Hi guys, me again - sorry, and thanks.
I've been trying to get to the bottom of my widely divergent SOC calculations from my WhizBang Jr equipped Classic 250 (rev 4) and my MNSHUNT equipped SMA Sunny Island SI6048.
Looking at historical readings from the WhizBang Jr, and the SMA the numbers are all over the place. This morning I was standing in front of the console when I noticed something weird, the Si6048 was showing a 60+ A draw from the battery, but the WhizBang Jr showed around 8 A, about what I expect early AM before everything wakes up. This continued long enough for the Si6058 to adjust it's SOC down from 70% SOC (WBjr said 89%) to 20% (it goes to 20 in an attempt to recalibrate SOC after confusing data) SOC - WBjr still says 89%.
So this causes me to look at everything I can find as to a record of shunt readings. The biggest thing that jumps out at me is the Maximum reading from the SI6048 - 198A out 177A in - According to my MyMidnite WhizBang Jr data I've never come close to either. The charge rate is set limit at 70A, and my array is only 6kw with the two never at the same time. IF I turned on every piece of equipment we have all at the same time I'd never hit 198A, we rarely exceed 50A out and even then not for long.
I guess what I'm trying to ask is, could my shunt be bad? Is there a way to test it?
I'm going to stick my head out on this one, so here goes,
Shunts don't go bad!
Unless one took a lightening strike, there's nothing to go bad.
Basically, a very, very, very low Ω resistor that the whizbang reads the resutling voltage drop across the shunt. If I remember, the shunt with the whizbang is 500 A at 50mV. Which means when 500 A of current is flowing, there will be 50 mV produced across the shunt.
To test one, you can use a good VOM, set it for 1x Ohms range.
Now a good meter will read it's own meter leads resistance, so you'll see .3 Ω or something close when the tips are connected to each other. Take a lead from the meter at one end of the shunt, and the other at the opposite end. The reading should go up a tiny bit, that's the resistance of the shunt. Most digital meters will have an issue trying to resolve such a low value.
To really get down and dirty, you'll need to use a 4 wire resistance measuring device of which I can't recall the proper name.
Bottom line is if you have continuity between the ends, the shunt is good.
Mike, wb8vge
Thank you, since it does not agree with the WhizBang Jr, how do you test the WBjr?
And yes I have a trouble ticket at SMA in the chance that the SI6048 itself might be the problem.
Where exactly are you reading the Whizbang from ?
If you are reading the system amps then it has already compensated for any loads and is only showing exactly what is going into the batteries.
So if your Classic was putting out 60 amps but the loads like inverter was taking 55 amps - the system amps is only going to show 5 amps which is what is going into the battery .
One way to test is to get a DC clamp on amp meter and put it on the wire that has the shunt and compare it to the other readings. Depending on the clamp on meter it might not be exactly as accurate as the whizbang but it would be close enough to tell you it is working correctly.
Larry
In addition to what Mike and Larry mentioned, several things:
Do the SIs use the same MNShunt, as the WbJr?
Really seems that the Si SOC readings would be most suspect, compared to the WbJr.
Yes, it is difficult for the average person to measure the voltage output of the Shunt, or its Resistance. 100A flowing either direction, yields only 5 mV. Even a 4.5 digit mulitmeter has too little resolution, and, usually too many counts of uncertainty, to measure this accurately. And, most of us do not hate 5+ digit DMMs, MicroVoltmeters, or MilliOhmmeters, which could measure either the shunt voltage, or resistance. (current flowing through the shunt would affect resistance readings).
Would suggest two things:
1. On an early morning after a full charge on the previous day, compare the Net Ah, with the SOC, either on the Classic MNGP, or using the LocalApp. Is the WbJr SOC vs Net Ah believable? Is the Si's SOC believable?
2. AND, SOC readings from any battery monitoring device are just approximations. Fairly often, these are rough approximations. Fooded Lead Acid(FLA) batteries seem to be one of the most difficult battery types for these monitors to read, due to Peukert effects on discharge, (and probably for charge, as well, difficulty in guessing battery efficiencies, temperature effects, and many other variables that we cannot know, or measure very accurately.
