Conext XW+ 6848 trouble with the generator

M Cuz · April 2015

Hi, I just installed a new Conext XW+ 6848 NA but I have trouble with the generator. I have a type 2 generator connected to the inverter and I’m using a SCP with a AGS. The problem starts when the generator kicks in, I can see the number going from 10 to 100 in just seconds and then the inverter goes to stand by(- - - ), after a few second it will start the charging again and the number keeps saying that the charge is 100% in just seconds and then the loop starts all over again.

Any help will be welcome

BB. · April 2015

Welcome to the forum!

I am not any sort of expert in these off grid systems... But my first question would be the Battery Connections. Are the wires well attached (connector screws torqued properly)? What gauge/size of copper wiring are you using (battery connections, battery to DC panel, DC Panel to inverter, etc.)?

It sounds like the DC Bus voltage is not stable (poor connection and/or too small of diameter wiring).

Does the inverter work otherwise (i.e., can you turn on the inverter and run some subtancial AC loads--Like a 1,000 Watts or more of electric heater--as a simple load)? Can you measure the battery bank voltage and the DC Voltage at the Inverter's DC input?

Anyway, my first guesses.

Also, what size/type battery bank do you have? How many series/parallel batteries? With Lead Acid batteries, you need to get those charging so they do not excessively discharge and sulfate. Do you have some sort of good quality hydrometer to measure specific gravity?

-Bill

SkiDoo55 · April 2015

As B.B has requested more information on your battery bank capacity. Will determine what charging limits need to be set with the SCP. Wiring to/from batteries to inverter. Will need the capacity Watt output of your generator. Can effect Gen/Support settings if they need to be limited. Breaker sizes, need to be set thru SCP. State of Charge of battery bank, if charged or close may be throwing too much current at them, voltage rise to cutout, then voltage drop and then charge again. charging parameters need to be tailored to Bank Capacity, need a pretty large bank to handle the 140 amp DC charging of the 6848 charger.
Lots of adjustability built into the Inv/Charger just need to be adjusted from Defaults set at factory.

M Cuz · April 2015

Hi, guys, first thanks for your help, now I have two battery banks each with 8 six VDC batteries in series and both of them connected in parallel for a 48 vdc battery bank. Wiring from and to the batteries is gage #2 with very short distances. My generator can go up to 8500 k peak and 6500 on a normal run. Everything works fine, on a sunny day my PV array produce enough energy to run one 7 amps 220 VAC water pump, which draw 20% of the 6848 capacity, and keep the batteries charge. Forgot to mention I’m a farmer, I have a 10,000 square foot hydroponic system.

Thanks in advance..

BB. · April 2015

What is the Amp*Hour (20 hour rate) of the batteries/battery bank?

Do you have a solar array/AC utility power?

Most of these inverter/chargers can be adjusted. Maximum DC Charging current (sometimes entered as maximum AC current for charging--Confusing). Also, there may be an AC1 and AC2 input. AC1 is generally for utility power and AC2 is a wide range (frequency/line voltage) for Backup AC genset input.

Sometimes what happens is the line frequency (generator RPM) varies so much that the inverter/chargers will have a difficult time "qualifying" the frequency (+/- 0.5 Hz vs +/- 3-5 Hz) or line voltage.

-Bill

SkiDoo55 · April 2015

XW charging can be controlled via setting the limit in percentage of the 140 amp capacity of the charger. Your 8500/6500W generator can drive it to that output. Take a large bank to require that. Was the bank size entered into XW during setup. AC2 breaker size entered. You can set the amp value that you want to be the MAX current drawn by the XW from the generator. As B.B. Ask'd need the bank capacity to help suggest a setting for charging.
I would also, suggest that you change out the #2 ga wire with #4/0 ga wire and that is recommended not to be greater than 10 ft by Schneider for that inverter, with a 250 amp breaker.

M Cuz · April 2015

BB

Hi, my amp hour rate is 140, I have a solar array to charge the batteries and AC! (power company, it will be disconnected as soon as my generator works) no AC2. On the test I did the AC! Was disconnected only PV arrary and generator were connected.

Skidoo

I do not recall enter the battery bank size on the XW or AC2 breaker size.

Thanks

BB. · April 2015

A 140 AH battery bank (flooded cell type) is a awfully small battery bank for a 6.8 kWatt AC inverter.... In general, if you plan on running the inverter at full power (6.8 kWatts), the battery bank should be closer to 680 Amp*Hour @ 48 volt capacity.

And the rate of charge should be something around 14 amps to ~28 amps @ 48 VDC or so for that size battery bank.

I am not sure, but that size inverter-charger can probably do something near 100 amps of battery charging current... Way to much for such a small battery bank.

Are you sure your battery bank is 140 Amp*Hours @ 48 volt capacity? Maybe there is some confusion about what I am asking about?

