BMS for Schneider Conext

I assume you have the 4.2V cells since you're doing 14S. It's usually best to parallel first, then series when you build your battery - make one big battery then all you need is a 14S BMS. You'll want to make sure they are all equalized. What I did with mine was to parallel all 64 cells and charged them to 3.5-ish (I have LiFePO4 chemistry) using my bench power supply (you can buy one on Amazon for not a lot of $$, just make sure you get one that can do 10A or it will take 2-3x longer to get them topped off.) Then I let them rest until the voltage settled and to make sure they balanced each other. Then I built my battery as a 4P16S (LiFePO4.) I also made my own bus bars from copper bar stock. I've attached a Sketchup drawing of how mine are setup. I used 2x8 blocking at the ends and 4 rods of all-thread to compress them. I bought some clear tubing to encase the all-thread rod into for safety. The hardest-longest part was building the bus bars. I wanted as few connections as possible to minimize voltage drop across the whole battery.

Like I said about the Schneider BattMon - I derated the Ah total for mine from 1088Ah rated down to 980Ah and (so far) I haven't seen them drop below 70% as tallied by the BattMon/Shunt. I expect these to last me at least a decade. I have my CC set to 56V Bulk, 54.6 Absorb for 45 mins (though I'm thinking of extending this - I've been extending it as I go and watching the Balancer. The cells never really get past 15mV out of balance. I have Float set to 54V. You can adjust accordingly for your chemistry.

I should have mentioned, you can check out how my system is setup on my YouTube channel: JC/DC in the AZ https://www.youtube.com/channel/UC8_TU2g-Yl1oMCts3pkXCbQ

I'm going to be posting a new video soon with my battery upgrade stuff. We live 100% off-grid, so lots of cool stuff going on.

OK gang! I finally have a working prototype for the software component. I finally figured out how to convert ModBus values to ASCII so I can view real values. I've setup a server to provide API access to (today) specific aspects of my Scheider setup over ModBusTCP. The fields I currently have access to: Name, SOC, Voltage Capacity, State, Status, Load, Faults, Warnings, PV Power, DC Power. Basically, I can get any information I want now via the Conext Gateway. I can even send commands like: switch CC to Float or put the Inverter in StdBy. I've linked my API to my installation of Home Assistant. I'm able to display all the aspects above on my HA dashboard - really cool!

If you haven't seen Home Assistant, it's pretty nice. I have a lot of my house setup to use it like lights, H2O heater, Temp sensors and now Scheider!

I've looked over a lot of different hardware for monitoring the cells. I haven't decided yet on what I want to use:
ModBus Balancer/Cell Monitor (can get these on eBay)
DIY BMS (there are few out there, but Stuart Pitaway is the leader for these)
GWL CPM board (Comes from EU, so shipping takes some time and support will lag a day or two)

I think the cheapest option is the Balancer. I have one now (2A balancer/24 cells) that is popular on YouTube, but it only does BLE and I couldn't hack this one. So I'm looking at the CAN/ModBus model. Both you can get on eBay. You don't have to turn on the Balancer, but I haven't found any adversity using it and lots of people on YT are using that way.

FYI: here is a screen shot of my Solar Dashboard in Home Assistant.

That is awesome news!

I need to research more and dig (after I complete the install and pass inspection), but I would be very interested to see more if you are willing to share on GitHub or something.

shorawitz said:

Basically, I can get any information I want now via the Conext Gateway. I can even send commands like: switch CC to Float or put the Inverter in StdBy.

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You probably know this but others may not.

NEVER put the inverter in standby unless you have a ComBox externally powered. It will brick the system. The Gateway may not have this issue.

I learned this the hard way:

JoeHam said:

You probably know this but others may not.

NEVER put the inverter in standby unless you have a ComBox externally powered. It will brick the system. The Gateway may not have this issue.

I learned this the hard way:

HELP! Schneider Conext SW and ComBox

So I got my SW 4048 up and running with my critical loads panel connected. Worked fine. Then I hooked up the ComBox and established communications with the Conext SW. While testing the communications I hit the standby tab. I now know that this immediately shuts down the entire system, which...

diysolarforum.com

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Interesting. I wonder if this applies to also having an SCP. I just looked at my SCP and it does have an option for StdBy. Did you find any docs that say not to do this w/o a Combox or Gateway?

400bird said:

That is awesome news!

I need to research more and dig (after I complete the install and pass inspection), but I would be very interested to see more if you are willing to share on GitHub or something.

Click to expand...

No problem. I created a video on my YT channel where I demonstrated my setup w/Home Assistant:

And I did publish the code on Github. If there's interest, I could publish another video going into more details on getting this seutp.

shorawitz said:

Interesting. I wonder if this applies to also having an SCP. I just looked at my SCP and it does have an option for StdBy. Did you find any docs that say not to do this w/o a Combox or Gateway?

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It’s somewhere in the 125 page manual which was not provided with my CSW4048 as noted in my HELP thread post mortem note.

I don’t believe this is an issue with the SCP but I don’t have one so no experience there.

JoeHam said:

It’s somewhere in the 125 page manual which was not provided with my CSW4048 as noted in my HELP thread post mortem note.

