286Ah 10,5kWh capacitor heltec BMS powerwall

Lithiumseller

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This is my main powerwall I will add more cells, more than 10 000pcs.
Heltec capacitor BMS is running very cool when touching it, and it balances 5.5A, 0,003v accuracy. It seems to be most lossless BMS ever made. I do not need Batrium bms anymore. 2800 cells in 14s 200p Easun solar 5kw. ANT BMS 200A 14s for temperature sensing and auto cut off, for discharging and charging.


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Lithiumseller said:
This is my main powerwall I will add more cells, more than 10 000pcs.
Heltec capacitor BMS is running very cool when touching it, and it balances 5.5A, 0,003v accuracy. It seems to be most lossless BMS ever made. I do not need Batrium bms anymore. 2800 cells in 14s 200p Easun solar 5kw.


image_cvokty.jpg

image_cmoyyu.jpg

image_puczhi.jpg

image_xlujhx.jpg

image_adtoys.jpg

image_nobjsq.jpg

image_bxnxtb.jpg

image_ngveap.jpg

image_clqczh.jpg

image_reksrk.jpg

image_fvdtmo.jpg
Is it the Active Balancer that is cool to the touch or the BMS.
I looked on their website and don't see very good specs for what they are calling a BMS.

Is it programmable?
 
What's in an acronym?

Lets take for example BMS.
BMS (Battery Management System)

What does it mean?
To be sure it means a lot of different things.
In its most rudimentary form it means it manages your batteries and at least maintains an equalization of all the cells/packs.
That's it nothing more nothing less.

There is also the "BMS" that manages your charge cut off, discharge cut off, active /passive balancing temperature control and reporting. Most of them are through bluetooth and if you are not in the "bluetooth broadcast bubble you are out of luck. Takes a bit of programing and know how to get the info to a local database for later review but it is duable.

Then there is the "BMS" that does it all. Wifi connectivity, charge controller integration and support, inverter integration and support, shunt trip and panic stop settings, cooling triggers , heating triggers, over and undervoltage triggers for shunt trip and so on.

So the acronym "BMS" can mean a whole host of things. Whateverthe "BMS' is, as long as youare comfortable with it, that is the important factor.

I for one want a 'BMS with as many options as possible to protect my valuable asset. My hard earned batteries that I spent countless hours testing and vetting to be sure that they can perform in my powerwall. I am certainly not going to trust them to a minimalistic "BMS".

Wolf
 
Heltec active balancer is cool, when touching it. Heltec BMS is not programmable it is actively balancing always no matter what cell voltage 1.8-4.5v discharging and charging always active.
 
You Still need a bms. Balancing is just a function within most bms system.

That balancer is not a bms though.
 
Looks like a very good start

Is that an ANt bms I see? 3rd pic
later floyd
 
So question I just thought of.... the pack is well balanced does the BMS run cooler?

Does active higher balance current have a 2nd benefit. ... Longer BMS life?
 
Thing is that an active balancer will transfer energy ALL the time. Its not much but its basically all the time (Of course based on voltage diff)
2nd life batteries will diff alot if you have a wide voltage span during daily use so you will balance alot... This wastes energy each day since they arent 100% efficient... A passive balancer only balances when they actively drift and that happens due to uneven packs or with self discharger..

Active balancer lengthen the discharge depth available but wastes a bit more energy over time
Passive balancer is the oposite.

Thats the difference on 2nd hand battery packs and im pretty confident that for most use cases active isnt needed since they cost more. The worst is that the cheaper ones hides how much they balance so you dont know how much they drift...

Still they have their use cases :)


Higher balance current on active balancers makes it possible to discharge or charge faster in the ends.

you wont feel any heat on any balancer if you ask me. If you can do that they balance really hard and you have issues!
 
Bubba said:
So question I just thought of.... the pack is well balanced does the BMS run cooler?

Does active higher balance current have a 2nd benefit. ... Longer BMS life?
Heltec capacitor active equalizer is running abouttemperature like25c, active balancer benefit is to have equal cycle life for lithium cells and when discharging there is no cell block what gets empty before others.
 
