Weird Battery Bank graph, maybe one of the experts can decipher for me

DickyDck

Hello everyone! you guys were really helpful last year in getting my system stable, so I was hoping some more troubleshooting could happen. System has been great for a very long time, but recently it started doing the random glitch, where nice sunny day everything is working then the inverter drops to 0 for about 3-10 seconds, then climbs back up. I will recap my system here...

Schneider XW6848+
2 x MPPT 60-150
the Schneider PDP
Combox
16 Crown 6v AGM 220ah batteries, running 2 strings at 48v

No settings have changed since way before this time last year, roughly. 

Grid Support enabled
Grid Sell enabled
Load Shave off
Grid support Voltage set to recommended 64
Inverter charge voltage set to 52 at 2-stage
CCs Charge voltage set to 53 at 3 stage (I can't remember where I read it, but it was suggested to set the CCs higher than the inverter)
GVS off
AC Coupling on

I happened to be looking around at other threads, and I saw someones "normal" battery graph, and mine looks absolutely nothing like it.

I truly have no idea what any of this means, but since everyone elses normal line graph looks nothing like mine I'm guessing something is wrong.

DickyDck

mcgivor

Looks to me like the grid is charging almost every hour once the voltage drops to around 53.4V, which rapidly recovers to 58V. Dose this reflect in your settings?, you might want to program a charge block between 16:00 and 07:00 to prevent this unnecessary charging.

DickyDck

mcgivor said:

Looks to me like the grid is charging almost every hour once the voltage drops to around 53.4V, which rapidly recovers to 58V. Dose this reflect in your settings?, you might want to program a charge block between 16:00 and 07:00 to prevent this unnecessary charging.

Hmm, ok let me try that. I will let it run over the weekend and see if that stops the spiking. Thanks! Can you take a looksy at this chart? this is one showing the Solar Panels producing between 5kw to 6kw, then dropping to 0, then rinsing and repeating for hours.

DickyDck

Its almost like it is hitting some sort of high voltage/wattage cutoff limit but there is nothing in the error/warning logs, and it isn't doing the 5 minute cooldown thing

mcgivor

What was the weather during this capture, intermittent clouds can cut production, then rapidly return once passed.

DickyDck

Strange how I kind of see new things as I post them here, you can see where the sun creeps above the tree line at around 0730, but even then it does the create solar power, drop to zero, resume solar power, drop to zero, even under 1kw of power...so that kind of debunks the hitting of some wattage high limit, but not sure where to see voltage/amperage readings in the combox.

DickyDck

mcgivor said:

What was the weather during this capture, intermittent clouds can cut production, then rapidly return once passed.

bright sunny all day yesterday and today, these things started happening maybe monday or tuesday. if the charge block doesn't make any changes I may go full reset to factory and treat it like MS Windows lol

mcgivor

In the PV power display, have you zoomed in near the 10:00 h area to see if in fact there are a series of rapid fluctuations that appear solid at the normal resolution, if so, it could be a bad connection is causing intermittent collapse in production. This is something I've experienced with a failed mp4 connector working fine until getting hot due to high resistance under load, the connector itself was cracked.

DickyDck

mcgivor said:

In the PV power display, have you zoomed in near the 10:00 h area to see if in fact there are a series of rapid fluctuations that appear solid at the normal resolution, if so, it could be a bad connection is causing intermittent collapse in production. This is something I've experienced with a failed mp4 connector working fine until getting hot due to high resistance under load, the connector itself was cracked.

Affirmative, a crapton of 6kw to 0 to 6kw. Can you elaborate on the MP4 connector? is this in the inverter, at the combiner box, or someplace else? I assume since you have seen one cracked it would visibly be easy to see?

mcgivor

The mp4 connectors are what are typically used to interconnect the panels, I bought some panels which had bad connectors, one melted, one was cracked, pic above, was almost invisible and only discovered when I removed all of them and butt spliced the panels together.

DickyDck

mcgivor said:

The mp4 connectors are what are typically used to interconnect the panels, I bought some panels which had bad connectors, one melted, one was cracked, pic above, was almost invisible and only discovered when I removed all of them and butt spliced the panels together.

Ahh gotcha! those are easy enough to inspect! so the connecter cracking/melting would affect the electrical connection of the contacts inside? I suppose a critter could also have nibbled on one, the back of my solar array is a small forest. Thanks a lot for giving me a starting point!

BB.

If you have/can get an AC+DC Current Clamp DMM... It is very nice for comparing current flow... Several strings of solar--They should all be very close to matching current flow (typically within 5-10% or better). If you have parallel strings in the battery bank, again, look for "matched" current flow (here, within 50% or better is probably what to expect).

