I’ve been reading a lot of posts here about the “High Voltage Alarm” problem. I just can’t interpret the findings for my own situation.
I have an east-west-facing PV system with 4.6 kW of generator capacity, 3 APsystems DS3 units and a QS-1200. I’m using a Victron MP2 3000 and five Pylontech US2000 batteries from 2022 and 2023, with an SoH of 97%.
For some time now, I’ve noticed that the charging current starts to drop quite early, sometimes at 89%.
The charge termination voltage is set to 52.1 V.
A few years ago, I already had a warranty case involving swollen cells, which Effekta resolved by replacing the battery. Is it possible that the same scenario is happening again?
I can only interpret the battery monitor as a layperson, but I suspect there is a significant difference in the voltage readings.
The batteries from 2022 in particular seem to be susceptible to this.
Take a closer look at the batteries to check whether there are any bulges at the rear.
Set the system to “Keep battery charged” for 1–2 days so you can reach 100% and the cells can balance themselves.
Thanks, I’ll take a look at that tomorrow in daylight.
The three US2000Cs have one fewer LED on the charge-level indicator. Is there a reason for that?
0104 and 0105 should, as far as I know, be the two older batteries. The minimum and maximum voltage are also measured in those.
I think it’s normal for the individual modules to show “different” SoC levels. At least, I’ve been observing this very clearly (via my own Com-Cable readout) right from the beginning.
Sometimes there is up to a 15% difference between the modules. At 90% and 9%, however, the BMS stops reporting the SoC, and the SoC levels stagnate until the cells reach a certain “voltage threshold”. All the modules then reach that threshold at roughly the same time—and ultimately appear to be “equally full” after all.
Only Pylontech probably knows why the individual modules (even those of the same type) show such different SoC levels between 9% and 90%.
I would use a higher charging voltage; 51.2 V is borderline low for cell balancing. Pylontech says that balancing starts at 3.36 V, but at 51.2 V that works out to just 3.41 V if the cells are perfectly balanced.
You can safely give them 52.4 V (= 3.5 V); the “new” Pylontech BMS still keeps requesting 52.8 V (via CVL).
Cell balancing starts to occur already at 50.40V (+0.07V in practise), therefore you see at 89% with a “problem cell”, that it keeps that voltage for 5-30 minutes (and even longer, check DVCC charge limits at that time), to give these higher cells time to come down.
But, I do not see a high cell in your system…that’s indeed the strange part, well, that indicates for me that from one (or more) of the batteries the BMS is malfunctioning and not correctly responding anymore.
What you can do; first lower to 51.00V maximum charge, let it run a day or 2, hopefully no alarms, raise per day 0.15-0.20V and see again, your charge % might be lower (94-97%) and/or it takes a long time to get to 100%, till you get that alarm again, then lower the last setting back.
Also, the master of the batteries gives you a state of health of all batteries together, which you can make visible in VRM, and which you can also read from the GX, check it…below an example of the same with a stubborn cell.
Thank you for the detailed information. Since I’m not an expert in this area, both approaches sound plausible based on the reasoning.
I can try them one after the other.
I had exactly two alarms in September. It’s not constantly in high-voltage alarm mode.
There should be plenty of sunshine tomorrow. I’ve added the SoH to the reports. How can I break this down for each individual battery? Is that even possible?
Tomorrow, as Matthias wrote, I’ll inspect the batteries from the outside to check whether any cells are swelling again. The min. and max. voltage readings were in battery no. 5 earlier. That one is from 2022.
So I’m trying things out and will get back to you if I notice any changes.
Thanks and best regards.
Ingo
Is this from your phone or computer, if it is your phone, turn it horizontal, pending the screen size as well btw, then right hand side you should be able to these numbers…
On a computer you see them normally instantly.
But, if all not working, check with remote console, go to the pylontechs, search a bit, and you can see the min/max cell voltage and the cell pack and module as well…
Via the CAN bus protocol, the BMS only sends the min/max voltages to the GX.
You can only get all the cell and module values through the console port using an RS232 reader and a script to process them.
Seems to be as dognose says. What hardware is needed for this, and where does everything get connected? These may be basic things that I unfortunately don’t know.
The GX’s USB ports are already occupied. A hub?
However, I think we’ve now identified the problem. Battery 5 is swelling.
We can see the rear lower support rail. The left and centre are fine, while on the right there is a gap of up to 3 mm.
It’s probably not bad enough yet to trigger alarms constantly, but the process is under way and is similar to the case 2 to 3 years ago, when one of the batteries in the Effekta series was replaced under warranty.
Actually, you can also set higher voltages. The MP2, or rather the controller running Venus OS, limits the charging voltage anyway so that the maximum cell voltage does not exceed 3.5 V. Unfortunately, this also means that it can take weeks for the SOC to jump back to 100%.
I’ve now removed the fifth module, and the problem seems to have been resolved. It now charges fully again instead of stopping at 88 or 92 per cent.
I’ve actually been getting on very well with a charge cutoff of 52.1 V for years. Forcing in those last few extra watts probably isn’t good for the LiFePO₄ cells. The faulty battery is a US2000B+. The casing is distorted and the cell(s) have swollen.
My helpful seller is dealing with the warranty claim with Effekta. That leaves me with just one battery from the 12/03/2021 series.
