I have had a problem with “Battery Monitor [512], High voltage alarm: Alarm” every day for over 2 months now.
The High Voltage Alarm appears around 7-times in a row every day after the battery is charged over 96%.
Investigation + Asking for help
The company that installed my solar system & batteries is no longer specialising in solar systems, so they are not able to guide me through. Luckily Darcy, former employee of the company, who performed the installation, tried to fix the problem and provided me with following advise:
Darcy set the maximum charge voltage to 52V on 10 Jul 2026, but it did not resolved the problem, just lowered the number of High voltage alarms per day from like 8 to 6.
Firmware upgrades may be needed and the specific sequential firmware versions may need to be updated in certain order.
Solution that should fix the problem
At this stage I ordered 2 more Pylontech US3000C battery modules (Pylontech LV US3000C 48V 3.55kWh LiFePO4 Battery Module). I should have an electrician coming to install them and balance them once they arrive.
The batteries were installed in July 2022, meaning they are 4 years operational. My understanding is that their capacitylowered down a bit and as they were undersized for the Quattro 48/10000/140-100/100 the problem started to appear now.
Questions
Q1.) Providing extra 2 battery modules should fix the problem, am I right?
Q2.) I’m about to buy “Victron Interface MK3-USB”, is there something similar for Pylontech? … I read somewhere that USB to RJ45/RJ11 serial console cable might be enough.
1x IP20 / 22RU Floor Mounted Cabinet(Fits up to: Pylontech US2000 x 10, UP2500 x 9, US3000 x 8 + LV-HUB x 1)
1x Victron Quattro 48/10000/140-100/100 230V VE.Bus
1x Fronius 8.2kW Single Phase PRIMO Solar Inverter Dual MPPT IP65 AC With WIFI
1xVictron Color Control GX
1x Noark MCCB 400A 750VDC 3 pole (Bigger battery isolator)
20 Trina 500w mono vertex panel
History of my High voltage alarm problem
First time the alarm appeared on 27 Mar 2024. Since then it appeared occasionally with long time spans (a couple of months, half a year or so).
From 12 June 2026 it happens every day.
There was a full day overcast on 11 June 2026 and the battery level lowered down to 25% next morning, which was the lowest value for the whole time owning the Pylontech battery modules.
Calculation of the Minimum battery sizing per Inverter / Charger Model
The section Minimum Battery Sizing Recommendations provides an example for the US2000 (2.4 kWh) battery modules. The battery modules I have are US3000C (3.5 kWh), which are much stronger (+1.1kWh).
I made some approximations based on US2000 and researched the formula for the number / type of batteries (see the details below). The Quattro 48/10000/140-100/100 requires a minimum of 5 US3000C battery modules. Meaning I’m oneUS3000C battery module short (I currently have 4, but I rather ordered 2 more).
Approximation
Minimum Battery Sizing Recommendations for US2000 with Quattro 48/10000/140-100/100 are 7 modules.
US2000 has 2.4kWh
7 * 2.4 kWh = 16.8kWh
US3000C has 3.5 kWh (Usable capacity of 3.37kWh @ 48 VDC)
4 * 3.5 kWh = 14 kWh
5 * 3.5 kWh = 17.5 kWh
So by approximation there’s a need for 5x US3000C.
Research
Quattro 48/10000/140-100/100 has a maximum continuous output of 8,000W at 25°C.
To prevent the internal Battery Management System (BMS) from shutting down under full continuous load, the battery bank must be able to match or exceed the inverter’s 8,000W capability. I assume similar applies for charging.
Each Pylontech US3000C has a recommended continuous charge/discharge rating of 37A (approx. 1,776W at 48V).
Dividing 8,000W (Quattro inverter charger) by 1,776W yields roughly 4.5 modules meaning 5 modules.
You would have a better outcome on the Victron-Pylontech integration with a Cerbo or Ekrano - the CCGX won’t go past 3.55 and somewhere around 3.70 the GX devices gained the ability to update the Pylontech firmware remotely and do some nicer things with DVCC.
