Hi @bearcatcrazy1971, We have pushed the new BMS firmware, and based on our experience, the new firmware resolves the issue for most users.
For cases where the problem persists, it may be due to objective differences in conditions or issues during the upgrade process. We recommend following the steps I provided earlier to complete the upgrade.
If the issue still isn’t resolved, we can roll back to the previous version upon your request. Rest assured, we will take full responsibility for this matter.
I have already carried out several BMS updates with calibration, but it has not improved.
And the problem has existed for almost 2 years now, since I have been operating two B230s on the AC200MAX.
It is noticeable that it always affects the same B230 battery.
Hi @jockel66, We would like to confirm whether your calibration procedure follows the correct guidelines after the upgrade.
When upgrading, please disconnect the AC200MAX from the B230 and upgrade the AC200MAX separately. Meanwhile, please do not load any device when upgrading it.
Additionally, if the issue persists with a specific B230, we recommend discharging that B230 separately, then charging it to 100%, and finally reconnecting it to the AC200MAX.
Please also note that slight differences in each battery voltage can occur, which may cause variations in charging and discharging speeds. A certain degree of SOC (State of Charge) difference is normal and acceptable for usage.
Hi @jockel66 and @jCs, We completely understand your concern about this issue. In fact, objective discrepancies do exist, but they have minimal impact on actual usage.
In our perspective, the AC200MAX and the B230 battery pack are designed to function as a unified system. Therefore, we focus more on the overall performance of the system rather than on individual SOC discrepancies.
If the entire system can charge to 100% and discharge to 0%, we consider it to be functioning normally.
The SOC difference arises due to the inherent characteristics of the product. Our batteries use premium lithium iron phosphate (LiFePO4), which is exist the inconsistency among cells. This inconsistency stems from the high internal resistance of LiFePO4 batteries. Each cell’s internal resistance varies slightly, causing some energy to be consumed by internal resistance during charging and discharging. Over time, this leads to increasing discrepancies in the charge levels of individual cells.
Additionally, during the redox reactions, ferrous iron (Fe²⁺) may oxidize to ferric iron (Fe³⁺) or reduce to metallic iron, potentially altering the internal resistance of the battery.
Coupled with SOC measurement error, overcharging or over-discharging individual cells can further affect internal resistance. This may eventually result in varying SOC levels among the four cells in a battery, which is a common manifestation of LiFePO4 cell inconsistency.
@BLUETTI_CARE
→ Unfortunately several of your systems (including those using the B230) do not automatically turn on expansion batteries once they go to 0 SOC, thereby requiring manual intervention.
→ In theory it sounds good that “the whole sytem is what matters, not individual SOC or differences”, but in practice that is unhelpful for many of your systems, because expansion batteries will shut down and not turn back on automatically.
→ It’s possible you’re saying that they will all go to 0% at the same time, even if they show large SOC difference at some point – but in my experience (and many others’ experience) that isn’t that case. And degradation over time is okay too – as long as batteries can turn back On. But if they can’t, it’s problematic to have 40-50% SOC difference.
→ So an expansion battery going to 0 charge earlier than the rest of the system does matter.
→ If one battery is used in an unbalanced fashion and goes to 0 much earlier than others, it will shut down, and that system capacity is lost unless there’s manual intervention. In contrast, with more even discharging none shut down significantly prematurely, and the full system capacity is kept without requiring manual intervention.
We users can visually see when a pack gets to 0% and shuts down…why can’t the system also know this and prevent draining a specific expansion pack, to prevent it from shutting down if SOC difference is very large? A battery will only shut down when at 0%, not at say 20%, so there is much room for error in detecting this…
→ A person buys a battery system to have it run reliably, and baby sitting it because some B230 drain to 0 much earlier than the rest of the system is not practical , especially if charging with solar.
→ The user shouldn’t have to manually make up for the problems arising from SOC differences.
→ (For reading ease, it would be nice if posts wouldn’t automatically remove “spaces” that we put in between paragraphs. Even “indentation spaces” are removed.)
Hi @jCs, Thank you for your insightful feedback!
Based on your response, it’s clear that you are an expert in the solar energy field! Additionally, you have a deep understanding of our products.
The issues you raised are something we’ve also noted, but since the AC200MAX is an earlier product, it was initially designed as a portable power station without considering such specific usage scenarios. Indeed, the B230 cannot be activated through the main unit and needs to be manually powered on, which makes it less suitable for long-term unattended use.