For FLA batteries that are cycled daily, would just look at the Net Ah in the AM, to see close to the DOD of the battery, overnight, and if the battery discharge and charge are fairly repeatable, day-to-day, you can come up with settings for the Wb, that could give general ideas of SOCs throughout the daily usage.
MyMidnite2, the free MidNite site that records snapshots of many Classic CC operating parameters, battery voltage, temps, etc, will help you get a very accurate graphic display of this date, recorded at about 10 minute intervals 24/7/365.
Have never seen a WbJr report erroneous data. We did have one very early WbJr, that stopped working after one month, or so. MN replaced it very quickly, and all of them here, have worked perfectly for more than 5 years (forget when the Wb was introduced). But, from what other company, could you get the WbJr functions, at such a LOW cost?? Amazin', to me ... Thanks NidNite !!
IMO, Vic
The WBjr is attached to the MNSHUNT.
They should both show the same thing - they both only measure what goes into or out of the battery. I can read this number directly from the SI - they do agree when I calibrate the shunt at zero, but a most loads the numbers appear to be off by about .4-.8 Amps on most of the small loads. When the generator is running the WBjr and the SI are spot on, but appear to differ greatly when the Classics supply solar energy to the battery. The SI is aware of the readings from the Classics, but the absolute shunt values do not jive with the WBjr. The shunt is between the loads/classics/SI and the battery - the shunt readings couldn't possibly compensate for what the inverter is doing, now can I access that, yes... but that isn't what is going on here.
I monitor them with the Local Ap, the Android app (not at the same time as the local app) and with MyMidNite. As far as I know the charge the Classics report to the SI via the MODBUS/Canbus adaptor are NOT from the WBjr, right? They couldn't be with only one Classic being able to read the WBjr and that data not being shared between them.
And I really wouldn't give a flip about the SI's SOC readings except when it drops to 20% to recalibrate SOC it starts up all the battery protection stuff, and cranks the generator. It's trying to literally fry the battery that it believes is 20% when it is almost fully charged.
Last night for example, the battery was fully charged - we used 168Ah. The WBjr said our SOC was 100% before and 89% after - the SI said 90% before and 70% after then suddenly dropped to 20% and cranked the generator. Of course it see's it's trying to push 70A into a pretty full battery so that starts it's own cascading failure events. I just need to make sure it isn't the WBjr, or the MNSHUNT before I demand a replacement SI6048 from SMA.
Quote from: Trukinbear on October 16, 2020, 05:56:40 PM
The WBjr is attached to the MNSHUNT.
They should both show the same thing - they both only measure what goes into or out of the battery. I can read this number directly from the SI - they do agree when I calibrate the shunt at zero, but a most loads the numbers appear to be off by about .4-.8 Amps on most of the small loads. When the generator is running the WBjr and the SI are spot on, but appear to differ greatly when the Classics supply solar energy to the battery. The SI is aware of the readings from the Classics, but the absolute shunt values do not jive with the WBjr. The shunt is between the loads/classics/SI and the battery - the shunt readings couldn't possibly compensate for what the inverter is doing, now can I access that, yes... but that isn't what is going on here.
I monitor them with the Local Ap, the Android app (not at the same time as the local app) and with MyMidNite. As far as I know the charge the Classics report to the SI via the MODBUS/Canbus adaptor are NOT from the WBjr, right? They couldn't be with only one Classic being able to read the WBjr and that data not being shared between them.
So, both the Wb AND the Sis attach to the MNShunt?, or, only the Wb is attached to the shunt, and the Classic/s report charge/discharge currents to the Si, via the Commbox?
And, the MNShunt is attached to only one Classic, via the WbJr, BUT, it sees all of the charge/discharge currents (from all charge sources, and all loads, when correctly installed), as the shunt is in the negative battery lead, where all currents appear, and can be measured.
Realize, that I know nothing of Si inverter/chargers, at all.
Possibly, a stand-alone Generator Start Module (GSM)?
Vic
Quote from: Trukinbear on October 16, 2020, 06:04:25 PM
Last night for example, the battery was fully charged - we used 168Ah. The WBjr said our SOC was 100% before and 89% after - the SI said 90% before and 70% after then suddenly dropped to 20% and cranked the generator. Of course it see's it's trying to push 70A into a pretty full battery so that starts it's own cascading failure events. I just need to make sure it isn't the WBjr, or the MNSHUNT before I demand a replacement SI6048 from SMA.