With the voltmeter, checking battery bus, charge controller input and output connections, inverter DC connections, etc. all helpful.

Checking for warm spots in wiring. A hot battery connector usually is loose/dirty/corroded... Note be careful if you are using your hand to check temperatures--A bad connection could get "burning" hot.

If you ever want another "toy"--The thermal cameras are getting pretty reasonable pricing:

https://www.amazon.com/s?k=thermal+camera+for+android&ref=nb_sb_noss_2

-Bill

DickyDck

BB. said:

If you have/can get an AC+DC Current Clamp DMM... It is very nice for comparing current flow... Several strings of solar--They should all be very close to matching current flow (typically within 5-10% or better). If you have parallel strings in the battery bank, again, look for "matched" current flow (here, within 50% or better is probably what to expect).

With the voltmeter, checking battery bus, charge controller input and output connections, inverter DC connections, etc. all helpful.

Checking for warm spots in wiring. A hot battery connector usually is loose/dirty/corroded... Note be careful if you are using your hand to check temperatures--A bad connection could get "burning" hot.

If you ever want another "toy"--The thermal cameras are getting pretty reasonable pricing:

https://www.amazon.com/s?k=thermal+camera+for+android&ref=nb_sb_noss_2

-Bill

I've been eyeballing thermal cameras for a while for "fun" experiments anyway, so now I have a more usable reason to get one. I have a cheapo current clamp but it works, so I just wrap that around the solar cables?

BB.

One cable at a time. The clamp measures total current through clamp.  +5-5=0 if you run both wires from a set through the clamp.

Also, need a DC current clamp meter. An AC only meter will not work on DC current.

-Bill

DickyDck

BB. said:

One cable at a time. The clamp measures total current through clamp.  +5-5=0 if you run both wires from a set through the clamp.

Also, need a DC current clamp meter. An AC only meter will not work on DC current.

-Bill

I just figured that out! mine is an AC meter, and I was like...why the fark is this not working!!!! Learning experiences are fun! You guys rawk the mind, and smacking my wallet but tools are an investment!

DickyDck

Quick update
I tweaked the charging numbers a bit lower, my bank seems to hover at 50.7 so I set the inverter charging below that and left the CC numbers higher. THe graph seems to have evened out a bit at night and during the day.

Yesterday I left the house early and came back late and say that my numbers though consistent were barely bringing in 700-1000w all day, I hit the disconnect to the array and flipped it back on and everything went back to normal for 17:00-ish and I started producing around 3-3.5kw. Will monitor some more to see if that happns again

waiting on amazon to send me my DC clamp to test the solar strings

DickyDck

Just an update, didn't want to leave everyone wondering. I had to return the clamp meter thing since it didn't work, waiting in a replacement to see if I just got a dud or whatnot. Should be coming today, but it is dreary and no sun today but tomorrow is supposed to be nice and bright for testing!

DickyDck

ok so tested everything I could, it seems that the battery bank may just be losing its charge capabilities. I've adjusted my charging voltages and amperage and it seems to have leveled off and the graphs are looking normal-ish with a gradual sloping dome rather than a roller coaster. I have to go over to the other forum and find the mathematical equation for AH to Amps to voltage charging, maybe I borked that during one of my factory resets....

BB.

What exactly are you looking for math wise? The general equations are:

• AH * % rate of charge = Charging Current
• 440 AH * 0.10 rate of charge = 44 Amps
• Power = Voltage * Current
• Power (Watts) = 59 volts (actual charging voltage from ~48 vols to ~59 volts charging) * 44 amps = 2,596 Watts into battery bank
• Say battery at 60% State of charge
• 440 AH * 0.60 state of charge = 264 AH left
• 440 AH * 0.40 state of discharge = 176 AH to refill
• 176 AH / 44 Amps charging = 4 hours charging + 4 hours absorb = ~8 hours "on charge" to fill

Note that you are charging at 44 amps until battery bank is ~80% capacity, then gradually to less than 1% rate of charge as bank approaches 100% SoC. Absorb time roughly 2-6 hours... ~2 hours if 75% SoC, and ~6 hours if 50% or less SoC (very rough numbers for lead acid batteries).

-Bill

DickyDck

that was it! maybe it was you in the other forums that provided the math part. I have to double check my settings for absorption, I think I had it higher than 6 hours

GoldenGate

Hi,

You and I have experienced some of the same issues, we run similar equipment, and I've a question for you, perhaps you can help.

