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Seplos BMS



  • Registered Users Posts: 1,856 ✭✭✭garo

    Can you take a screenshot of the individual battery voltages? I can see the min and max and cannot imagine why the BMS would think the battery is at 10%. Did you charge to 100% and then discharge to shutoff to let the BMS learn capacity? If not, you may want to do that. In the current state, I would just manually up the SOC to 80% and let the battery discharge.

  • Registered Users Posts: 5,750 ✭✭✭championc

    @E30M3 Did you get the 10% when you first turned on ? If so, the first "switch on" SOC% can be haywire. The Seplos needs at least one full charge and discharge cycle to 'learn" your battery capacity.

    So hopefully you told it to charge to 100% overnight last night. If you were graphing your SOC%, it quite likely jumped from about 30% directly to 100%.

    You will also need to go through several cycles for your cell voltages to narrow. There's a huge gap between your highest and lowest.

  • Registered Users Posts: 791 ✭✭✭reklamos

    The battery SOC deos not look right in first picture. Voltage 51.63V is too low for 100% SOC. Have you done full charge/discharge cycle at 0.5C?

  • Registered Users Posts: 301 ✭✭E30M3

    What is the best way to do this at .5C? I had a look at the parameters but wasn't sure what to change to achieve this. Tks a million all.

  • Registered Users Posts: 5,750 ✭✭✭championc

    These cells will do 2c and higher I think. I think some people are overthinking this saving craic

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  • Registered Users Posts: 73 ✭✭puntypower

    What's the difference between a seplos BMS and other BMS you can get on Aliexpress?

  • Registered Users Posts: 5,750 ✭✭✭championc

    The Seplos appears to be the only one which can be connected directly to the inverter, by emulating (fooling the inverter into thinking) a connected Pylontech pack.

    The AliExpress ones are standalone and the inverter then has to "guess" what the SOC% is constantly.

  • Registered Users Posts: 791 ✭✭✭reklamos

    use timed charging/discharging and set amps in there.

    Sure they can do, I am just quoting what Seplos recommends doing to aquire proper SOC.

  • Registered Users Posts: 791 ✭✭✭reklamos

    Got my second pack connected today. Have now 2 batteries in parallel 1x master and 1x slave. The pack do communicate to each other and also balance out to keep the same voltage on both packs. The master is providing total SOC to Solis. My slave pack has not figured out its SOC correctly yet so even though both pack are at same voltage the SOC is different. Hopefully couple cycles will even them out.

    On thing that does not work though is software. It can only see salve pack but not master. According to Seplos this is expected as you can have either PC connected or inverter which does not sound right to me. Anyway will keep on testing.

  • Registered Users Posts: 1,894 ✭✭✭SD_DRACULA

    I assume you have connected one seplos BMS to each pack? 16 cells per pack?

    Interesting stuff especially for adding on cells at a later stage.

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  • Registered Users Posts: 421 ✭✭Geeyfds53573

    On this clip you can see the software flicking through the 4 packs this guy has. It that not what you should be seeing?

  • Registered Users Posts: 791 ✭✭✭reklamos

    I seen this video. To be able to flick through he needed to change master pack id from 00 to 04 but then it is no longer a master pack.

  • Registered Users Posts: 14 Puitl

    Has anyone the same problems like I have? Wrote this to Victron Energy in the Victron-Forum:

    Everything works fine but before i write a short review here i have a questions, a issue and a problem:


    Seplos says they are sending the voltage of every single cell to the inverter but in the Controlpanel i can´t see them!?

    I guess this feature need´s programming on your side?

    Can you show them into the Panel?


    The DVCC-Function "Max. charge-voltage" works perfectly but the function "Max. charge-current" does only act when charging from the Multiplus.

    When charging from the MPPT´s this function does nothing.

    According to the desccription in the Cerbo-GX manual this function should control the max. charge-current from all inverter/chargers AND all MPPT´s.

    Whats wrong here?


    The Seplos sends a max. charge current limit (CCL) of 10A when a cell exceeds 3,5V.

    In the attached picture you can see that the Systems recognize this but doesn´t react:

    CCL is set on 10A but the ESS is charging with full power from the MPPT´s until the BMS cuts of.

    Also: Whats wrong here? Is it a software problem or do i only have to adjust a setting?

    (I guess Problem 2) and 3) have the same "root"...)

  • Registered Users Posts: 47 optip

    Not sure if this is helpful - but I have a Victron system with BYD CAN battery that behaves correctly when charging from MPPT. (kinda similar to what you're shooting for)

    below are my settings for the MPPT / Networked Operation settings - can you check if yours are similar? especially the 'Mode Setting' of 'Ext. Control & BMS'. This requires a cable from the Venus device to the MPPT to work - I can't tell from your VRM screenshot if the MPPT is detected (& sorry if that's overly basic troubleshooting! 😀)

    I'll be upgrading to a Seplos BMS based battery in the coming months - I very much hope the victron-seplos combo behaves for you :)

  • Registered Users Posts: 14 Puitl


    My settings in this menu are exactly the same as yours!