I don’t believe this is an issue with the SCP but I don’t have one so no experience there.

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With XW, you only brick your system when you perform an inverter firmware update without alternate power to the combox/gateway. IIRC the firmware readme warns about this. You should be able to put the system into standby via the combox/gateway/scp without any problem as long as you are not doing a inverter firmware update. Maybe there is something weird with the SW units.

IMO, the SW inverters are crap. Years ago I bought two of them to use synchronized. They kept frying when the generator came on. There is/was some bug that causes one inverter to feed the other in some weird current loop. As stand alone units they worked fine for me, but I've heard of other problems with single units and generator use. I went through 6 of those SW inverters working with Schneider support. They identified a bug in the inverters and tried to fix it and gave me new beta firmware, but it didn't work. After going through all those SW inverters, they eventually gave me two XW4024 units with pdp and all the stuff required for putting then in parallel. I didn't have a problem with the XWs for ~10 years until I went to replace my battery. They no longer sync, but work fine as standalones. The problem is they read different dc voltages. There is a tool to calibrate this but it's $600 and I was moving to 48v anyway. Now I have a XW6848 pro which was a drop in replacement since it works with the same pdp, etc. The XWs are solid units, SW not so much.

jtvt said:

With XW, you only brick your system when you perform an inverter firmware update without alternate power to the combox/gateway. IIRC the firmware readme warns about this. You should be able to put the system into standby via the combox/gateway/scp without any problem as long as you are not doing a inverter firmware update. Maybe there is something weird with the SW units.

IMO, the SW inverters are crap. Years ago I bought two of them to use synchronized. They kept frying when the generator came on. There is/was some bug that causes one inverter to feed the other in some weird current loop. As stand alone units they worked fine for me, but I've heard of other problems with single units and generator use. I went through 6 of those SW inverters working with Schneider support. They identified a bug in the inverters and tried to fix it and gave me new beta firmware, but it didn't work. After going through all those SW inverters, they eventually gave me two XW4024 units with pdp and all the stuff required for putting then in parallel. I didn't have a problem with the XWs for ~10 years until I went to replace my battery. They no longer sync, but work fine as standalones. The problem is they read different dc voltages. There is a tool to calibrate this but it's $600 and I was moving to 48v anyway. Now I have a XW6848 pro which was a drop in replacement since it works with the same pdp, etc. The XWs are solid units, SW not so much.

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I have the SW4048 installed in 2018 and it has been rock solid.
What year SWs did you have problems with?
They seem to have address the problems as I haven't heard of current complaints.

LR~Eagle said:

I have the SW4048 installed in 2018 and it has been rock solid.
What year SWs did you have problems with?
They seem to have address the problems as I haven't heard of current complaints.

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That's around 2014. I think there is something inherent with their design that is the problem. I've heard of newer ones having similar problems. Mostly in parallel, but not always.

shorawitz said:

Interesting. I wonder if this applies to also having an SCP. I just looked at my SCP and it does have an option for StdBy. Did you find any docs that say not to do this w/o a Combox or Gateway?

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I have a CSW4024 and the SCP. No Combox or Gateway in my system. Our standard procedures are to put the Inverter in standby (via the button on the SCP) whenever someone departs from a visit to the cabin. When someone makes a new visit to the cabin, they take the inverter out of standby via the same button. This has worked fine for 4 years.

I've updated the API to now display the correct temperature of the batteries if you have a probe plugged into your system. It took me a while to figure out how they are calculating the value and Schneider support didn't even have the answer. I happened across it in the latest BatMon manual that has a section for Modbus and the calculation is listed there.

Here's my Github repo:

Here's my YouTube channel where I talk about all things solar and off-grid:

Here's a new screen shot of my Home Assistant Solar dashboard. I have a temperature sensor in the room next to the inverter (bottom left graph) and a Wifi connected A/C (bottom right) show it's current temp and setting that I can adjust as needed from HA using my cell phone:

400bird said:

I am looking to add a Schneider Conext XW pro for battery storage to my existing solar.

Currently I have a 6kw Solar Edge inverter.
I installed this system myself along with the 20 panels on the roof and the critical loads panel.

I suppose I am not stuck on the Schneider, but it is rated to provide enough current to start and run my AC.


The question I have, does anyone know what BMS's can communicate on the RS485 the Conext gateway provides for the battery? I can't find any that do. There is some old literature that the 48v LG resu would work. But I think that LG discontinued that battery?

Thanks in advance!

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I‘m about to purchase a solaredge grid tie inverter. I’m considering getting a used Schneider hybrid CONEXT 4048. Do you know if these two inverters can be ac coupled?

I've never read anything on the 4048 (it would be better if you include the entire model number) so I don't know anything about it.

The solar edge inverter will have multiple grid profiles, so you need to choose the correct one for regulations in your area, and read about that selection.

You'll need to look at the manuals for each inverter to inverter to see if they work with frequency shifting to curtail PV production.

Anit767 said:

I‘m about to purchase a solaredge grid tie inverter. I’m considering getting a used Schneider hybrid CONEXT 4048. Do you know if these two inverters can be ac coupled?