First off, you've seen your inverter produce at maximum KW, then drop to zero, then max it out again, then drop, etc.

I saw the same when my system was initially installed, we resolved it with a software upgrade. 

Next, you've seen the inverter cook the batteries overnight - it's running an absorb cycle every 60-90 minutes. 

I'm still dealing with this issue.  I'm unclear if you've resolved or not? If so, how have you resolved it?

My workaround at this point is to disable the inverter charger, only charge from the MPPT.

This works well, except when the panels are covered with snow for days on end, as they were in March.

When that happens, I can enable the inverter charger from the SCP, run an absorb cycle and then disable.

Crude, but effective.

My issue seems to be that the interface provided by Schneider (Gateway, Local Insight, Cloud Insight, SCP) does not allow the recharge volts to be changed.  When the system was new, the batteries didn't drop below their default recharge voltage overnight, so the problem didn't occur.  When the batteries did begin to drop below the default recharge voltage overnight the inverter began running absorb cycles and cooking the batteries, which exacerbated the problem.  I didn't catch on to it for a few months, so damage done. 

Question - can have you resolved your overnight absorb cycle issues? If so, how?  In particular, were you able to set the recharge volts in the interface somewhere?  If so, where?

Background on my issue ended up here:

https://forum.solar-electric.com/discussion/356090/schneider-xw-pro-6848-wont-qualify-generator-on-ac2#latest

DickyDck

GoldenGate said:

Hi,

You and I have experienced some of the same issues, we run similar equipment, and I've a question for you, perhaps you can help.

First off, you've seen your inverter produce at maximum KW, then drop to zero, then max it out again, then drop, etc.

I saw the same when my system was initially installed, we resolved it with a software upgrade. 

Next, you've seen the inverter cook the batteries overnight - it's running an absorb cycle every 60-90 minutes. 

I'm still dealing with this issue.  I'm unclear if you've resolved or not? If so, how have you resolved it?

My workaround at this point is to disable the inverter charger, only charge from the MPPT.

This works well, except when the panels are covered with snow for days on end, as they were in March.

When that happens, I can enable the inverter charger from the SCP, run an absorb cycle and then disable.

Crude, but effective.

My issue seems to be that the interface provided by Schneider (Gateway, Local Insight, Cloud Insight, SCP) does not allow the recharge volts to be changed.  When the system was new, the batteries didn't drop below their default recharge voltage overnight, so the problem didn't occur.  When the batteries did begin to drop below the default recharge voltage overnight the inverter began running absorb cycles and cooking the batteries, which exacerbated the problem.  I didn't catch on to it for a few months, so damage done. 

Question - can have you resolved your overnight absorb cycle issues? If so, how?  In particular, were you able to set the recharge volts in the interface somewhere?  If so, where?

Background on my issue ended up here:

https://forum.solar-electric.com/discussion/356090/schneider-xw-pro-6848-wont-qualify-generator-on-ac2#latest

What is your Inverter charge voltage set at? what I did to stop the overnight cycle was setting the recharge voltage 0.5v below where the batteries seem to level off at over night. This requires some testing, but you may already have the numbers since you have turned off Inverter charging and only using CC charging. overnight, what is your lowest voltage seen in your graph? try setting the Inverter charge setting maybe 0.3 under that, turn back on our inverter charging and test for a night or two. I agree only using CC charging in autumn spring and summer is fine, but when there is snow on your panels it isn't the best route to go. Let me know how you make out, my problem has been fixed by adjusting the voltage. I'm not sure if my AGM batteries have different behavior than standard Lead Acid batteries or not, so keep that in mind. I have no idea what Lithium batteries act so I definitely can't help with those things.

GoldenGate

Thanks for the response, DD.

My issue is that no where in the interface (SCP, gateway local or cloud) can I set the recharge volts. 

Question to you - where did you set the recharge volts?  If possible, could you attach a picture or a screen shot?

I'm trying to pin Schneider down on this one, but so far no luck. 

-dws

DickyDck

Oh I see, I have a Combox which gives me the web interface, but the SCP “should” have the setting somewhere. When I get back later I’ll see if I can figure out where in the settings. I imagine it would be in the “advanced” area and there was a certain way to unlock that ability but it has been so long since I’ve tried it since I bought the combox it made things much easier. I’ll get back to you this evening with what I find.

DickyDck

https://www.solarelectricsupply.com/fileuploader/download/download/?d=0&file=custom%2Fupload%2FSchneider-Conext-XW-operation-guide_eng.pdf

Section 3-6 under basic settings you can set the change voltage using the SCP console

@GoldenGate