Keep in mind that the Midnite SOC is a calculated amount where the Whizbang amp reading is actual.
The SOC is determined by efficiency setting and temperature of batteries .
I have no idea how the SMA does it's SOC calculations.
Larry
Quote from: Trukinbear on October 16, 2020, 06:04:25 PM
Last night for example, the battery was fully charged - we used 168Ah. The WBjr said our SOC was 100% before and 89% after - the SI said 90% before and 70% after then suddenly dropped to 20% and cranked the generator ...
But, looking at the Wb data or Net Ah, (and your knowledge of what were the actual total demands on the battery), you could probably infer weather the Si, or the Wb are incorrect.
For the battery to actually go from 70% SOC, to 20%, what load would be required in that time interval for the Si-reported 20% to be accurate?
Also wonder if there is a firmware update avail for the Sis that might have addressed this situation.
IMO, Vic
To actually go from 70% to 20% would have required a discharge of 493Ah in a couple of minutes. I believe the WBjr/Classic to be correct, but the SI has control of everything even the Classics.
Here's a bit of FYI
I an old analog guy, and I like to watch analog meters more than a digital display.
So i connected a analog meter to the same sense wires on the Whizbang jr so I could see the current flow on a analog meter. Apparently the load from the meter caused issues with the Whizbang, so I ended up placing a 100 A 75 mV shunt in the high side of the battery lead to the inverter.
Once the meter was removed from the Whizbang's shunt, everyone was happy.
I did add a 200mA fuse in the shunt's sense wires that fed the analog meter, since I was measuring current in the high side.
There was an old dead guy named Kirchoff that said current in and current out of a node had to be the same, so a shunt in the high side will read the same as one in the negative lead like the Whizbang.
It's possible the other equipment doesn't like the shunt the Whizbang is married to. I'd add another shunt to the battery neg lead just for the external equipment and see what happens.
Mike, wb8vge
Quote from: Trukinbear on October 16, 2020, 06:04:25 PM
Last night for example, the battery was fully charged - we used 168Ah. The WBjr said our SOC was 100% before and 89% after - the SI said 90% before and 70% after then suddenly dropped to 20% and cranked the generator. Of course it see's it's trying to push 70A into a pretty full battery so that starts it's own cascading failure events. I just need to make sure it isn't the WBjr, or the MNSHUNT before I demand a replacement SI6048 from SMA.
OK, so trying to poke around in the fairly obvious, and suggesting you try things that you must have already tried;
SO, the Si system seems to not do SOC calcs that well, and therefore, SOC-driven Genstart does not seem to work well, but you have an Atkinson GenStart Mini, which you must have tried. Obviously, this module has preset voltages for Start and Stop. How did/does that work with the Si inverters?
Voltage-driven Genstart has been around for ages, and can work fairly well, depending ...
Does it create other issues, 'cause the Si s "know" that they are in exclusive, overriding CONTROL?
Just wondering, Vic
Oh yeah, it'll shut off and have us in the dark if the GSCM mini-i cranks the generator without a signal from the SI. I can't manually crank the generator either other than commanding the SI to send an order to the GSCM mini-i. I'm pretty sure this is an SMA issue, I just wanted to make sure nobody had ever had a shunt fail other than totally fail before I proceeded. It looks like they are going to send me another unit and I don't relish breaking my system down and hefting a 143# inverter down and back up on the wall. When the SI drops the SOC to 20% to recalibrate that triggers all the battery protection schemes - the SMA will not let me draw any more juice out of the battery than it thinks is OK. Sometimes that is a damn near fully charged battery it won't let me use...
Ok, Thanks, just was curious.
The old Xantrex SW+ 5548s here weigh about the same -- 143-145Lbs in the box, and about 138 Lbs, or so without the packing. Could not come close to hefting them onto the wall, without help, and that was 15 years ago, at that.
Shipping is a killer these days.
