Problem using full capacity of Seplos v4 kit v3 BMS. Firmware 1.4

[VMeldrew]

Hi.
I've recently got a Seplos v4 kit (314Ah grade A) from FogStar which I'm using with a Victron Multiplus 2 GX which I have grid connected using ESS assistant.

Assembly of the Seplos kit was interesting as no instructions were provided in the box and all that I could find online didn't quite match what I had. I contacted FogStar and they pointed me towards a video they made to show how to do it, but it was really unclear in places and again, didn't quite match what I had, but I'm reasonably confident with it.

It is basically working as expected in that it'll charge overnight and from AC coupled solar and then discharge as required, but it's not using anything like the battery capacity. I have in the back of my mind that it's possible I have something wrong when I assembled it.

It reaches 0% SOC at about 52v and gets to 99.9% at around 54v. I've not seen it at 100% SOC, despite setting up a scheduled charge session for circa 20 hours. I felt it never reaches full SOC as the current gets limited to 10A.

I feel it needs calibrating which I understand I need to do by discharging fully to say, 47v, then charging up to full, say 56v (or maybe just under). To get down to 47v, I've set the minimum SOC to 0% and I find that it discharges for quite a while at 0% (to my mind confirming the calibration being required).

To charge up to 56v is my main issue at the moment. As the charge current gets limited close to 100%, I've been using the BMSStudio to manually nudge the remaining SOC parameter to a lower figure so the current limiting is reduced, but I don't seem to get the voltage to increase much. I assume the BMS balancer is the reason, so I've setup BMS studio to data log to CSV so I can see what's happening. I've dropped this into Excel and used colour scales to help visualise what's happening, screenshots of which I've attached. Red is lower voltages and green are higher voltages for info.

To my eye, something around battery 9 looks odd. Is anyone able to tell me if what I'm seeing is normal?

Many many thanks in advance if anyone is able to help.

 

[VMeldrew]

Last minute thought. I have changed the capacity in BMS studio to match the correct Ah - forgot to mention that.

 

[houseofancients]

You haven't top balanced you cells before putting it together .
You have a cell balance issue.
The 10a charge limit at the top is there to allow for balancing to take place, and the first few time that can take hours, if you didn't top balance on forehand..

Just be patient

 

[VMeldrew]

Right. So when you say hours, as in it could be days?

 

[houseofancients]

Right. So when you say hours, as in it could be days?

Or weeks, depends how many cycles you put it through, how often you do a full charge, if you have the active balancer option

 

[Neil H]

You may have to set the batter and or inverter to allow it to drop to the low voltage state

PS I run a face book group just for Seplos battery's and have 600 members

 

[VMeldrew]

You may have to set the batter and or inverter to allow it to drop to the low voltage state

PS I run a face book group just for Seplos battery's and have 600 members

I think I have these at least approximately correct, but thank you for the suggestion. Unfortunately Mr Zuckerberg won't let me have a Facebook account, but I'll see if the wife would mind me using hers...

 

[VMeldrew]

Or weeks, depends how many cycles you put it through, how often you do a full charge, if you have the active balancer option

Many thanks for your help. I'll set it for a continuous charge for a while and monitor. Much appreciated.

 

[houseofancients]

Many thanks for your help. I'll set it for a continuous charge for a while and monitor. Much appreciated.

If you do that, make sure you always stay below the cut-off charging voltage

 

[VMeldrew]

By all means tell me I need to wait longer, but I've checked on the state in BMSStudio this morning and it's showing its in standby. 99.3% SOC, total volts 52.05v and total current 0.00A. Min cell voltage 3.251v, max cell voltage 3.261v. To me it's not doing anything.

I've switched my multiplus 2 into charge only mode via the rocker switch as I noticed despite me setting up a 24h scheduled charge (and showing as being in sched charge mode), it was showing that it was discharging.

It's showing 10 recharge cycles by the way - I've had it up and running about 2 weeks.

Thoughts?

 

[bolhuijo]

Why was the charge current getting limited to 10A? The usual reason would be cell high voltage alarm or battery high voltage alarm. What is showing up in the BMS Studio alarm area at that time?

