Grid feed in stopped working after BMS changed from Batrium to Seplos

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question

thekwchallenge asked Mar 11, '24

Grid feed in stopped working after BMS changed from Batrium to Seplos

Hi all,

My Setup:

3 x Multiplus II 5000/70 in 3 phase configuration

1 x 450/100 MPPT Charger

1 x 450/200 MPPT Charger

1 x Cerbo GX

1 x Victron EVCS Car Charger

30kwh LiFePo with Seplox v3 BMS

For the past year I've been using this setup but with a Batirum BMS, everything has worked perfectly regarding charging batteries, cars, and feed in / exporting. With the Batrium BMS, the Victron equipment would charge the battery first, then when with battery was 100% SOC it would divert the excess energy to the car charger if the car was plugged in. When the car was full, or if is wasn't connected, the equipment would then direct the excess power to the grid as expected, everything worked a treat.

Now that I have changed to a Seplos BMS, everything works as before but the system no longer exports to the grid! The system will charge the battery to 100% SOC, then divert the excess energy to the car charger as normal but will not automatically export to the grid as before when the car if full or not connected! The system simply reduces the solar production to match the load!

Nothing has changed in the config from before and yes, if I set the grid set point to -1000 for example, it will sit there all day at -1000 so I know it "can" export as it did before.

I know that CCL is ignored when feed in is enabled in ESS (how long have we been asking for that to be fixed!) but I suspect when the battery is full and is in turn, set to zero, there's something different with how the Batrium and Seplos BMS's tell the GX device to stop charging the battery.

Does anyone out there have Seplos v3 BMS and is able to export? Anybody at all?

Does anyone have any ideas as to why changing the BMS has stopped my grid feed in from working? Happy to share my settings but please remember, I've been exporting successfully for a year, only the BMS has changed.

Thanks all and with cap in hand :-)

Darren

ESS feed-in seplos

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Modifications Space

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Answer 1 · 2024-03-11T16:04:26Z

nickdb answered · Mar 11 at 04:04 PM

Did you change the battery monitor to point to the new bms in the gx system setup?

And to double check it has been correctly detected in dvcc.

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Answer 2 · 2024-03-11T17:08:58Z

thekwchallenge answered · Mar 11 at 05:08 PM

Yeah I did.

System Setup -> Battery monutor: Seplos BMS
System Setup -> Battery Measurements: Seplos BMS Visible

Here's my DVCC settings:

(The temperature sensor name is correct, that's in the Seplos BMS)

Heres my ESS settings:

Grid Feed in settings:

As you can see, the Seplos BMS is reporting fine over the CANBUS:

Its getting dark now thats why CCL is at 280 but when the battery is full, obvioulsy it drops to 0. The CVL stays at 55.2v all the time, it never changes.

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Answer 3 · 2024-03-12T09:32:53Z

thekwchallenge answered · Mar 12 at 09:32 AM

Can anyone from Victron assist me with this?

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nickdb ♦♦ commented · Mar 12 at 09:37 AM

Unfortunately, on unsupported BMS's there is little support. Best is search here for topics containing SEPLOS, maybe you can @ another member who uses it.

The community is also not for support requests, it is mainly for knowledge sharing.

Were any other (settings) changes made anywhere that didn't also apply to the previous bms?

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thekwchallenge nickdb ♦♦ commented · Mar 12 at 11:16 AM

Thanks for your reply Nick! No I literaly turned off the system on Friday, took out the Batrium BMS, installed the Seplos, using the same CAN bus settings and port and on the Monday when I turned the system on, I could see as soon as the battery was full, the feed in was not working. What's really strange is that the system knows the battery is full and there's excess energy because it still turns on the car charger when the battery reaches 100% SOC and it diverts the excess to the charger as normal. I'm beginning to think theres something being sent over the CAN bus, something other than CVL/CCL/DCL which is stopping Victron inverters from exporting to the grid. Maybe Batrium changes the CVL during charging, or when it reaches 100% for example...

I've reached out to Seplos for assistance as well, no response as yet.

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Answer 4 · 2024-03-12T10:38:23Z

nickdb answered · Mar 12 at 10:38 AM

@thekwchallenge Try disable SVS in DVCC and indeed the STS, the BMS should be sending what the system needs via CAN anyway.

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thekwchallenge commented · Mar 12 at 11:21 AM

Ok thanks, I will try that, it's cloudy today so I'll charge from the grid in the night and give it a go tomorrow.

Ive been reading about the 0.4v voltage increase DVCC applys during feed in, maybe this problem is related to CVL? At the moment, everything is set to 55.2v, the chargers, DVCC and the BMS everything, as it was before with Batrium but like I hinted in my last post, maybe Batiurm changes the CVL during the charging cycle or when it's fully charged? If I had another house with the same system, and 16 more cells to reinstall the Batrium, I could test that :-)

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Answer 5 · 2024-03-12T14:07:37Z

prein answered · Mar 12 at 02:07 PM

Possibly ccl is set to zero when Te battery is full, disabling the mppts.