-Bill

SkiDoo55 · April 2015

He might have 280 amp/hr think he said he had 2 parallel strings? XW is capable of 140 amp charge output. His charger settings need to be set to 10 to 20 percent. Set in percent of charger capacity. Agree needs bigger batteries higher capacity batteries. I have 370 a/h @ 24 VDC on a XW 4024 and if I was using on Off grid then my battery bank is way to small. Mine is for occasional essential power when grid goes down. Not very often 3.5 hr total so far this year none last year. Also, need to set total bank size thru setting or SCP has effect on absorb times end current etc.

M Cuz · April 2015

Hi guys; That is right I have 2 string of 8 6vdc batteries and with that I run 1 water pump(8 to 6 hours a day) that draw 7 amps at 220 vac. I know that my battery bank is small, but the idea is to grow my hydroponic and at the end I’ll be needing the power to run 5 pumps so when the time and $$$$$ comes I’ll increasing the battery bank size. I’ll configure SkiDoo’s settings today and let you know the outcome.
Thanks for your time

SkiDoo55 · April 2015

Due you have generator support turned on? You can set the limit on what the inverter will pull as max, charging and pass thru to loads. It can deliver power to load and charge at the same time. I would target that setting to be @ 80% of the 6500W rating to keep the frequency and voltage regulation getting large surge loads to it. You can adjust your charger settings to what will provide stable operation. Best to start low and work up to what provides the best results. Charging current should be around the 10% of amp/hr capacity of the bank. Bulk charge with gen and let solar finish it. B.B and others can offer more experience with the daily care of charging and help with the setting to maintain battery health as they live on the battery daily. Due wish the XW manuals had more and clearer explanation of the settings and what hey do. Could solve a lot of mistery and frustration, complaints about them. I love how mine is working. You can send request to tech support, they normally get back within 24-48 hr via email.

BB. · April 2015

Actually, I am on Utility/Grid Tied--I do not have any off grid solar... Just a small backup genset (if I ever need it).

-Bill

SkiDoo55 · April 2015

BB. wrote: »

Actually, I am on Utility/Grid Tied--I do not have any off grid solar... Just a small backup genset (if I ever need it).

-Bill

I stand corrected for some reason thought you were off grid. My XW is set grid support/sell. Every couple of weeks I simulate a grid failure (shut off AC1 breaker) and let it feed the panel from inverter to exercise batteries. Guess I need to figure out who I was thinking of that is off grid.

BB. · April 2015

No problem... I try to help everyone (within my limitations).

-Bill

SkiDoo55 · April 2015

M Cuz wrote: »

Hi guys; That is right I have 2 string of 8 6vdc batteries and with that I run 1 water pump(8 to 6 hours a day) that draw 7 amps at 220 vac. I know that my battery bank is small, but the idea is to grow my hydroponic and at the end Ill be needing the power to run 5 pumps so when the time and $$$$$ comes Ill increasing the battery bank size. Ill configure SkiDoos settings today and let you know the outcome.
Thanks for your time

Any update? Checking to see if adjusting the settings enabled the gen to stay on and supply power to loads and charger.

mike95490 · April 2015

A new thought,
Connect your generator to AC2 (which is where it is supposed to go, not AC1 which is Grid) Use the SCP to program your total battery AH size (2 parallel 48v strings, maybe about 300Ah your post was not real clear) You should have about a 600ah battery to support that size of inverter. Then use the SCP to program AC2=40A, GEN support to 25A, GEN Support Plus Enabled, and max charge rate 50%. (you can see some example in Col D below, I have to remind myself of the settings when I reboot). All these settings are in different menus on the SCP, and I think some are in the Advanced menu that needs a 2 button press & hold to enter.
Deep in the manual, are the definitions of the setting meanings. Some are AC L1 & L2 some are AC L1, some are DC, Some have internal 20% derate, But what I gave is 2x what my 3Kw genset is happy with, so your 6Kw genset should be fine too. Get it working then start tweaking it. The Combox comes in handy to see the actual loading in real time, and I use the SCP to tune things.

Oh, and 2ga wire seems too small for any battery connected to the inverter.

Attachment not found.

SkiDoo55 · April 2015

Schneider does not recommend Gen Support Plus being "ON"with a generator over 5KW size. Recirculating currents.

Dave Angelini · April 2015

SkiDoo55 wrote: »

Schneider does not recommend Gen Support Plus being "ON"with a generator over 5KW size. Recirculating currents.

True but the user should try it as this can be difficult to get going offgrid with a hybrid inverter like the XW. When it was new in 2007, it was the thing that made me give up on generators and go completly solar. I have many customers who live in places that need a generator or they just have not had the time to learn how to use less energy when solar weather is bad.

In some cases I just tell the person set the incoming AC2 amps to below the gen spec, widen all AC specs to max, and set the charge percentage to keep any AC loads from causing problems. Also the first hour should be for battery charging if you have a 6KW or less generator. Watch the DC amps on the SCP start dropping, it is telling you that the batteries are charging and there will be more power available for AC loads.