Is the Multiplus programmed to charge up to the voltage you want?

 

[houseofancients]

Why was the charge current getting limited to 10A? The usual reason would be cell high voltage alarm or battery high voltage alarm. What is showing up in the BMS Studio alarm area at that time?

Is the Multiplus programmed to charge up to the voltage you want?

the charge is capped by the BMS as soon as an alarm pops up ( usually at 98% SOC of a cell), it does so to :

1. lighten de disconnect load on the mosfett's
2. give the balancer the time to balance out the cells ( either using the passive or active balancer)

if i take my boxes as a example, while perfectly balanced to prolongues the charge time with an hour , which is fine in my case, as my inverter will reseller the remaining solar to the grid or use it for loads..
Given the specific way victron does things, i am not sure that would work the same for OP..
that has more to do with victron's quircks than the bms.

@op , can you share the parameters in your bms ?

 

[VMeldrew]

With what you guys are saying, it sounds like there's something in the Multiplus2 config that maybe I've missed. Parameters csv from BMS studio attached (doesn't look like I can upload a CSV, so I've renamed the file extension to .txt from .csv).

Again, many thanks for your help.

 

[houseofancients]

With what you guys are saying, it sounds like there's something in the Multiplus2 config that maybe I've missed. Parameters csv from BMS studio attached (doesn't look like I can upload a CSV, so I've renamed the file extension to .txt from .csv).

Again, many thanks for your help.

2,1302,Battery high voltage recovery,54.00,V,SPA
3,1303,Battery high voltage alarm,56.00,V,SPA
4,1304,Battery over voltage recovery,54.00,V,SPA
5,1305,Battery over voltage protection,57.60,V,SPA

so your charge voltage is 57.60 and alarm ( this is when the limiter kicks in ) is at 56....
both are a bit high for my liking , but they are not the reason your bms should never hit 100% , and probably never even hits the alarm
Otherwise your bms looks fine IMHO

now, i am absolutely clueless on how a victron should be configured...
How ever, andy @ off grid garage does have the most optimum settings ( in his system ) documented , this is with comms to the Cerbo

take a peek here : https://docs.google.com/spreadsheet...31LWkNqWMgvUytVCVfMvlg/edit?pli=1&gid=0#gid=0
and look in the colum e, there's also a few video linked in that document the should give you a better idea on how to configure it somewhat good for victron

 

[dmsims]

Post some screenshots of the ESS/DVCC and BMS settings from Venus

 

[bolhuijo]

I'm wondering if the charger settings in VEConfig for the MultiPlus have proper settings?
example:

 

[dmsims]

The battery settings in the Multiplus are not normally used in an ESS system , they are provided by the BMS

 

[dmsims]

OP what does you parameters page show under the BMS device

e.g.

 

[VMeldrew]

Requested screenshots attached. Thanks again guys.

 

[dmsims]

3.6V per cell is too high (IMHO) - You might be triggering OVP a lot!

I would aim for 3.45V per cell

Just change it in the BMS

 

[houseofancients]

3.6V per cell is too high (IMHO) - You might be triggering OVP a lot!

I would aim for 3.45V per cell

Just change it in the BMS

3.45 is too low, if that is a bms with a passive balancer... 56 ( 3.5 ) or 56.8 ( 3.55) would be better

 

[dmsims]

I have zero issues with 3.45V and a passive balancer - there is nothing to be gained going over 3.45V

 

[houseofancients]

I have zero issues with 3.45V and a passive balancer - there is nothing to be gained going over 3.45V

it's not about gaining any AH, it does have to do with the cell diffs and the knee that only starts at 3.48 , before that , balancing is rather pointless and when using a passive balancer a waste of power

 

[dmsims]

Well that BMS sets 100% SOC at 3.45v and you are going to trigger a whole load of warnings as well

 

[bolhuijo]

The battery settings in the Multiplus are not normally used in an ESS system , they are provided by the BMS

edited! BMS parameter 102 "Charging request voltage" is used by the MPPT (only when DVCC is engaged I think)