Good luck, Vic
Quote from: qrper on October 17, 2020, 10:09:19 AM
Here's a bit of FYI
I an old analog guy, and I like to watch analog meters more than a digital display.
So i connected a analog meter to the same sense wires on the Whizbang jr so I could see the current flow on a analog meter. Apparently the load from the meter caused issues with the Whizbang, so I ended up placing a 100 A 75 mV shunt in the high side of the battery lead to the inverter.
Once the meter was removed from the Whizbang's shunt, everyone was happy.
I did add a 200mA fuse in the shunt's sense wires that fed the analog meter, since I was measuring current in the high side.
There was an old dead guy named Kirchoff that said current in and current out of a node had to be the same, so a shunt in the high side will read the same as one in the negative lead like the Whizbang.
It's possible the other equipment doesn't like the shunt the Whizbang is married to. I'd add another shunt to the battery neg lead just for the external equipment and see what happens.
Mike, wb8vge
That is surprising that some analog meter would make a difference at all. The resistance of a 500A 50mV shunt is 100 micro-Ohms. I doubt that your meter would be loading anything down unless you put it into current mode. THAT would be low resistance. It would have to apply some amount of load OR maybe some voltage to affect the shunt reading I would think.
What kind of meter was it ? Was it internal battery powered ? If externally powered, I might understand some kind of connection from one of the meter probe leads to GND or something that might affect operation.
Quote from: boB on October 17, 2020, 10:25:23 PM
Quote from: qrper on October 17, 2020, 10:09:19 AM
Here's a bit of FYI
I an old analog guy, and I like to watch analog meters more than a digital display.
So i connected a analog meter to the same sense wires on the Whizbang jr so I could see the current flow on a analog meter. Apparently the load from the meter caused issues with the Whizbang, so I ended up placing a 100 A 75 mV shunt in the high side of the battery lead to the inverter.
Once the meter was removed from the Whizbang's shunt, everyone was happy.
I did add a 200mA fuse in the shunt's sense wires that fed the analog meter, since I was measuring current in the high side.
There was an old dead guy named Kirchoff that said current in and current out of a node had to be the same, so a shunt in the high side will read the same as one in the negative lead like the Whizbang.
It's possible the other equipment doesn't like the shunt the Whizbang is married to. I'd add another shunt to the battery neg lead just for the external equipment and see what happens.
Mike, wb8vge
That is surprising that some analog meter would make a difference at all. The resistance of a 500A 50mV shunt is 100 micro-Ohms. I doubt that your meter would be loading anything down unless you put it into current mode. THAT would be low resistance. It would have to apply some amount of load OR maybe some voltage to affect the shunt reading I would think.
What kind of meter was it ? Was it internal battery powered ? If externally powered, I might understand some kind of connection from one of the meter probe leads to GND or something that might affect operation.
BoB
It was (is) a 75mV analog meter. That meter required no power to operate.
I too thought it shouldn't have caused any issues, but when I opened another one, I found a resistor between the meter's coil terminal. I don't remember what the value was, and I'm guessing here, the meter may have been 200uA and the resistor was used to scale the movement to the required 75mV input. Of course, there was no documentation supplied with this Chinese meter.
Another issue was the scaling. The 500A shunt with the Whizbang and a 100A meter didn't provide much data. Even at 100A, the Chinese meter would barely move a quarter inch off scale.
The fix was to insert another 100A 75mV shunt in the high side of the inverter cable. Looking back, I don't know why I didn't put the shunt in the negative input to the inverter (the whizbang was in the negative lead) right at the battery.
The photo attached shows the 72mm DIN meters. The bottom right one is not doing anything. The bottom left is the one with the additional shunt added.
mike
Quote from: Vic on October 17, 2020, 10:24:25 PM
Ok, Thanks, just was curious.
The old Xantrex SW+ 5548s here weigh about the same -- 143-145Lbs in the box, and about 138 Lbs, or so without the packing. Could not come close to hefting them onto the wall, without help, and that was 15 years ago, at that.
Shipping is a killer these days.
Good luck, Vic
Vic,
You got that one right!
Once, way, way back, I had to send my 5548 back to trace. It wouldn't turn on. They replaced a fuse, charged me an amazing amount of money to replace said fuse, and then I had to pay shipping back to Ohio. I can't imagine shipping that bad boy again, let alone getting it off the wall.
