Schneider XW6848+ and MPPT-60 are displaying different battery voltages

QuintanaRoo

Hi, I have a Schneider XW6848+ with MPPT-60 charge controller, with SCP and Conext box, w/ 8x Rolls 375aH batteries (48V)
The voltage that the MPPT-60 show and that the XW show are different by about 5-6V, are they not supposed to display the same batter voltage (there is only 1 bank)?
The system doesn't seem to be charging the batteries correctly, could this be the problem?
Help, ideas?

Thanks!!!

mcgivor

What size are the conductors between the controller and battery, how long and what current is the controller displaying? Sounds like a cronic voltage drop problem. Do the conductors between the controller and battery get hot by any chance? 

QuintanaRoo

Here is the screen from the Conext

QuintanaRoo

There is #8 from the controller to the batteries, about a 2m (6') distance.  I don't notice them get hot but will check throughout the day. I have 12X 250W panels, charge amps can be 20A+.
It seems like the controller voltage is correct when I measure the voltage at the batteries and at the terminals of the controller they are the same, it is like the XW is reading 5V higher and I don't know where it is getting that voltage reading from?
Any advice is appreciated

mcgivor

Looking at the figures, this is under battery load, no PV input, what time of day was this snapshot taken? The PV input voltage is 110V not changing, inverter using battery -3.9A, late in the day, or early morning? 

QuintanaRoo

Yes, that was in the evening, here is one at 10:30am, the sun is starting to come around.

Dave Angelini

This can't happen !

unless something bad happened... So give some history like how old, lightning protection? Maybe a picture? Gen set surging?

QuintanaRoo

That's what I can't figure out?  I was away for a couple of months and when I came back I noticed this, so no idea what happened.  Not sure how to troubleshoot it... weird...
How can this be?
Any advice or comments are appreciated

mcgivor

What settings are used on the controller ? Seems odd the voltage discrepancy, try a cold reboot allowing a few minutes to discharge capacitors, nothing to loose. My day has ended, different time zone, good night.

QuintanaRoo

Thank you, I appreciate any comments or advice as I am fairly new to this.
Yes, I will do a cold re-boot....
Good night

mike95490

Open the epanel and look (don't touch) the wires.  I had a somewhat similar problem from a cable setscrew loosening up after 3 years, and causing a high resistance.
Melty Crispy Wires:
https://www.facebook.com/media/set/?set=a.654873231252800&type=1&l=f5bcf8e0a7 

Estragon

QuintanaRoo said:

There is #8 from the controller to the batteries, about a 2m (6') distance.  I don't notice them get hot but will check throughout the day. I have 12X 250W panels, charge amps can be 20A+.
It seems like the controller voltage is correct when I measure the voltage at the batteries and at the terminals of the controller they are the same, it is like the XW is reading 5V higher and I don't know where it is getting that voltage reading from?
Any advice is appreciated

Charge amps might be 20a at string voltage to controller, but more like 60a from controller to batteries at bank voltage.  Not likely the problem, but #8 is a bit on the light side IMO.  A loose/corroded connector + light-ish wire might be contributing.

I don't know Schneider well, but it seems odd to me that the screens both show CC current (amp) flow, but zero watts.

Some gear has a voltage offset to adjust for drop to ensure proper actual charging voltage.  Any chance this was set missing a decimal (eg 6v s/b .6v)?

QuintanaRoo

I did a hard reboot, disconnects AC and batteries via breakers, let sit for 30 minutes.  Started back up and still the same, the XW is reading about 5.5V higher than the MPPT.  I think that the MPPT is correct, what would cause the XW reading to be higher?

Dave Angelini

You need to measure the voltage. Is the inverter working?
If you are anywhere near QuintanaRoo, lot's of lightning there! Do you have SPD's? As was mentioned, take everything apart and use your eyes and nose to inspect.

We use to anchor off Tulum. A very special place!

QuintanaRoo

The inverter is working is working, when the measured voltage at the batteries is when the MPPT shows, I don't know where the Inverter is getting it's reading for the battery voltage and it is 5-5.5V higher?  I can't find any offset parameters in the inverter?  

