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henrij avatar image
henrij asked

Why Pylontech Batteries only reach 97% SOC

After the upgrade of Venus GX to v2.20 software, everything worked fine. The daily usage pattern is largely the same when I noticed Pylontech batteries (4xUS2000B) only reach 97% SOC (originally 100%) with plenty PV capacity available. Matthijs kindly advised that the end/of/charge voltage was lowered to fix an occasional over voltage shutdown from the Pylons and they are discussing various things with Pylon R&D though perhaps with some changes on both sides. Are there any planned changes envisaged or recommendations readily available? Charger is a SmartSolar MPPT 250/100.

Venus GX - VGXSOC
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power4all avatar image
power4all answered ·

Are they still around? No updates on their website and no social media movement. Cannot get response on emails. Nobody want to give you support on their products. Bought a dud battery 3.5kw and nobody want to help.

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nismoboy34 avatar image nismoboy34 commented ·

@Power4All sounds like the experiences i have been having alot with the products from That geographical location .... sad to say but it looks like alot of the time customer satisfaction is low on the list .. not to mention the language barrier.. Maybe post your question and we can try and assist .

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Henrij,

As you mentioned there was a change made in Victron programming to reduce maximum charge voltage to improve reliability, explained here -

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom#my_system_only_charges_the_battery_to_52v

It is possible for the batteries to reach 100% with this new charge profile, But less certain for it to happen.

I don’t expect any change in firmware from Pylontech to report SOC differently. Though if it happens, we will update that FAQ.

I understand the want to see a full battery at 100%, but the meaningful difference in usable capacity is extremely small and worth the improved reliability from Victron’s perspective.

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Jesus Mazo avatar image Jesus Mazo commented ·

Hi Guy. We have got the same issue on a system comprised with 16x US3000 batteries and 3x10kVA (230V) Quattros forming a 400V system. After cicling several times we have proven that it never reaches 100%. This is a problem for us as our application in hybridization of diesel generators and therefore we do not know when to send the signal to the generator to switch off.

I understand that Victron wants to inprove reliability but Charge Voltage limit reported by the pylontech BMS is 53.2V, however as soon as the dvcc is set up the absortion voltage is set to only 52V. The result is that is never reaches 100%, it charge really slowly above 90% and we lose available capacity, this might no be a problem on small home solar installation but it is on industrial hybrid applications. From my point on view, the DVCC is extremely restrictive and force the user to disable it to set up the absortion voltage to 53.2 as it should be according with Pylontech recommendations.

Is this something that could be reviewed by Victron on future GX software updates? there are other leads on the community from people complaining about it.

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dayandnight avatar image dayandnight Jesus Mazo commented ·

Hello @Jesus Mazo,

I run an ESS, 3 phase Multiplus-II 3000 with eight Pylontech US2000B and a grid based PV. My system reaches without problems every day 100% SOC. I use a relay assistant at 100 % SOC to control my PV-system. And it works like a charm. I use as Absorbtion voltage instead 52,0 V a lower value of 51,6V - because this lower voltage was recommend in some threads here.

But be honest, I don't understand how the absorbtion voltage influence the maximum SOC level. I tried to find out how much energy is really in the batteries at 100% SOC, which is not easy to check. As far as I could "recalculate" used energy I think 100% SOC is in my case +/- something correct.

DayAndNight

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ Jesus Mazo commented ·

Hi @Jesus Mazo,

The more batteries that you have, the longer it will take, and less likely it will be that they regularly reach 100%.

Pushing the battery closer to the reported 100% state more quickly, and more often with a higher battery voltage is only more likely to cause a battery/system shutdown at some point as some of the cells in the bank will be higher than others, and then trigger overcharge thresholds. With a larger battery there is more chance of imbalance due to wiring and resistance variations between the blocks of cells.

It is now forbidden to disable DVCC to try and push the batteries further (outside of the tested parameters) beyond what has been tested by Victron and Pylontech.

These current settings are based on many thousands of real world systems, and our testing, compatibility and engineering partnership program with Pylontech is now over 4 years old.

It's an ongoing program that is continually reviewed based on customer faults, system warnings, firmware changes, and hardware revisions.

Victron works directly with Pylontech engineers, and the parameters set by DVCC are the Pylontech recommended settings when using Victron equipment. Attempting to modify those will not improve overall system performance or reliability in the long run.

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Jesus Mazo avatar image Jesus Mazo Guy Stewart (Victron Community Manager) ♦♦ commented ·

Thanks Guy for your quick reply. I really appreciate it.


I am trying to understand whether or not a system with 16xUS3000 is ever going to reach 100%, if so, get some kind of idea when is this going to be possible, ¿after 2, 5, 10 or 50 cycles...? otherwise, if there is no clear answer for when it would reach 100%, how can I program the logic to start and stop the generator every charge cycle (we use an external controller and not the GX for remote start/stop signal, our standard setting is that we switch off the generator 5 minutes after reaching 100% SOC).

I have started using pylontech but have got a lot of experience with similar systems using BYD and never had this issue before. Why is this the case with Pylon? Reading the explanation for why it is set up to 42V to improve reliability, does this mean that pylontech batteries have not been reliable before?

Thanks in advance for your comments.



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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ Jesus Mazo commented ·

Yes, a 16 battery system will reach 100%. But maybe not your system if you are only charging with a generator (and stop it from running continuously at virtually no load to do the final trickle/balancing charge). It is not just a factor of how many cycles, though that will help bring all the cells into closer alignment.

Another way to think about it is what is the total time the batteries have spent collectively at that balancing charge voltage. The meaningful/useful charging of the batteries is over, now it's just the final extremely low current stage to fill them to the very top.

Think of it as filling the generator with fuel, you can POUR in the fuel to get it 95% full, but to get the fuel tank to 100% of it's maximum, you must go a lot slower to prevent overfilling it and spilling out the top.

It is exactly the same for the battery. You might spend as much time CAREFULLY going from 99% to 99.5% of the fuel tank as you spent getting from 80% to 90% full pouring in at full speed.


As a place to start, try setting your generator to consider the system as full at 96% on the daily cycle, and then run a balancing cycle to 99% once a month (this will likely be very long run time).

Even better would be the addition of an MPPT connected to solar, as this will happily trickle power in all day (without wasting fuel on a nearly idling generator). Then use the generator for the bulk charging stage (monitoring the system in VRM can help identify the most efficient window and refinement of the settings.).

It can be difficult to accept, because we all love to see 100% - but as long as it is in the high 9x%, from Victron and Pylontech's perspective the system is absolutely fine, charging and operating normally.


Regarding reliability, and improvements to it.

The diplomatic answer is nothing is 100% reliable. The best that can be done for any power electronic product from any company is that there is continuous efforts and developments to refine the experience for as many use cases, and as many climates, conditions and markets as possible. With ongoing improvements made by all parties involved.

There have also been adjustments made over the years to our DVCC parameters for BYD and all other compatible battery partners.


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justin-adan answered ·

While I understand all of the above, my system seems to now not push the batteries over 90% ever, even with plenty of Sun to top them up once they reach 90%. They were happily charging and operating to 100% until a recent update so pretty bleak to lose 10% of the capacity of my bank just for safety.

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