To improve the customer experience, we continue to develop new products. The new AC200L + B300K model significantly enhances user experience. After the system is powered off, it can automatically activate the entire unit when powered on again, and also ensures better SOC balancing. If customers are particularly concerned about these issues, we recommend upgrading to the newer models.
If you ever have more suggestions or questions, feel free to share them with us!
@BLUETTI_CARE
I understand that your newer products solve these issues but most people (including me) roughly cannot afford spending $6000 to $7000 every 2 years buying upgraded systems and even then here’s the question : what to do with the old AC200MAX hardware ???
It does not work like this and we as customers are stuck with the AC200MAX now … so it is not a very nice/satisfactory answer for us as customers to hear in my opinion…
Which leads me to my next point : I upgraded to BMS 1017.07 and I noticed the following (after completely discharging to 0% and recharging from the grid)
charging : I charged from 0% SOC with the included adapter so contiuously around 300Watts. I noticed that the charge was evenly spread over the 3 packs until reaching 100%. Unfortunately at this time of the year (it is winter here in Belgium) I do not get much sun to test solar charging.
discharging: SOC percentage of the 3 packs stayed pretty much equal until 60%. At night the Bluetti stays on DC power so it does not shut down. I do that so that I do not have to power both B230’s on every day and also to keep the Bluetooth connection with my HomeAssistant Raspberry Pi active during night…
So this morning there already was a 11% difference between Pack2 and the others.
Pack1 58% SOC
Pack2 49% SOC
Pack3 56% SOC
So this means that (even when powered on but in “rest” state) just keeping the system on at night does not really drain Pack 2 (because it still has the hightest Voltage) but changes the SOC % of Pack 2 ???
Further on this morning I used some AC OUTPUT current (washing machine using 500-1000 Watts during 30 minutes) and then I see that the gap between SOC% of Pack2 gets bigger in comparison to the other Packs .
The Pack voltages however are pretty close to each other (so then again the SOC calculation is off here ?)…
So far I cannot make any decisive conclusions so I will continue monitoring for some time but note that overnight SOC calculation of Pack 2 is going wrong in comparison to the other Packs…
Going back to your latest reply : by buying your products “we” (=customers) committed ourselves to your brand and we hope that you do everything necessary to keep us a happy customer…
Therefore Bluetti must always strive to find solutions to solve most of the issues that many owners of the AC200MAX/P + B230.
I can live with the fact that B230 shuts down when 0% SOC…
I also understand that SOC calculation can be hard due to the LiFePo characteristics and internal resistance and every pack is different… but I have 2 questions regarding this
if you look at the image above, what value is correct ? Pack Voltage or SOC% ? I would say Voltage is correct
what value is decisive to shut down B230 ? SOC or Voltage ? Because in my case it would mean that Pack 2 will be shut down first even while it has the highest voltage ? Does not seem logical to me…
So please keep up investigating and maybe most issues can still be ironed out and give us a better product (which I am already happy about but solving those little inconsistencies would make it even better)
@jockel66
yes it is always Pack 2 that is lowest in SOC% (but not Voltage if you look at my screenshot). In the past I also switched B230 packs to see if it was 1 specific pack that had an issue but it was the same result.
And that was with the older firmware BMS 1017.02 still installed
So it is not pack related and with BMS 1017.07 the behavior is the same
And similar to your case as you remarked
@bearcatcrazy1971]
Yes, I agree with you, it’s not the battery, I’ve already swapped it, the problem is the firmware of the AC200MAX. Bluetti certainly knows that…
.
My system shows the same behavior as yours…
Thanks @BLUETTI_CARE ! Understood that the newer models do resolve that concern, and I do appreciate how Bluetti does try to accommodate systems with newer packs (eg 200Max supports B300K).
But, for those not updating after just 2 years of buying their expansion packs, I’m trying to understand this question since you offered to take suggestions
Assuming they’re calibrated, is it correct to say that expansion batteries shut down around 0% SOC? Ie won’t shut down around 20%.