That can be solved by setting the over voltage warning parameter in the seplos bms a bit higher. (For instance 56V), while keeping the override in the cerbo in place. That way the bms doesn't go in a warning state and doesn't reduce ccl

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thekwchallenge commented · Mar 13 at 12:39 PM

Thanks for your answer Prein, I don't think it this will be related as I beleive CCL is ignored when ESS is active and DC feed in is enabled:

From the manual:

Note: When DC-coupled PV feed-in excess is enabled with ESS, the DVCC system will not apply the DVCC charge current limit from PV to battery. This behaviour is necessary to allow the export. Charge voltage limits will still apply.

Are you running a Seplos BMS? Would be good to compare settings

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nickdb ♦♦ thekwchallenge commented · Mar 13 at 12:44 PM

This is a misconception, it will only ignore the user set parameter in DVCC.

In other words, your 200A manual limit.

Without export enabled, the system would honour whichever is the lowest of CCL and the manual limit.

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prein thekwchallenge commented · Mar 13 at 06:56 PM

I am running a seplos v2 bms. So quite comparable, not fully..

Please check the ccl value of the bms when you experience issues. I do think it is related, although the manual states otherwise..

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Answer 6 · 2024-03-18T15:19:26Z

thekwchallenge answered · Mar 18 at 03:19 PM

Thanks for all the suggestions and tips everyone, I'm happy to report it's now working as it should.

For the benefit of anyone else having a problem whereby they can't get feed in to work from DC when running ESS and DVCC, especially with a Seplos v3 BMS here's how you need to configure everything (for a 48v LiFepo system) to get it working correctly:

1. In the Seplos BMS settings, set the Requested Charge Voltage / CVL / Max Charge Voltage to 55.2v (thats 3.45v per cell)

2. In DVCC set the Maximum Charge Voltage to 55.6v. This delta of 0.4v gives the system the extra voltage to faciliate exporting. Make sure "SVS - Shared Voltage Sense" is turned OFF in the DVCC settings as well.

3. Remember when running ESS in your inverters, the CCL coming from the BMS is ignored so you MUST set the Max Charge Current in your solar chargers instead.

That should be enough to get you going and then you can tune the settings to your own needs from that point.

Now, in my setup, the Victron equipment charges the batteries in the house first, then charges the car if it's connected, after all that, it will automatically export until there is no longer an excess of energy, exatly as it was with the Batrium BMS.

Screenshots of my settings in case it helps anyone:

Seplos BMS -> Parameters (battery 100% charged at time of picture):

Settings -> DVCC:

Settings -> ESS:

Settings -> ESS -> Grid Feed-in:

The final result:

Good luck everyone and thanks again.

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nickdb ♦♦ commented · Mar 18 at 03:25 PM

Some of that does not compute.

Setting a DVCC max CVL ABOVE the BMS CVL will be ignored. The lowest is honoured.

That setting is for LOWERING the CVL from the BMS to aid balancing, it is incapable of raising it.

The 0.4V is implicit in the DVCC code when you enable exporting and some other ESS features.

Likewise, as already discussed, DVCC will always try honour the CCL, and all things being equal on a well configured battery, it should work just fine, only manual limits are lost.

Clamping charge at the MPPT level restricts all production for loads through to exporting and ultimately won't affect whether or not power decides to go to the battery.

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thekwchallenge nickdb ♦♦ commented · Mar 19 at 04:42 PM

A lot of it doesn't compute, that's why I reached our for help :-)

Still, I've posted my "before" and "after" settings to help the next person with the same problem.

Thanks again for your comments, really interesting chat.. In reply...

Setting a DVCC max CVL ABOVE the BMS CVL will be ignored. The lowest is honoured.

Yes I think you're right, I agree with you but in my testing, DVCC CVL became one of the variables I found to affect the exporting. I can do more testing with it when the sun eventually comes back to Sweden! Would be interesting to see what happens if, now that it's working, I change that back to 55.2v, I'll try that and report back.

The 0.4V is implicit in the DVCC code when you enable exporting and some other ESS features.

I've also read this deep in the manuals and I agree with you but it was a few people discussing enforcing this delta in the 2 CVLs by setting them to different values to trigger the exporting. It was those posts which broke the ice for me and opened up the route to finding the solutnion.

Likewise, as already discussed, DVCC will always try honour the CCL

Unless I am missunderstanding what you're saying, this one I disagree with. In my system here, with ESS, DC grid feed in and DVCC all turned on, with a Victron charging station on the external AC side, it doesn't matter what CCL your BMS sends when grid feed in is turned on and you're charging, it's ignored, only CVL from the BMS seems to be honoured and is the principal metric to control charging. That frightnend the life out of me when I first saw it and quite a few people have posted about this raising concerns. Doesn't affect me as my system is well spec'd but I included that comment to help people who dont know this because it's dangerous, hence my comment regarding CCL in the chargers.

For the benefit of the group, and for everyones understanding, is there anything you would like me try and change in the settings to see if it affects the resolution? The first thing I'll do is bring down the DVCC CVL to the same as the BMS CVL (55.2v) to see if that's not related, anything else?

Sooooooo, happy to finally be exporting again!

Cheers all

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