Dave Angelini

There are no user offsets on XW or system. You need to state what you have done. Go thru each of the suggestions again and check them off. The xw and mppt get voltage from the wiring.

I do not understand your  last #15. Say it in a different way please!  Do you have a voltmeter? You can take 5 minutes and do this right or ?

QuintanaRoo

With a Voltmeter I measured the voltage across the battery terminals, then across the BAT terminals in the MPPT, then across where the main battery cables (#2) connect to the breaker inside the XW case, all reading are equal and agree with the voltage shown on the MPPT (currently 55V).  On the SCP, the XW shows a voltage about 5V higher (60.5V). 
I've opened everything up and checked connections, crusty wires, etc. and everything looks in tact.
I'm confused...  Is there anything else I can check or troubleshoot? 

Dave Angelini

Ok thanks! Is the mppt working? Still daylight in quintana right?

Are there any historical faults or warnings in combox? I assume you would have seen an active fault or warning, right?

 If the SCP and combox agree on 5v higher on XW then I would disconnect all of the network cables and reboot without them. After it is up, I would plug the SCP into the xw with just those 2 devices and terminate this network.  see if it changes?

Estragon

Just a thought - 5v sounds like it might be a PCB rail voltage / voltmeter reference voltage?

QuintanaRoo

Yes, the MPPT is working and seems to be charging.
No historical faults or warnings in combox.
I disconnected the MPPT completely and the voltage on the XW still showed high.
Yeah, it seems to follow the XW follows the MPPT battery voltage but is always 5.5V higher.  I think this is causing problem because when I run the generator to equalize it is not reaching high enough voltage through the XW?
I'll try disconnecting the network cables and rebooting....

rpvietzke

One thought... The MPPT 60 charger expects its own negative to the panels. It is NOT okay to tie the panel's negative to the battery negative. I had an issue with dual charge controllers when I used the common bus bar for negative in the combiner outside that caused the MPPT to misread/display and also undercharge. Making sure the Negative and Positive both had clean runs to the panels made all the difference in my setup. The fact you show 110V on the panels, but 0 watts input and some output make me wonder if this could be related.

Dave Angelini

rpvietzke  It would log this on combox in history, but nice try

What make is your distribution panel? Is there one? I say this because the stock 250 amp Schneider breaker in their panel only shuts down the XW. The DC bus stays on and maybe you are not interrupting DC to the mppt? Just checking.

QuintanaRoo

Hi, the panel is Schneider as well.
It is night now and I just unplugged everything from the MPPT, the BAT and the PV, so the MPPT is off for sure. I also disconnected the network cable from the MPPT and AGS and terminated on the XW....... and the XW is still reading 5.5V higher than the actual battery voltage measured on the posts with a volt meter..... uggggh?

mcgivor

Perhaps there is a glitch in the firmware, has this been updated?  I would suggest contacting support, often issues are known, baring any termination problems it sounds like a calibration problem of sorts.

QuintanaRoo

Thanks I have downloaded installed all new firmware, still the same issue.
I tried emailing Schneider but after a day and a half only got a mediocre response, is there a tech support number?

QuintanaRoo

rpvietzke said:

One thought... The MPPT 60 charger expects its own negative to the panels. It is NOT okay to tie the panel's negative to the battery negative. I had an issue with dual charge controllers when I used the common bus bar for negative in the combiner outside that caused the MPPT to misread/display and also undercharge. Making sure the Negative and Positive both had clean runs to the panels made all the difference in my setup. The fact you show 110V on the panels, but 0 watts input and some output make me wonder if this could be related.

Hi I did check this and the negative from the panels was going to the negative DC ground, I changed that so now the W are showing on the PV on the conext, but still the Voltage is 5.5V different?

mcgivor

QuintanaRoo said:

Thanks I have downloaded installed all new firmware, still the same issue.
I tried emailing Schneider but after a day and a half only got a mediocre response, is there a tech support number?

Schneider tech support is so hit and miss, I asked a question, waited two and a half months for an answer, followed up with another email, they said will get back as soon as possible 3 days later nothing. Other times been excellent, prompt response..... like Morningstar is, always.

