Seplos V3 BMS and Active Balancer Wiring Video

[...Ghost...]

Hi All.

If you need help wiring your Seplos V3 BMS and Active Balancer, here is a video I made of the process I found worked best.

 

[SwwilsSolarMan]

This video helped me out when I did mine, thankyou!

 

[Franek]

Ok

 

[Haysdb]

Does the active balancer work? Is it on all the time or only above some voltage? I have two Seplos 104-L batteries on the way and I’m wondering whether I should even enable the active balancer. It appears it is off by default with the start deviation set to 500mv.

 

[pfeva134]

Does the active balancer work? Is it on all the time or only above some voltage? I have two Seplos 104-L batteries on the way and I’m wondering whether I should even enable the active balancer. It appears it is off by default with the start deviation set to 500mv.

Yes it works, but not how you think I suggest not connecting it at all, because it may ruin your balancing and degrade your pack quicker

 

[bolhuijo]

It would be very difficult for the Seplos balancer to cause any trouble IMHO. Mostly because it is quite manual: you must press the power button to enable the balancer board. It sits in standby mode for up to 10 hours. If it does not receive a signal from the BMS to begin balancing in that time frame, it shuts itself off. You may disagree with the hardcoded thresholds it comes programmed with but it seems unlikely to cause harm.

from the manual for the curious:

 

[pfeva134]

It would be very difficult for the Seplos balancer to cause any trouble IMHO. Mostly because it is quite manual: you must press the power button to enable the balancer board. It sits in standby mode for up to 10 hours. If it does not receive a signal from the BMS to begin balancing in that time frame, it shuts itself off. You may disagree with the hardcoded thresholds it comes programmed with but it seems unlikely to cause harm.

from the manual for the curious:
View attachment 262318

You're absolutely wrong, it does disbalance the pack, that's what i had. It is not only triggered by button but also by BMS via dry contact

 

[bolhuijo]

You're absolutely wrong, it does disbalance the pack, that's what i had. It is not only triggered by button but also by BMS via dry contact

The dry contact does nothing if it isn't turned on though, as far as I can tell. Mine spends all of its time off, my pack hasn't deviated more than 10mV in the several months since original startup.

 

[pfeva134]

The dry contact does nothing if it isn't turned on though, as far as I can tell. Mine spends all of its time off, my pack hasn't deviated more than 10mV in the several months since original startup.

Wrong again, you need to configure cell difference settings for dry contact to work. But even if you leave it disconnected from BMS and use button to trigger, it will unbalance pack if you discharge it well enough. Also 30mV threshold is laughable.

 

[bolhuijo]

Ok then

 

[Haysdb]

Yes it works, but not how you think I suggest not connecting it at all, because it may ruin your balancing and degrade your pack quicker

Elaborate on “not how you think”.

The batteries I’m getting are said to include the 2A active balancer but I’ve not seen any indication of a button to activate it. There may be one, it’s just not visible in any of the product photos.

How is is activated by the BMS?

There’s been a lot of mud slung toward this product but I’m still looking for details on when it’s activated, how it works, and how it unbalances cells rather than balancing them. Also, how is it enabled or disabled? Parameters 100 and 101? Does it use parameters 80 or 81?

 

[pfeva134]

Elaborate on “not how you think”.

The batteries I’m getting are said to include the 2A active balancer but I’ve not seen any indication of a button to activate it. There may be one, it’s just not visible in any of the product photos.

How is is activated by the BMS?

There’s been a lot of mud slung toward this product but I’m still looking for details on when it’s activated, how it works, and how it unbalances cells rather than balancing them. Also, how is it enabled or disabled? Parameters 100 and 101? Does it use parameters 80 or 81?

Sure, if you open balancing board documentation - you'll see it has multiple connectors.
One of them labeled as dry contact - that one can be connected to BMS, which will switch balancer to standby mode
Another is labeled as a switch - that one you can connect to external button.

If you configure parameters 100 and 101 in BMS studio - cell diff pressure alarm and recovery, this will trigger dry contact for active balancer board. you can set it to any value like 50- 20 does not matter, as long as it is something reasonable.

However, it only switches board on into standby mode! It does not mean it will start balancing. Balancing parameters are fixed in balancing board itself.

So, once balancing board is in standby mode - you'll have button flashing. Once cell difference is above 50mV, balancing board will start balancing until the difference is 30mV. Also, keep in mind, that it doesn't care what cell voltage and will start balancing on voltages down to 2.9v, which will unbalance your pack even more.

NOTE: those equalization parameters (80-83) are for BMS board PASSIVE BALANCER ONLY! You can completely ignore it as it does balancing with like 200ma or something, it is nothing to do with active balancer!

I took me a lot of time and trial and error to figure out the logic on how it works as documentation is non existent. I'm going to get NEEY balancer myself to replace seplos

 

[Haysdb]

Thank you for the description. Why does it unbalance cells? That’s not good that it’s turned on at low voltages. That seems like something that could be fixed with a software update. Does it help to stop discharge at like 3.0v or something before the cell voltages get too far apart and then charge to a level where they do start to spread apart?

I will maybe play around with it but it seems others have done that and simply not been able to get it to work, so I might just stick with the passive balancer and then consider something like the Neey if I see cells getting far out of balance.

 

[HughF]

It’s not even connected to the BMS in my v3 setups, completely separate and activated by the button on the back.

I don’t use it.

 

[bolhuijo]

We should bridge this thread with this one: https://diysolarforum.com/threads/seplos-mason-kit-and-lf280k-with-v3-active-balancer.80083/
so that all the nearly correct information is in the same place.

I continue to update my own notes on this. The truth is out there. I wish we had a pinout on the dry contact 4-wire interface.
If I could summarize what we have learned so far, it is that this active balancer, once triggered, will happily continue operating even as the pack discharges toward 2.9V/cell which is way lower than recommended. Because the active balance board has no programmable options, you may wish to disconnect the 4-wire cable linking it to the BMS dry contacts and trigger it only via the manual power button. As a reminder, print a label and affix it near the button that says, "only activate when battery is >=3.4V/cell" or other verbiage of your choosing.