Seplos BMS

slave1

Read about that alright, no idea

randombar

Hi All,

Just wondering what is good battery performance vs what are batteries that require rebalancing.

https://www.dropbox.com/s/8mgw28unjhcp34b/Screenshot%202023-01-08%20at%2010.28.06.png?dl=0

Maybe 0.02v between max and min at the moment.

unkel

Hard to say, right in the flat curve. Charge them up fully to 3.65V each and then check what the differences are. If you have cells that go shoot up way before the others, you have imbalance. What's likely though is that one cells hits 3.65V or whatever threshold you have set and the BMS stops further charging. Making you think all is hunky dory, but you're losing out on capacity and you have an imbalanced pack

Always the danger about using BMS. You might have protection, but it gives you a false sense of security that all is well

graememk

https://www.boards.ie/discussion/comment/120081101#Comment_120081101

Imbalance only shows up just before charge completion, as they will settle back to 3.3x after a while.

If you are getting all cells above 3.5 its pretty well balanced.

randombar

https://www.boards.ie/discussion/comment/120081733#Comment_120081733

I think it looks ok but I'll keep an eye on it.

https://capture.dropbox.com/jFyvHv4jvDKLkQLz

unkel

https://www.boards.ie/discussion/comment/120081786#Comment_120081786

Depends, one is only at 3.39V when some are at or near 3.65V. Not a well balanced pack. Either live with the reduced capacity, take them apart and parallel them, install an active balancer or replace the Seplos with a BMS that can do active balancing

I think @graememk has a nice rule of thumb there. If you can get all of them to about 3.5V, that's as good as you need them to be

slave1

Can you top balance and then put onto the Seplos, they may drift after a while but at least you know you are starting off in a correct manner

randombar

The thought of having to take them all apart to parallel them and top balance gives me the chills.

any recommendations for a Bms that does the active balancing?

is Seplos losing its shine?

(as soon as I get it installed into ha 😂)

randombar

I thought I did top balance before install tbh

unkel

@randombar - "The thought of having to take them all apart to parallel them and top balance gives me the chills."

Do it 15-20 more times and you will be able to go from series to parallel in no more than 15 minutes, trust me😁

@randombar - "I thought I did top balance before install tbh"

I'm sure you did, but if you don't use a device that can balance them, they will inevitably drift apart over time

unkel

Andreas giving out stink about Seplos BMS

https://www.youtube.com/watch?v=liu86NoFiQc

tl;dr only a problem if you have two battery packs and neither of the Seplos has bluetooth. But the bluetooth doesn't seem to be functioning well either

randombar

https://www.boards.ie/discussion/comment/120083405#Comment_120083405

So that Neey yoke will save me all that hassle?

unkel

https://www.boards.ie/discussion/comment/120083570#Comment_120083570

No.

We're all between a rock and a hard place. If you want a very good and good value BMS, with bluetooth, app, and active balancing, and also a very easy to understand interface, buy the JK BMS. Does it all, does it perfectly, can do CAN communications, but does not have native Pylontech protocol built in, so can't automatically talk to most inverters

If you don't need a BMS, buy the NEEY smart active balancer, with bluetooth, app and also very easy to use interface

If you do need a BMS that has native Pylontech protocol so it can talk to most inverters and control them, there are very few options that I know of. Seplos is one of them (but then you'd also need an active balancer really) Are there any others?

graememk

https://www.boards.ie/discussion/comment/120083600#Comment_120083600

There's one, maybe 2.

Rec bms - no active balancing

Maybe diybms but that's a whole other thing.

The seplos for the me3000 communication and leave the balancing to the neey ,( and only balance on the top end)

unkel

I'm reluctant to get a Seplos again, we didn't get on. Although some of my frustration was caused by my faulty ME3000SP failing to communicate.

I'd pay good money for a BMS that can do it all. A JK BMS with native Pylontech comms would be perfect.

randombar

So Neey worth it with the Seplos/Sofar ? Not sure what balancing the top end means?

unkel

Came across this alternative to the Seplos while browsing AliExpress

https://www.aliexpress.com/item/1005004742920995.html?