Makes  me have second thoughts about my choice of equipment, the first cooling fan failure was 6 months after installation, they said ship it in for replacement under warranty, way more than 10 times the cost of a replacement fan, not to mention down time, second fan lasted 3 months longer, i replaced them with cheap commonly available fans which have outlasted the original ones, probably voids warranty but honestly I don't care, there are other brands at much lower cost which are available , even my $250 2000W PSW "no name" brand inverter has been on and running twice as long without an issue, using a fraction of the standby energy.

Sorry about the rant, it's actually good equipment, let down by by poor service at times, all news is bad news, but they tend to bring it upon themselves at times.

Sincerely I hope you have better results than I've had as of late with support and your issues are addressed 

Dave Angelini

If you were my client I would lend you a spare. I would also tell you to sell the old one or use it as a spare. There is not much that is worse than a inverter with issues offgrid. You never did say if you have surge protection and that is how I think this happened. Either the genset or the thunderstorms can do this easily.

 The firmware for an offgrid XW has never been an issue. I still have one from 2007 running fine.

I do find it weird that you did not see a warning in the mppt from the wiring error. What did you change?

rpvietzke

Following up on bringing the negative from the panels needing to wire through the MPPT; glad that made some small progress. This was a mind tease for my dual MPPT setup for months and I also thought it had been lightning and had gone to the trouble of RMAing and swapping the second unit only to have the same problem. It was at that point we figured out the negatives from the panels needed to be isolated and have a clean run in to the MPPT separate from the other panel string and battery negative.

Given that it seems like your MPPT voltage is correct, but the XW is not... One other question. The display seems to think that the XW doesn't know the battery temperature? It shouldn't matter for voltage, but do you have a BTS connected on the XW? I thought I read somewhere that if there was one BTS in the system every other component could read it, so it is sort of weird the display says it doesn't know the battery temp for the XW? Maybe that is another indicator something is wrong with the XW control board?


Rob

rpvietzke

Dave Angelini said:

rpvietzke  It would log this on combox in history, but nice try

What make is your distribution panel? Is there one? I say this because the stock 250 amp Schneider breaker in their panel only shuts down the XW. The DC bus stays on and maybe you are not interrupting DC to the mppt? Just checking.

Dave -
Boy, I wish the combox could log wiring issues like this, but there were no errors or other issues.

This was a mind tease for my dual MPPT setup for months and I also thought it had been lightning that fried one unit. The schneider folks tried to troubleshoot it and had gone to the trouble of RMAing and swapping the second unit only to have the same problem. (And then I had three, so I swapped the first unit two. Same results.) It was at that point we figured out the negatives from the panels needed to be isolated and have a clean run in to the MPPT separate from the other panel string and battery negative.  Apparently the MPPT's sense on the negative side from the panels to run their charging algorithm and when the two sets of panels shared a ground bus in the combiner box, it messed up the 2nd controllers ability to do its thing. Since we figured this out and gave the 2nd array a direct feed to the MPPT(2), its been working absolutely great.

Rob

QuintanaRoo

rpvietzke said:

Following up on bringing the negative from the panels needing to wire through the MPPT; glad that made some small progress. This was a mind tease for my dual MPPT setup for months and I also thought it had been lightning and had gone to the trouble of RMAing and swapping the second unit only to have the same problem. It was at that point we figured out the negatives from the panels needed to be isolated and have a clean run in to the MPPT separate from the other panel string and battery negative.

Given that it seems like your MPPT voltage is correct, but the XW is not... One other question. The display seems to think that the XW doesn't know the battery temperature? It shouldn't matter for voltage, but do you have a BTS connected on the XW? I thought I read somewhere that if there was one BTS in the system every other component could read it, so it is sort of weird the display says it doesn't know the battery temp for the XW? Maybe that is another indicator something is wrong with the XW control board?


Rob

Yes, thanks again, I felt like I had one small win, althought losing the war, LOL
I have a BTS hooked up to the MPPT (yes I thought that all units were supposed to see one input - but not here).
I did try moving the BTS to the XW BTS input and then the XW showed the correct temperature and the MPPT was N/A and the voltage difference between the two were still the same (I thought the voltage difference may have been due to a temperature compension , but no).
Still waiting for my daily one sentence reply from Schneider.....