The old joke, there are two kinds of people, those who want solar and those who want more.

Aimsmall · September 2017

Hoping not to hijack this thread, but I'm having a similar, but inverse issue with a 6848. I've got 1000 ah @48 vdc on 4 strings of 8 6 volt batteries, charging well on PV, but since I need to bring the other array online, I'm trying to get generator charging operational in this off grid system. Connecting the Gen as prescribed in the wiring diagram, through the 60a breaker in the PDP, when AC power is applied, then qualified, the unit switches to charging, and amps (per the LCD) climb steadily to over 100, bringing the Gen to its knees, then and internal breaker or relay opens, and it stops trying to use the incoming AC. From what I've read in this thread, Gen support may resolve this issue. Am I on the right track?

mcgivor · September 2017

Always best to start a new thread specific to your system including as much detail as possible, generator capacity is essential to make a suggestion, from limited information, 100A at 48V+ is 4.8 Kw, so the generator would have to be larger than this value, perhaps 30% larger , ~6.5 Kw.

Aimsmall · September 2017

> @mcgivor said:
> Always best to start a new thread specific to your system including as much detail as possible, generator capacity is essential to make a suggestion, from limited information, 100A at 48V+ is 4.8 Kw, so the generator would have to be larger than this value, perhaps 30% larger , ~6.5 Kw.

I realized that this was an old thread, and did add this question to a thread I already have going on the myriad issues I've encountered so far: http://forum.solar-electric.com/discussion/352481/fried-xw6848#latest

Dave Angelini · September 2017

When in doubt read the manual? It is not the 60a breaker that are concerned with but the XW AC settings screen and its "breaker size setting.

ernievt · January 2021

I apparently just solved this by going into advanced settings and changing the advanced charge rate to 50% as shown below. This was a first try and not a fine tune. For now, it is working, so we are happy. We pump water so have left the water pump off until the batteries get up to snuff. I should further explain that my 11.5 kw Kohler standby generator went sick and hard wired a Honda EB5000 for the back up until the parts come in for the Kohler. Most everything is a setting. Yes, the manual could be better, but the product remains tops in my book.

Image: https://us.v-cdn.net/6024911/uploads/editor/ne/0vlo87qrwfek.png

Dave Angelini · January 2021

You can get the same effect by going down to AC2 Breaker setting and lowering it to the actual circuit breaker size on the Genset.
It actually is better for some gen situations. Yours is still at 60 BTW.
It is all about the strategy you use and they can all be very different.

I have been telling Xantrex when XW came out to have firmware just for offgrid. It would make configuration so much easier as you would not see all of the grid choices. Schneider has not listened either and so we have this. It is the same with Radian at Outback also.

Good Luck ! Where is home?

ernievt · January 2021

Hi Dave,

I will try the AC2 setting this spring. It's probably a better solution. Thanks. The house is off grid in Vermont where my son is spending the Covid winter (usually NYC) and he is more technically savvy now after this experience. My brother (next door neighbor) has the same unit, we both installed our own systems 30 years ago and have grown with the technology (just hooked up an old Trace modified sine wave at an outdoor facility we built - works great with rewired old hoxan panels, new charge controller and batteries). We had a three way call with a local electrician and finally came up with a fix. We all knew it was simply a matter of finding the right setting, but it was a journey. Since then we installed an exterior 240v female plug for the portable generator, wired to AC1, leaving the regular gen on AC2. Our next activity is headed toward local 5G...

Ernie

Dave Angelini · January 2021

Good Luck ! Winter is always the test Offgrid.
AC1/ Grid will probably only work with an inverter genset, or an extremely stable big genny that is very close to 60 hertz at XFER to XW.

Another reason to build offgrid firmware and use AC2 how an offgrid app would want.

ernievt · January 2021

I will check it out. I believe it was tested and worked with the little guy on AC1 but will get an answer and post it. Back in the day with a Trace 4024, I hooked up AC1 (before I read the manual completely) and it worked. Maybe my source was good enough. The reputation on the firmware and manual I have seen elsewhere. It seems like an easy enough improvement. Would they be open to a third party doing some or part of it - not that I am volunteering...

Dave Angelini · January 2021

I doubt Schneider would let a non-employee in on XANBUS. They do publish modbus codes for gateway and it has limits for what it can do to the system. The modbus mapping is mainly to keep LFP batts from destroying themselves from the surge ability or large solar/gensets. It allows a battery maker the ability to use its BMS to control charge/discharge current open source.

Really all Schneider needs to do is hide the grid choices in what you see for offgrid. They do not need to write anything new. This huge increase in grid choices starting with your XW+ and is off the map now with XWpro.

I believe your Trace and the ones I had needed the AC module for grid to cause problems. Without the module they were great at connecting to most gensets. Still have a few T's in the shed but would never use them as I am spoiled by modern networked power systems.

Conext XW+ 6848 trouble with the generator

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