No idea if any good, will do a bit of Googling

graememk

https://www.boards.ie/discussion/comment/120083785#Comment_120083785

Keep an eye on the voltages and play it by ear.

What I mean it only balances when above 3.4v

If you balance on the low voltage, it can actually unbalance the battery.

SD_DRACULA

https://www.boards.ie/discussion/comment/120083681#Comment_120083681

What bms are you using now?

A bit mad that there are not a plethora of options out there for DIY batteries by now.

unkel

https://www.boards.ie/discussion/comment/120084613#Comment_120084613

Agreed. At the moment I am using a NEEY active balancer and the BMS between my ears. I bought a JK BMS, tested it with a test 16S battery last week, very impressive, well made with a closed case, can handle 200A, easy to use, good menus, built in 2A active balancing, temp protection, RS485 + CAN support, bluetooth with good app in the store, but no native communications using Pylontech protocol (which is what you need for talking to your inverter - Seplos DOES have this). But I did find someone who had built a hardware interface for this, should work for a large range of inverters like Solis, Sofar, Goodwe, Deye (Sunsynk) etc. shared on GitHub.

Exploring this option now, seems like the perfect solution, in the absence of a commercially available product that can do it all

slave1

https://www.boards.ie/discussion/comment/120084613#Comment_120084613

Looks at all the battery bank reviews on YouTube and you can see the majority of them are working off the Seplos BMS albeit different custom firmware, it's so recognisable as the light diodes and dip switches and communication ports are a give away

unkel

https://www.boards.ie/discussion/comment/120084829#Comment_120084829

They have to. Seplos is the only commercially available BMS for reasonable money with built in CAN with native Pylontech protocol communication - the only one that can talk to inverters

If only there were a far better BMS with active balancing out there that could do all that 😁

championc

I think that, should you have more storage than you need, and never need the full 85% capacity in one day, then the need for getting the max capacity diminishes.

It's likely therefore, if your consumption exceeds your capacity, that it's likely only for Dec and Jan on poor days.

graememk

https://www.boards.ie/discussion/comment/120084940#Comment_120084940

Let's not give pylontech the credit, it's the SMA protocol at heart most of the batteries use. The other battery manufacturers just added extra bits on.

irishchris

Forgive me if done something stupid but been a while since logged into BMS. can't seem to login in to the battery monitor as continually comes up with port does not exist. Restarted pc and BMS, ran as administrator, selected baud rate of 19200 but no com port to select. Used different ethernet cable.

Anyone any idea what I'm missing?

slave1

Dodgy cable, mine was so I stripped it and re terminated and all good.

I assume you mean the com port is greyed out and you tried all USB ports (I can never remember which one so just keep plugging in and out)

unkel

Open control panel -> device manager and then plug in your USB stick. It will come up and show you which COM port it is on.

noelocon

Hi,

I've got a Sofar ME3000, Seplos and 16s48V200H which has taken quite a while and diagnostic effort to get working.

At the moment everything is working but I'm seeing the same issue that @E30M3 and @munsterfan2 had where the SOC and voltage drop off a cliff 90% to 10+% in minutes when discharging and the slowly charge until the SOC shoots back up to 100%

From reading the forum I can't figure out how to how to fix this issue. The batteries were fully top balanced a few weeks ago.

Any idea how to rectify this ?

graememk

https://www.boards.ie/discussion/comment/120130905#Comment_120130905

It's the voltages of your cells, they are falling through the floor. (And somewhat across the board.

One thing to see is verify that the seplos is reading the voltage correctly. Start discharging and put a multi meter on the cells.

If they match.. unfortunately the short circuit killed the batteries

unkel

Do you remember what happened after 17:00? Perhaps your ME3000SP was providing 3kW for your houseload. Could cause quite a big voltage drop. And if that lasted for near half an hour, it would have taken quite a chunk out of your battery, explaining it going from 3.3V to 3.2V per cell

Also, I wouldn't trust what the Seplos tells you the voltages are. Measure at the cells themselves with a multimeter