Lithiumseller said:
Heltec capacitor active equalizer is running abouttemperature like25c, active balancer benefit is to have equal cycle life for lithium cells and when discharging there is no cell block what gets empty before others.
Hmm it looks to me that this active balancer will basically hide an underperforming pack.
Now Lithiumseller please do not take this the wrong way as any thing to educate us and make our packs perform better is always a good discussion.
I on the other hand am struggling to see the advantages of this balancing unit.
So taking the scenario of a 4s batterywith "100Ah" and you have 1 pack at 80Ah one at 120Ah one at 100Ah and one at 90Ah. the 120Ah pack will be constantly giving up energy to maintain a "balance". Am I wrong here?
Also is there any reporting at all with this balancer? I do not see anything in the description. It would be nice to know how much "active balancing" is actually happening to determine if there is a pack in trouble.
If a battery is built with a properbalance of the packs to begin with as in 100AH 5Ah for each thenactive balancing really is not necessary as the individualpack voltagewhen getting close to DOD (3.5V) will be relatively close as in 0.05v 0.03v. As the Battery charges the packs will start to tighten up all by themselves and if any top balancing is needed it will be very little.
The weather has been dismal in the US north-east over the last couple of days but these charts will show you the point I am trying to make.
This was the solar curve of my 14s pack yesterday as you can see my battery this AM is depleted and idling at 14.5 SOC voltage are between 3.420 and 3.500.

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During yesterday's brief encounter with the sun my system started to charge and the cells tighten up. Here is a closeup of the voltages between 14:00 hrs and 15:00 hrs as you can see 0.032 voltage difference with absolutely no balancing required.

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As the system approaches 4.1V this self equalization just gets tighter with a full charge showing 0.010.01 difference again no balancing interaction required.
This trace was taken in august when I had plenty of sun.

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Now if you have Frankenstein packs (ones with a multitude of cells from different manufactures)and the cells mAh results,IR andSOH are all over the place. Alsoif the packs where thrown together with minimalattention payed to sorting mAh and trying to equalisethen if you do go below ?3.4v there will be a seperation of voltage some of it rather dramatic. So yes there I can see the use of an active balancer but then again is it hiding something? I don't know.

Does the ANT BMS have any reporting so you can track the performance of the whole battery and the individual packs? If so do you have any data you can share?
Thanks for all your input and info so far. Nice start on a 14s100p X2 Battery. :D
Wolf
 
Lithiumseller said:
Bubba said:
So question I just thought of.... the pack is well balanced does the BMS run cooler?

Does active higher balance current have a 2nd benefit. ... Longer BMS life?
Heltec capacitor active equalizer is running abouttemperature like25c, active balancer benefit is to have equal cycle life for lithium cells and when discharging there is no cell block what gets empty before others.
Healthy packs don't need activebalancing in my experience - its amazing. I have 84 packs that cycle every day and I've not done any balancing since April 25th 2020 when I added the most recent 14 packs, balanced them in and turned balancing off. They have drifted 10mv since then - within the 'margin of error' one might say as packs seem to take a bit to 'settle in' after an initial balance. The battery bank has delivered 3,681kwh(s) of power since then - so the battery bank is not sitting idle.

IMHO and to echo some of what @Daromer said above- I think its a misdirection to go the active balancing route as it

- Wastes energy on something that's not needed
- I can't see any theory as to why it wouldextend the life of the battery bank - only adds more stress as balance current is induced
- Couldhidea failing pack (to the limit of the active balancing)that needs attention... I'd rather have thegradual warning (e.g. balance drifting)than hide it till its a serious failure

I get the 'idea'... its predicated on the idea that packs need balancing... but that's not true if the packs are healthy and matched within a battery.
 
I use an active balancer as well and I agree with some of the statements regarding drift and the advantage of active balancing. My packs do not drift as well since they were made with similar cells. Some balancers are not programmable, but some are. The current one I use are set to 40mV difference, but my packs never go over that value. So in this case it never get to the point it balances. The JKBMS I will be using next is actually programmable so you can set it to a point where you can have it balance. Therefore it's not balancing all the time. So at the same time it is true that a correctly built pack doesn't require much balancing. Also I don't go past 70% depth of discharge, so the wild swings on voltages usually happen if I go 90% depth of discharge where the small difference in mismatched capacities start to show.

But the real reason for me why I got the board was to build my own BMS, since it does the voltage reporting for me. Through my raspberry pi I also have relays that fire off during events, and emails that go out when threshold are met. It also allows me to graph on graphana. My board only cost me under $100 so it was an inexpensive purchase.
 
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