That being said, and I don't want to take over this thread, but do you know of anyone that repairs these old Trace inverters? The one I have has been on 24/7 since January 2020. It's 18 years old. I'd like to get a backup on line, and I think i'll see Jesus before the Midnite Solar inverters get on the market.
mike
The
Quote from: qrper on October 18, 2020, 10:54:38 AM
Quote from: Vic on October 17, 2020, 10:24:25 PM
Ok, Thanks, just was curious.
The old Xantrex SW+ 5548s here weigh about the same -- 143-145Lbs in the box, and about 138 Lbs, or so without the packing. Could not come close to hefting them onto the wall, without help, and that was 15 years ago, at that.
Shipping is a killer these days.
Good luck, Vic
Jim Kerbel used to repair Trace stuff . You might check with him.
http://www.pv-systems.org/page/about-us
Larry
Vic,
You got that one right!
Once, way, way back, I had to send my 5548 back to trace. It wouldn't turn on. They replaced a fuse, charged me an amazing amount of money to replace said fuse, and then I had to pay shipping back to Ohio. I can't imagine shipping that bad boy again, let alone getting it off the wall.
That being said, and I don't want to take over this thread, but do you know of anyone that repairs these old Trace inverters? The one I have has been on 24/7 since January 2020. It's 18 years old. I'd like to get a backup on line, and I think i'll see Jesus before the Midnite Solar inverters get on the market.
mike
The
Yeah, way heavier than the Heart, and the Trace units it replaced. Since this heavy sucker went on the backplate before the E-panel I'm not sure it will even come off without uninstalling the E-panel. Does anyone have experience like that with the MNSMA-short backplate, and MNSMA-OG E-panel - will I have to take it all down to replace my inverter?
SMA support says the Sunny Island should not be hooked to the DC shunt when the MODBUS/Canbus communications adaptor is used. While not in the documentation from MidNite that came with this adaptor, nor mentioned anywhere in SMA's difficult to read manual to get this to work right during initial setup I should have:
a) #225.01 BatCurSnsTyp - set to NONE
b) #250.28 ChrgCtlOp - set to SMA
Quote from: Trukinbear on October 20, 2020, 06:07:23 PM
SMA support says the Sunny Island should not be hooked to the DC shunt when the MODBUS/Canbus communications adaptor is used. While not in the documentation from MidNite that came with this adaptor, nor mentioned anywhere in SMA's difficult to read manual to get this to work right during initial setup I should have:
a) #225.01 BatCurSnsTyp - set to NONE
b) #250.28 ChrgCtlOp - set to SMA
Good to hear that you dug into it with SMA and got to the root of the problem.
Larry
They are also replacing the SI6048 under warranty due to the damage from operating it like this for 14 months. I'm very lucky, though I'm not sure how lucky I'll feel trying to swap these out after it gets here.
Quote from: Trukinbear on October 20, 2020, 06:07:23 PM
SMA support says the Sunny Island should not be hooked to the DC shunt when the MODBUS/Canbus communications adaptor is used. While not in the documentation from MidNite that came with this adaptor, nor mentioned anywhere in SMA's difficult to read manual to get this to work right during initial setup I should have:
a) #225.01 BatCurSnsTyp - set to NONE
b) #250.28 ChrgCtlOp - set to SMA
Doesn't make sense to me that the SI would be running without a shunt, since it is in "charge" of the whole system and tells the Classics what to do.
The Classics would need to be on the SI side of the shunt (not the battery negative) but I do not understand why SMA would say no shunt.
There are all sorts of adjustments in the SMA menus as far as I remember.
The shunt is still physically there with the WhizBang Jr attached, and all power still flows through the shunt as it always has - BUT the sensor wires from the Sunny Island to the shunt are eliminated, and the Sunny Island is told there is no shunt (or it would shut off actually) and that it has SMA chargers connected instead of selecting DC coupled (even if it IS DC coupled) it needs to think the two Classic 250's are the non UL certified SMA DC-coupled chargers they don't sell in the States. It has acted screwy for 14 months, it seems to be behaving correctly now, just before they replace it. Any idea if the SI can be R&R with the E-panel in situ?