If it is correct, is it possible (saying simplistically) to have FW add a special case, that does not discharge B230 expansion packs anymore once they reach <= ~5%? And they would only restart discharging when the main unit is also at ~5%. In other words, in this special case, an expansion battery’s drain is frozen, so that it doesn’t shut down, thereby retaining most of its capacity without manual intervention, and without needing a high-precision balanced discharge (which as you say is difficult)
Perhaps this is not physically possible given the B230 electronics and connection to 200Max or 200L, but my understanding is that there is an algorithm in 200L/200max that can shift which batteries power comes – the algorithm trying to maintain even discharge – so perhaps this is physically possible to add a “pre-shutdown freeze” for a specific battery pack’s power consumption when near 0% SOC.
Interested in your thoughts @BLUETTI_CARE, thanks!
Hi @bearcatcrazy1971 and @jCs, We completely understand your concerns. Upgrading to a newer model is merely a suggestion, as the advanced technology in newer models can address issues like SOC balancing more effectively.
If you choose not to upgrade, rest assured that the AC200MAX + B230 system can operate normally.
Under normal conditions, the system will not deplete one battery’s charge entirely before others. When in standby mode, the batteries will slowly balance their charge levels.
SOC will maintain a dynamic balance—relatively balanced rather than perfectly equal. From our perspective, an 11% SOC difference is acceptable.
The AC200MAX, released in 2021, utilizes the most advanced technology at that time. However, B230 batteries cannot receive firmware updates via the AC200MAX. Even if we wanted to optimize the charging algorithm via software updates, it’s not feasible due to hardware limitations.
We recommend testing the AC200MAX + B230 system as a whole to evaluate total capacity and runtime.
When the B230 reaches 0%, it will shut down automatically after 10 minutes, but this won’t cause the entire system to shut down. Note that the B230 requires a manual restart to begin charging again after shutting down.
To mitigate these inherent limitations, here are some battery maintenance tips:
Whenever possible, use a low current for slow charging instead of fast, high-current charging. A lower input current reduces internal resistance and heat dissipation, aiding in battery balancing and extending battery life.
Avoid deep discharges caused by inaccurate SOC measurements, as over-discharge can impact battery capacity and internal resistance. Begin charging when the SOC reaches 20%, rather than waiting for 0%.
Regularly fully charge the battery to recalibrate SOC for more accurate readings.
Thank you for your understanding, and please don’t hesitate to reach out for further assistance.
This does not work, the B230 batteries do not equalize their state of charge. How is this supposed to work, as there would have to be a charge equalization via the AC200MAX.
. They must mean the single-cell cells within the B230, yes, these are then adjusted via the BMS.
But the end user has no interest in that.
The manual restart charging process for the B230 batteries is no longer started automatically at 0%, at least the B230 batteries are no longer charged by the AC200Max. You have to charge
partly the B230 batteries with the external charger first.
This must not happen at all, a BMS must prevent deep or overcharging of the batteries. Normally, LF batteries are only discharged to 10% for safety reasons and charged to a maximum of 90%. Although the SOC display shows 0%, the batteries are certainly still at 10% charge.
I only have one B230 connected to my AC200max. Discharging with a heavy load such as a heater seems fairly even. But if I discharge more slowly, like ~100 watts of AC & 100 watts of DC, things get quite uneven until the B230 finally zeroed and shut itself off while the AC200 was still at 9%.
I took a few snapshots along the way:
AC200 max 37% standby B230 16% standby
AC200 max 26% standby B230 8% discharge
AC200 max 18% standby B230 2% discharge
AC200 max 10% standby B230 1% discharge
It is interesting to me that the AC200 read standby while it showed a higher charge. It seems like it did have been discharging while the B230 was on standby until they got closer in charge.
Also true to what others have noted, the B230 is not charging even though it’s connected and being charged with the grid. AC200 is up to 70%, but the B230 is at 1% and reads standby.
is it safe to think that we just have to bite the bullet and live with a system intended to make the users more annexes and always alerted as opposed to comfortable knowing there should be nothing to worry about?
Whilst i note you mentioned that AC200MAX is a “portable intended system” however the issues discussed here has nothing to do with how portable is the system! Have we made a mistake investing thousands of hard earned $$$ in this system?
On a positive note, i appreciate your responses to comments. On negative one, you seem to only explain the problem but no offer a fix.
Started to think that Ecoflow and other competitors come here on your forums and read these issue, and then go back and fix or build solutions to their hence they seem to have better market hold (at least what i think).
, especially if charging with solar.
