How the Seplos BMS handles balancing. (it actually sucks🤦‍♂️)

Now, after a full charge again, we want to have a look how the BMS balances the cells. What can I say?! Even after 2 hours sitting on 56V, the voltage difference has only decreased by a tiny tiny bit. The balancing of this BMS really sucks 🤷‍♂️ It seems to have far less than 150mA of balance current and has pretty much no effect on these cells. I have charged the pack to 58V, so really in the top steep area of the charging curve, and even here, the Seplos BMS cannot balance the cells effectively.
Even the QUCC BMS in the good old days had a better balance outcome.

I had very little hope in this BMS from the beginning but the reality is even... well, see for yourself!
I don't know what to say about this BMS but it definitely cannot live up to its hype.

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[DanBurgaud]

14:24 "... BMSes with 40, 50, 80ma balance current ... "
And then installed on 100AH, 200AH, 300AH battery of all that...
100ma balancing would take 10hours just to balance out 1AH of capacity deviation...

[natesdiysolar]

This is exactly what I'm experiencing right now. Very frustrating. FYI there is a BT app.. I had mine on the charger with that intermittent charging for 20hrs and no change
.. ..

[awesomusmaximus]

Great job bro
The only way to keep the cells in perfect balance is for the balancer to know usable ah in each cell that unfortunately requires one shunt for each battery

[timos]

Das sind "Plug in and forget" Batterien. Bei deinem ersten test hast du ja ein paar Zellen getestet, das waren genau die die dir danach probleme gemacht haben. Theoretisch müsstest jetzt noch so einen kaufen und ohne mit den Zellen zu spielen das ding zusammen bauen und testen. Auch ist es unüblich die Zellen von 2, 5V bis 3, 65V zu benutzen...
Stell sie einfach beide in die Ecke, schließ sie an und lass sie mitlaufen. Guck nach einem Monat nach, wie es mit den zellspannungen aussieht und fertig. Ich selbst nutze ja die Pylontech. Anschließen, anschalten und vergessen. Läuft seit Jahren ohne Probleme, auch mit 100mA passiven balancer... so lang sie im "Normalen Bereich" betrieben werden und nicht unteres minimum oder oberes maximum um sogar den balancer zur Schutzabschaltung zu zwingen gibt es keine Probleme.

[jasonbroom]

You start out the video showing a very small 20mv of deviation across 16 cells...and then you say you don't think this BMS is balancing? I'm more than a quarter of the way through the video and still trying to find the part where it "sucks". Charge to 3.4v or 3.45v per cell and don't obsess over such small deviations?

Is anyone able to cite a peer-reviewed paper, showing what level of cell deviation is acceptable across packs of varying sizes? The only thing I have found is manufacturers stating 2% or less (3.65*.02=.073), so does that mean anything around 75mv of deviation is considered good?

It seems to me like you are desperately trying to find something wrong and are disappointed to find that it's all working within perfectly safe and suitable parameters. This is not like your usual work.

[kooscombrinck]

Thanx Andy! I was in discussion with a Seplos agent the last week and they think their stuff is great! Your testing put the proof next to the pudding. I think JK is tops so far out of your your testing, I planning my own Solar DIY project for our home here in Sunny Hot Free State in SA. I have gain a lot of info from your channel and WILL abuse it to my my gain!👽👽👽👽👽

[Irilia_neko]

Take off the BMS, and replace it by a jk-bms 🤣🤣🤣

[evil]

Good job, vid, data, thanks Andy, this is very helpful info. Seplos needs to pick up their act, I hope they are listening and responsive, but many previous comments have shown that they are not.
The Battery Build is mostly really good and solid, it looks great, but their; Communication, Packaging, BackupSevice, Instructional Dialect, PC necessity, No B/T app, and Passive Balancing SUCK!
I have 3 x Seplos 5Kw “Suntorque” batteries, 2 of these steadily decreased from new, and after a few months were down to only charging to 64%, Until I watched your recent series on Seplos gear and done some more research. I completely discharged each battery till the inverter shut down & then recharged them back to 94% & 96% respectively after the first time I did this. I bought these batteries because they were advertised as ‘Plug N Play’, no need for comms etc, but they really are not that simple.
SEPLOS, do yourself & everyone a favour, listen to Andy and make the necessary changes, or you will lose the race. I would like to buy one of these kits for some 310A cells I have, but I would have to consider making some mods & adding an active balancer, which I dont believe I should have to do at this price point.
Thanks for ur great vids & info

[bilalbhatti]

It'll balance off after it hits 3.56v and then it balances and trickle down to 98.5% .. and restricted charge starts again with 7-3 amps.. and then it auto charges with 300 waats. And stops at55-5v to 54v brings down to 53.5v while balancing .. charging with, 58.4v.. so that it uses it's resistance with it and gives around, 55.5v at load stage

[adibu]

yup, that it what it does.If one cell charges quicker it will turn off all charging. This is what mine does with same BMS.. Probably I need to balance it manually.

[bilalbhatti]

It stops at 3.55v and shows 100% SOC.. and other lower cell is like 3.3 v.. 200-300 mv diff with my 100amps

[bilalbhatti]

It'll balance off after it hits 3.56v and then it balances and trickle down to 98.5%

[jaroslavchytil]

Hi Andy, its a shame that you probably got the wrong BMS version (and Seplos should act!), or i dont understand why you are having such problems. I have two battery packs (not seplos kit but just BMS) and dont have these issues, i can charge/discharge around 80A without any warning and all time cell deviation is around 8-15mV. Luckily you have your own battery sets with different bms which works for you like charm.

[repairmanbe]

150 - 160mA balancer to balance a ~280Ah cell - does not even tickle the cell! Seplos go back to the drawing board and produce a sensible device to do the job.

[nunyabusiness]

This will sound like throwing good money after bad, but the "NEEEEYYY" Gen4 sounds like a good fit for this BMS, it will address the balance current shortcomings and give BT interface to monitor cells status and allow tweaking of balance parameters. I imagine that once the safety thresholds in the BMS are set (via PC) there would be little need to mess with them. The Neey may/should be able to tame the runaway cells that trip the warnings and protection messages....

[USA-GreedyMenOfNoIntegrity]

It's no better than Junk Daly BMS at 150 mA. The old "Intermittent Power" bs, where it shuts off for 2 to 8 hours. I will never buy another Seplos. Three JK's just came in. Set them up and test them on a test battery, with a test load, in about 15 minutes ea. LCD 4.3" love it.

[Blueworld]

Hi Andy, my cells are not balanced, can you suggest a balancer for top balancing
I have 8 cells of 3.3v with 200Ah

[ipstacks]

A lot of these balancers were designed for bicycle batteries or similar. What Andy is showing us here is an “under powered” balancer isn’t ever going to get the job done with batteries that are higher voltages and higher capacity (by a large margin). These under powered balancers have multiple problems like only discharging / charging one cell at a time, not discharging / charging with enough capacity to make a meaningful difference and silly settings that with smaller capacity batteries might be okay, but at this scale all of this leads to an unacceptable underperformance that needs attention.

[rogerlittlejohn]

I have had my Seplos bus for months, and find that it does not balance. I have three batteries that run higher than all the others and two that run lower.

[milan]

So final result - Seplos BMS don't take?