    What is very strange:

    When i set CVL (in DVCC-menu) to 55V or 54V, the "charge voltage" of the MPPT goes down to 55,4V / 54,4V (in MPPT / Networked Operation settings).

    (0,4V higher because of cable-voltage-lost i think....wherever i can set these value because i noticed that 0,2V will be more appropriate at my system)

    -> So CVL does act in the MPPTs but only CCL does not

    I have no idea why and on Victron Forum (Victron community) i don´t get an answer...

  • Registered Users Posts: 14 Puitl

    With pulling up the following thread i get to the answer why it doesn´t work:

    (Can´t post links here, just search on google for:

    "BUG in ESS - DC Feed-in enabled, Charge Current Limit (CCL) from BMS ignored"

    Short summary:

    Victron cannot reduce the charge current when charging from the solar chargers because of the risk of destabalize the system.

    They recommend to reduce the end of charge-voltage (CVL) when single cell-voltages are getting to high.

    @optip Does your BYD really reducing the CCL and you can watch this in MPPT / Networked Operation settings or does it mybe also reduce the CVL?

  • Registered Users Posts: 47 optip

    my battery is around 100% currently, filled by the MPPT/sushine... here is a screenshot of my parameters while at 100% soc

    when the battery gets full, the MPPT continues to generate power - but the inverter sends it to the grid rather than letting it go to the battery.

    I haven't been able to see a limit reflected in the MPPT itself similar to the CCL, but controlled by the GX.

    A fallback option I am considering for myself is to use basic voltage settings to configure the battery rather than CAN connection. Might be useful while troubleshooting the CAN connection. Longer term I'm hoping to use CAN to control low temp charging properly.

  • Registered Users Posts: 14 Puitl

    Haha 🤪 strange strange strange

    and reducing max. charge current in the DVCC-menu while MPPT´s are loading the battery with full power does also work at your byd-system?

  • Registered Users Posts: 47 optip

    I currently have a manual 60A DVCC limit configured because my baseload went down leaving too much solar excess for my (small) battery. Without that limit, my battery throws alerts relating to over-current.

    I'll set it to 20A tomorrow (assuming sunshine) to confirm it works properly - i.e. that the MPPT adjusts it power to baseload + 20A for the battery

  • Registered Users Posts: 14 Puitl

    Yes pleace test it because in the victron-thread i asked yesterday why this works with your BYD and i get following answer:

    "the Victron system works the same with BYD, BYD lowers CVL when battery full. But if you take a small BYD battery and big MPPT's, combined with too little feed-in capacity, it will also charge more current than asked."

    When you turn it down to 20A please look into the MPPT / Networked Operation settings and have a look: The MPPT charge-current must then also be lower here.

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  • Registered Users Posts: 47 optip

    test complete

    while the sun was shining and charging the battery with 30A+, I set the DVCC limit to 10A. This had no effect - the MPPT kept charging at full speed until the battery approached 100% and then the mppt dialled back the power.

    I suspect that setting will affect the Multiplus charging the battery from grid - I can test that tonight if that's helpful.

  • Registered Users Posts: 47 optip

    "When you turn it down to 20A please look into the MPPT / Networked Operation settings and have a look: The MPPT charge-current must then also be lower here."

    Sorry - I didn't specifically check this and now my battery is 100% so I can't check again until a good cloud comes through.

  • Registered Users Posts: 14 Puitl

    Then tomorrow after this discharging-night when the sun powers down ☺️

  • Registered Users Posts: 47 optip

    the sun hid for long enough for the test :)

    this parameters screen seems to ignore the 10A limit set under DVCC

  • Registered Users Posts: 14 Puitl

    Ok then it´s the same at your system, everthing else would be strange^^

    BMS-CCL and "Max. charge current" has no or almost no influence on the System (only when charging from grid with the Multiplus) because it is technically not possible to reduce charge-current when there is PV-power comming in and CVL has not be reached.

    The only way to reduce charge-current is to set down CVL - your BYD seems to do it, the Seplos do it not (maybe with an update because i wrote them that it makes sense 😁)

  • Registered Users Posts: 47 optip

    sorry I couldn't be more help!

    please let me know how you get on with this... I already have a Seplos BMS with cells still in transit. Seems likely I'll have a similar issue to yourself.

  • Registered Users Posts: 14 Puitl

    You helped a lot!

    One thing that would be nice to know if the BYD-battery really reduces CVL when for example on cell gets over a voltage-limit, but then you have to disbalance one cell 😅

    For me it is no problem when this safety-feature don´t work with the seplos because I only charge up to 55,2V (3,45V per cell) - so I protect my battery and I will skip the last few Ah of the capacity.

    Once or twice a year I will charge the battery full and then slowly go up with the voltage to 3,55V or 3,60V per cell to do a clean top-balance and "update" the real SOC

  • Registered Users Posts: 3,059 ✭✭✭irishchris

  • Registered Users Posts: 73 ✭✭puntypower

    Where is the best place to buy one of these now? Just about to pull the trigger and buy batteries from oye too.

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