The Pylontech serial console cable is RS232 and is easy enough to obtain. Their BatteryView tool only runs on Windows. The firmware update is reasonably straightforward, but you will need the right firmware for the batteries you have. If your batteries are all from the same “batch” you will be in good shape, otherwise you might require several firmware files to update.
Your batteries have started to progressively age and developed cells with high internal resistance.
Those are getting first at the high voltage threshold and trigger the high voltage alarms.
Don’t want to alarm you but slowly, in the future, will also be overvoltage alarms and Pylontech technical department, if you apply for warranty at some point, will want first to see the event logs from batteries and have their eyebrows raised when they’ll see so much high voltage alarms.
For Pylontech batteries, the lowest for 100% SOC is 52.2V, but you already have it at 52V.
You could try to lower it further, to 51.75V, which, after the current is settling down, it’s about 97% SOC.
Don’t worry about balancing, that is starting as soon as one of your cells is over 3.36V and deltaV is above 30mV.
So the packs will balance, even at 51V.
But this is a solution for masking a problem, not solving it.
If you have good technical skills and the batteries are out of warranty, I would sacrifice one battery to take from that good cells with low internal resistance and replace bad cells with high internal resistance from the other ones.
The Ekrano is nice, and if your Color Control GX is in the wallbox, a nice designer from Victron has made it so the screw mount positions are the same spacing.
The Ekrano and wallbox are slightly bigger (so if your CCGX is mounted very close to other things, you might need to rearrange).
The connections on the back are identical (VE.Direct, BMS CAN etc), but rather than push-in power ferrules, the Ekrano has a nice connector (which the same ferrules from the CCGX power can be pushed into). Same deal for the two-wire generator autostart if you are using it.
The Ekrano solution for updating the Pylontechs would still need the firmware files for the batteries, and as I mentioned, there is different firmware for different battery serial numbers.
The Pylontech console cables are cheap and probably worth having one anyway.
Reading what you wrote I’m planning to get in contact with the Pylontech technical department to keep them in loop so they can check the plethora of high voltage alarms and hopefully give me some advice.
Do you know what’s the best way to contact the Pylontech technical department?
I think I’ll start with an email, wait a few days and give them a call.
I have a 10 year replacement warranty on the 4x Pylontech US3000C battery modules and they are in use for slightly over 4 years.
Do you know what information you need to apply for a warranty?
I’ve read that for warranty submission are required serial numbers, logs, and proof of purchase.
The batteries registration might be also required: Pylon Technologies Co. (I have to find out if the installer registered the batteries or maybe I should do it now).
I followed your advice and lowered from 52V to 51.7V (not having an option for 51.75V). I’ll see if it improves the situation.
We came across a 2000C with the same issue recently, from 90-100%, in the master MP2 it was set to 52V and also in DVCC from the Cerbo.
In VRM we made a highest and lowest cell graph and we could see that it was 0104, meaning cell group 1 from battery 4, there one cell was lower and one cell was higher with 120mV difference.
Above 50.40V a pylontech starts equalizing with it’s BMS, we have set the DVCC and the master MP2 to 51V so the low cell is still equalised and the high cell stays below high voltage, with a difference of only 30mV now, in that way it will probably work for years to come.
All data were send to Pylontech, Pylontech is sending a new one as we speak, it’s very difficult and can take months before a reaction comes as officially the vendor should be contacted first to make an RMA.
One thing one colleague of me said is that you must see if your Fronius has the latest firmware, this as with previous firmwares there were issues that the Fronius was not reducing fast enough and so the Victron inverter had no option then to overcharge the battery…
There are several topics here where you can read that issue with Fronius and how to solve that.
Update Firmware Download and install the latest firmware for your Fronius inverter via the Fronius Solar.web portal.
Reload Country Setup Reload the country setup to MG50.