Funny thing, in the SMA manual it warned me that severe battery damage would occur if I failed to install, and properly calibrate the DC shunt, so I did... and shouldn't have it seems now. Nowhere does it mention any of this. I'm curious to know if you just haven't put very many of these in the field, or if everyone else found out this same thing from SMA support and didn't bother to tell anyone. Anyway, I hope this info is useful to someone other than just me.
We have shipped several of these systems now. I am not familiar with anyone else being told to disconnect the shunts from the SI probably because I'm not in the support department. I mentioned this (your situation) to the others and nobody has claimed this to be the case, yet.
I wish I could hear more about it and hopefully will.
Also not sure about the R&R part. Yet.
It could be one of those 'common knowledge' things where they were purchased by people who already knew what they were doing, or it could be that none of these systems are operating properly, and rather than appearing to just fail they just act erratically which people probably attribute to those German engineers at SMA. Their manual reads like the key-book for the Enigma machine. Yes, there are a ton of options, they just don't tell you much more than a cryptic abbreviation often with no verbiage about what the selections actually do, or more importantly why/what you need to change them for/to. Explanations of warning messages and failure codes are even worse. I did end up going to the SI6.0 manual for some slightly better-explained codes... I just have to trust they are the same codes carried over from the SI6048.
So, did the E-Panel with SMA SI and Classics come with with the shunts wired to the Sunny Island inverter ?
No, I bought the stuff from three or four different vendors. A short SMA backplate, and the twin classic side plate, the E-panel came with the shunt installed, but not with the leads to the Sunny Island (those were in the SI box). I installed the DC side breakers, WhizBang Jr, and a couple of busses for the PV...along with the MODBUS/Canbus adaptor in the E-panel, and now the three MNSPD's, and the MNBDM too. I'm afraid the E-panel will have to come off the backplate to R&R the SI.
It has been a few years but I was the one that worked with SMA on this project. We worked with Roy Dynghan and Kristen over at SMA. The SI is a very fickle beast on SOC and it uses SOC for everything (Not always a good thing)
What I know and have in my notes:
You can use the SI COMM for current calculations but SMA at the time didnt recommend it as the classics are not calibrated like a shunt. My personal system uses the shunt and an SI Comm but I set the SI up to follow the shunt not use the classics.
I suspect there is more than one way to skin the cat but thats how Roy had me set it up when we designed the SI COMM
Do your Classics, Sunny Island, and battery hydrometer all agree on your SOC? Mine NEVER agreed...
Curious how far back this was. I bought my SI last August and when it arrived it had old firmware, which I updated. Perhaps they changed something in the firmware update?
This is from SMA:
The battery SOC issues may be influenced by a few factors. For one, the battery SOC is recalibrating down to 20% due to low voltage. I've attached graphs of SOC and voltage to this email. Note the battery voltage dipping as low as 45 V at times. These drops correlate with the SOC recalibrations. SOC recalibrations can be caused by improper programming and/or weak battery cells. I've attached the SI Battery Management document to this email, which explains causes and remedies for SOC recalibrations in detail. Ignore the mention of programming the C10 capacity, as this only applies to non-US Sunny Islands. I recommend a few actions for addressing the SOC recalibrations.
Confirm the battery capacity is set to the C20 rate. If you are not sure if 986 ah is the C20 rate, please contact the battery manufacturer to confirm.
Your initial comment indicates that you have installed the Midnite Com Adapter for the SI, but the parameters show that you also have a shunt programmed. The SI can work with *either* the Com Adapter or a shunt, not both. If you want to continue using the Com Adapter, you must deactivate the shunt programming in menu 225 Battery Current Sensor. Additionally, to ensure proper communication to the Com Adapter, you would need to set menu 250.28 ChrgCtlOp to SMA. You can only change menu 250.28 while the system is in Standby.
Load-test the battery in order to determine if there are any weakened cells. I have attached a short article describing how to perform a load-test with a voltmeter.
My SOC was always within the margin of error yes. SMA has a SOC% and then they have a Margin of error % also.
Mine was often off by 50-70%