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The SW4048 (like the SW4024) does AC coupling - provided you have updated firmware (something to think about if you are buying a used one). Updating the firmware is a precise process and requires either a Combox, Gateway or System Control Panel. Read up on it first.
My SW4024 is AC coupled with M-215 micro inverters (an older Enphase generation). The M-215s only know how to cut off and on (slam bang) according to frequency. More modern inverters have a gradual taper - you would have to check with Solaredge to be sure of that feature/capability.
In all cases, your battery should be sized to take the full output capacity of the AC inverter/s - generous headroom is well advised. Best.

GVSolar said:

The SW4048 (like the SW4024) does AC coupling - provided you have updated firmware (something to think about if you are buying a used one). Updating the firmware is a precise process and requires either a Combox, Gateway or System Control Panel. Read up on it first.
My SW4024 is AC coupled with M-215 micro inverters (an older Enphase generation). The M-215s only know how to cut off and on (slam bang) according to frequency. More modern inverters have a gradual taper - you would have to check with Solaredge to be sure of that feature/capability.
In all cases, your battery should be sized to take the full output capacity of the AC inverter/s - generous headroom is well advised. Best.

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Thanks for the detailed response.

Hello all,

Old thread but looking for help. I have 2 Schneider XWs with a bank of lead acids I need to replace. I'm just begining this DIY LifePo4 process, built a 12 pack for another system as a means to educate myself. Now I'm preparing to go big and build 2 16S packs, maybe a total of 6 down the road. It would seem I have some problems ahead of me regarding Schneider and my BMS talking nicely to each other. The desire was to have a Batrium BMS. I can configure the XW's via LVBCO and AGS Triggers, but...

1- Not real accruate, right? Just voltage?
2- Does anyone have problems with inaccruate DC voltage displayed on the MCP? My voltage has always been off. I wing-it with my LA bank. The disparity changes from .3-.6 volts. I'm worried I can't even use voltage as triggers as they are inaccurage. I need to be preceise to not kill the batteries- or burn down my house.
3- The desire would be to have the BMS (Batrium???) send a trigger to stop inverting or stop charging. Period.

Thanks,
James

For #2, yes my voltage reading always has a similar error.
Supposedly the Schneider battery monitor is recommended to address this.

I have verified the most basic BMS communication between my Batrium and XW. I've sort of dropped the ball, but Batrium seemed interested in getting the verification that it worked.

Edit: I hit save on accident, oh well...

I'm out of town for the week, but I need to get back to this once I'm back. Could take a couple weeks, but I'm confident it will work with what little I've seen so far.

400bird said:

For #2, yes my voltage reading always has a similar error.
Supposedly the Schneider battery monitor is recommended to address this.

I have verified the most basic BMS communication between my Batrium and XW. I've sort of dropped the ball, but Batrium seemed interested in getting the verification that it worked.

Edit: I hit save on accident, oh well...

I'm out of town for the week, but I need to get back to this once I'm back. Could take a couple weeks, but I'm confident it will work with what little I've seen so far.

Click to expand...

I have the Scheider BMS on my Lead Acid Batteries. I may not be using it to it's full potential, I need to explore that idea. On my system right now, I use Voltage Triggers to activate the Generator. This set up won't work with the LifePo4 upgrade. Without exploring the Scheider Battery Monitor, the triggers are based upon what I see on the SCP- those #'s are off. I Kentucky windage the voltage. It doesn't work very well with the voltage diparity changing often.

Can I ask what communication you have with your Batrium? How successful have you been?

Jbbonnette said:

I have the Scheider BMS on my Lead Acid Batteries. I may not be using it to it's full potential, I need to explore that idea. On my system right now, I use Voltage Triggers to activate the Generator. This set up won't work with the LifePo4 upgrade. Without exploring the Scheider Battery Monitor, the triggers are based upon what I see on the SCP- those #'s are off. I Kentucky windage the voltage. It doesn't work very well with the voltage diparity changing often.

Can I ask what communication you have with your Batrium? How successful have you been?

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I don't have the battery monitor, so I can't speak to it working or not.

I wired the CAN lines from the Batrium to Schneider In Site Home, the Schneider could see SOC, that's as far as I made it

Also, you may have access to more settings using the web interface than the SCP. I'm not sure

400bird said:

I don't have the battery monitor, so I can't speak to it working or not.

I wired the CAN lines from the Batrium to Schneider In Site Home, the Schneider could see SOC, that's as far as I made it

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Gotcha. Thanks for the information.

I will say, the voltage on the Scheider Battery Monitor is the same incorrect voltage on the SCP- I just looked. I do find this shocking. It's wired right up to the bank... How on earth could it be wrong, and the "same wrong" as the SCP.

Weird.

I sure like Batrium, but I'm on a lead the the Orion Jr. 2 can be "bootlegged" to work. Another very helpful forum user has his shutting off inverting and charging with signals from the BMS.

I have the battery monitor and Batrium. I don't have any integration. The last I heard it was a work in progress. One thing i've noticed is the SOC from the batrium tends to be wrong.