Adjust PROFI Settings, Access the PROFI menu on the Fronius inverter.
Press the third button from the left on the inverter display five times until “00000” appears.
Enter the code 77634 and press Enter.
Then navigate to: a. Normal Power Change Gr.
b. Set UpRamp and DownRamp to ON.
c. Adjust both the UpRamp Gradient and DownRamp Gradient to a value below 1%/sec (e.g. 0.90 %/sec).
The 0.9%, can be to low, we use normally 4% up and 10-20% down, the higher down, the lesser change to over voltage on your batteries.
I contacted Pylontech support on service@pylontech.au and they replied very quickly.
I received instructions from them on how to export both “history” and “event” logs (in TXT Format) to send them back. They provided me with necessary software, firmware and manuals. Unfortunately BatteryView software is working only on Windows (I’m more of a Linux person).
They also confirmed registration of my batteries (performed by installer) based on serial numbers and informed me about my Warranty Expiration Date: 2032-04-30.
I ordered the Pylontech console cable as well as the Victron Interface MK3-USB, so I should be able to access both Pylontech and Victron devices. I’ll progress things forward once I receive the cables.
My Fronius Primo is way behind the latest firmware
I’ve learnt how to update my Fronius Primo either by USB flash disk, by mobile application (Fronius Solar.start App) or by website (Fronius Solar.web).
It should be possible to revert back to the previous firmware of Fronius Primo according to this video: https://youtu.be/CxdJ0N0aRbo?si=-2pRozq4s7WSRl3C , but I do NOT see such an option with my Fronius Primo.
It might be available after the new firmware is installed, but I’m NOT sure if I want to risk it.
I will contact Fronius technical support to ask them for the older firmware version my inverter is using now (only the latest firmware file is available online).
I’ve understood that to be safe with every firmware update (Pylontech US3000C, Fronius Primo, Victron Quattro) I should have current firmware file (firmware in use before update) to be able to revert back in case of incompatibilities.
I checked the VRM Graph you’ve mentioned: “BMS Min/Max Cell Voltage” and I can see for today that one cell was lower and one cell was higher with 270mV difference (see the screenshot attached). I checked the past few weeks and I could see even bigger differences (probably before I lowered the maximum charge voltage).
In my “BMS Min/Max Cell Voltage” graph I do NOT see the Min/Max voltage cell ID. I checked the Victron Color Control GX and it has information about real-time Lowest cell voltage and Highest cell voltage including cell IDs.
I’ll check the Lowest cell voltage and Highest cell voltage with their cell IDs tomorrow when I get the High Voltage alarm again.
If it’s over 3.65V for a few seconds it will throw an over voltage alarm - worse than high voltage - , it will block the charging and it will lit the red error led.
It will only recover if the voltage of that cell will go down below 3.5V.
This is how the Pylontech BMSes are configured and this is why you see that “oscillating” voltage on the high voltage cell.
If you try to discharge the battery normally down to, say, 10%, you’ll see an even strange behavior, where the min and max cells are drifting apart from one another with deltaV voltages towards 100mV, even if the general curve is showing the normal shape.
Something like this below, a discharge to about 45%. You can see the first lithiation stage with the first drop at around 70%.
Again, this because the high internal resistance cell(s) are dropping the voltage much aggressively than the normal ones. Also seen on the graph, when various higher loads are present, where on the high cell curve the drops as small and on the low voltage cell the drops are 2-3 times bigger.
I would disconnect all batteries and leave only the master, then check the high and low of the master, if ok, then put one slave (set as master) and see the high and low again, etc.
This as a GX device only shows the high and low from all batteries together, and seen this 270mV (very very high difference), there might be other cells in other batteries which are almost at that same point.
When you then have that data (screen shots), send it to your vendor to make an RMA.
Did you lower the charge voltage to 51V, to see if that lowers the high cell?
It might then only charge all batteries to 95-97% only, but at least it might stay on without alarms.
