users' control. Since the size of the jump is bigger if the charge efficiency setting is lower, you could set the charge efficiency really high (which is appropriate for many AGM battery installations anyway), but that simply substitutes one problem for another problem that actually may be, probably is, worse.

For anyone using the SOC stop feature for the AGS function, the bug will cause the results shown at the origin of this topic. So the only lesson I've got from this is that the AGS stop SOC% feature will cause erratic generation operation with short incomplete charge cycles being the primary symptom. So if the AGS stop SOC% feature is used, the "charge until full feature" better be used too, and set to a reasonably low value - say every seven days - or less.

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Re: SOC suddenly jumps to 100%

Post by HawaiianDrummer » Thu Apr 03, 2014 3:46 am

Aloha, Thanks Kent for your pursuit to help us who are using the FLEXnet DC, I follow all these posts from everyone and concur with your reasoning, as my FLEXnet DC also jumps to 100% SOC all the time and I have run the full gamut on settings also. Presently I am using the lowest charge factor that the FLEXnet DC allows 65% (I have tried 90%, 85%, 77% & 72%) and I set 2% of my 1,110 AH 24 ea. 2V Trojan batteries as 22A for the end of charge return Amps ( I have also used 0A), Charge Parameters Time met 10 Mins. (I have tried 2 mins., 30 mins., 1 hr.) the battery End of charge voltage is set .4 V below my 48 V system Absorb V always. The one factor that is working for my set up is that on full sunny days the charging STILL CONTINUES when the FLEXnet DC shows FULL, so I am happy for that, but I don't know what setting is allowing that from which component. I had originally set the charge until full for every 30 days....(I don't remember where that is set) On all our cloudy mornings here in Ninole, Hawaii of the Big Island my generator runs from 2 to 3 or 4 hrs starting at 6:00 A.M. to INSURE my expensive battery bank is kept above 47.6 VDC I don't often check to see what initiates the gen so it could be SOC or Voltage start. I'm still lead to think that the FX and FM settings can also take control over the FLEXnet DC settings, with a mathematical IF/THAN/OR/AND programming deficiency, hindered by TOO many similar related set points that can take control from each other. Maybe a better Mate/Hub program that can better "dictate" priority...just my thoughts. David
Last edited by HawaiianDrummer on Thu Apr 03, 2014 2:07 pm, edited 1 time in total.

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Re: SOC suddenly jumps to 100%

Post by Kent Osterberg » Thu Apr 03, 2014 10:40 am

David,

I think you mean that the FNDC jumps to 100% SOC. I don't know of anything jumpy about the parameters met feature. Of course, when parameters are met the SOC should reset or jump to 100%. But all of the other jumps to 100% are inappropriate.

I think that the "charge until full" number of days is an advanced setting in the Mate. It allows the FNDC to put all the charging devices in float mode at the same time when the charged parameters are met. I don't know of any problem with this feature, but I haven't used it because I don't think it is important to have all of the charging devices coordinated.
Last edited by Kent Osterberg on Thu Apr 03, 2014 5:11 pm, edited 1 time in total.

HawaiianDrummer
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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, 6 SimpliPhi 67 AH 48 batteries for 402 AH Battery
bank, Flexnet DC and Optics RE
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Re: SOC suddenly jumps to 100%

Post by HawaiianDrummer » Thu Apr 03, 2014 2:27 pm

Aloha, Thanks Kent, I edited my post to jumping to 100% SOC. and thanks for the reference on where to set floating all components to full charge in the advance Mate. We need ALL "Time Met" settings specific to letting ALL the charging complete, without allowing the FLEXnet DC to display 100% SOC when ANY of the set points are reached, by any component. BUT rather when ALL settings are reached. Still hoping a Mate upgrade could be designed to accomplish this in the very near future from OutBack Power Technologies. Thanks, David

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