Work in Progress - But it's alive!

[Lt.Dan]

This is adjustable. I feel like the default settings are pretty bad on the Seplos BMS. And the documentation leaves a lot to be desired too.

I agree the default settings on the Seplos are very poor. I change most of them.

I have some 3 year old 271ah CATL Grade B cells that are now capacity testing 245-250ah, and the Seplos BMS has no problem keeping them within 15mV at 3.5v/cell.

The Seplos BMS is capable of 200mA of balance current, the only factor is how long you give it to balance every day. I try to give my battery atleast 1 hour and it has no problem.

 

[weirded]

I agree the default settings on the Seplos are very poor. I change most of them.

I have some 3 year old 271ah CATL Grade B cells that are now capacity testing 245-250ah, and the Seplos BMS has no problem keeping them within 15mV at 3.5v/cell.

The Seplos BMS is capable of 200mA of balance current, the only factor is how long you give it to balance every day. I try to give my battery atleast 1 hour and it has no problem.

Do you remember what specifically you changed on the Seplos configuration?

 

[Lt.Dan]

Do you remember what specifically you changed on the Seplos configuration?

Almost all of it lol. I'm out of town on vacation right now. I have a template saved for my own batteries.

I think Andy from Off Grid Garage has all of his in a Google Drive, and it's pretty close to what I used

 

[weirded]

Almost all of it lol. I'm out of town on vacation right now. I have a template saved for my own batteries.

I think Andy from Off Grid Garage has all of his in a Google Drive, and it's pretty close to what I used

I’ll look that up. First I’ve gotta recover the config on my Outback inverters though. The SD card broke and all config was lost. Ugh.

 

[Quattrohead]

Pressure is current, monimor is volts ?
I think there is a language file kicking around somewhere that converts these to proper English.
I don't know ??? I'm still trying to get my head around these Seplos BMS but I do now have all four of them talking to either solar assistant or their own monitoring software.

 

[Steve_S]

Active balancing is the funnest controversy in DIY battery building.

Afaik the DIY EV building scene does not use them and they deal with larger packs with many more cells.

Huge difference... Apples to Watermellons.
EV's use Smaller Cells and many more, they are also fully matched & batched to have identical IR throughout their entire working voltage range (regardless of chemistry) and some automotive BMS have internal balancing functions.

 

[Skypower]

Fair enough. At this point, for my setup it seems to be a (possibly lazy) way to improve things with little additional effort - and they’re not that expensive in the bigger scheme of things. Was able to grab the NEEY 4th gen open box for $110 shipped from the US.

You’ll love it, the thing’s a brut. Won’t need much time at absorb voltage to git-er-dun. Consider disabling the passive balancer in the bms when using the Neey.

 

[Steve_S]

Consider disabling the passive balancer in the bms when using the Neey.

HELL YEAH !!! Passive next to Active makes for some really weird shyte to happen, oivey ! Learned that with a QNBBM-8S Active next to a HelTec Passive Capacitance Balancer. Not Good !

 

[WindWizard]

Sun came out today, got a first charge into it. Looks like the cells have gone out of balance quite a bit. Now shopping for an active balancer...

It looks like Cell 12 is starting to run away on you. One solution that works well is to discharge the Cell with the highest voltage with a cheap light bulb attached to some alligator clips. After you balance them then your Seplos should be able to keep them balanced.

I use an active balancer on my pack. I only turn it on when the Cells are over 3.4 volts.

https://www.amazon.com/gp/product/B076MKZS35/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[hwy17]

You’ll love it, the thing’s a brut. Won’t need much time at absorb voltage to git-er-dun. Consider disabling the passive balancer in the bms when using the Neey.

DIY EV's are using 280's now as well. And a lot of their sources aren't necessarily more reliably matched and batched any better than a good quality DIY ESS cell order.

But this is what makes it the funnest debate for me. Well informed people appear to still disagree on it. I haven't run my DIY pack yet to form my own opinion.

 

[weirded]

Pressure is current, monimor is volts ?
I think there is a language file kicking around somewhere that converts these to proper English.
I don't know ??? I'm still trying to get my head around these Seplos BMS but I do now have all four of them talking to either solar assistant or their own monitoring software.

Ohhh I need to dig around for that one. That would make life a lot easier.

 

[weirded]

Just closing the loop on the balancing - the NEEY 4A balancer has done a great job balancing these out:

 

[houseofancients]

Sun came out today, got a first charge into it. Looks like the cells have gone out of balance quite a bit. Now shopping for an active balancer...

View attachment 184613

95 mv might be doable for the BMS, provided you give the batteries some time ( 24-48) to take a constant charge of 3.5)
Really surprised it isn't more, these were some good cells !

 

[Quattrohead]

That is fantastic, I'm glad it all worked out in the end.

 

[Alkaline]

Active balancers are flipping great, plug and leave them plugged I never seen the need to unplug them. They took the same time to balance with or without the switch.

Any time I see people complain its almost always an install error. I have put the little heltec style 4s balancer on at least 11 SOK batteries for our local fishing group and everyone has said they love there battery now. No issues with imbalance. And previously I had 3 on 3x 8s banks with overkill solar 8s bms units. These were grade B cells and without them they would not be usable IMHO.

I think people put the blame of grade B self discharge on AB unfairly.

 

[weirded]

Active balancers are flipping great, plug and leave them plugged I never seen the need to unplug them. They took the same time to balance with or without the switch.

Any time I see people complain its almost always an install error. I have put the little heltec style 4s balancer on at least 11 SOK batteries for our local fishing group and everyone has said they love there battery now. No issues with imbalance. And previously I had 3 on 3x 8s banks with overkill solar 8s bms units. These were grade B cells and without them they would not be usable IMHO.

I think people put the blame of grade B self discharge on AB unfairly.

I followed Andy's advice (off grid garage Australia) on configuring the NEEY to turn on at 3.45V and back off at 3.40V... And that seems to have worked okay.

To be transparent, I haven't really cycled this pack yet, I am still working on rebuilding my DC distribution before I go through the trouble of unbypassing the house (which is annoying because a few clocks in the house go to 00:00, etc). Will report back once I have a few cycles in it.