Hi. Recently my pylontech batteries seem to stop charging at around 90-93% even though there is solar power available. I have 3x 3.5kWh pylontech batteries, Multiplus II and a Cerbo GX running an ESS system. Not sure whether this is due to the cold weather. I have made a short video to show what is happening on the VRM monitor...
CHeers. Tom, UK
Tom, I do not have an answer but I am having something similar in that my Pylontech 3.5kWh x6 will consistently stop at 89%. Unlike you, it is still drawing power from solar. It will stay at 89% from between 30-45mins and then suddenly jump to 92-95% and work as normal. During the 89% period I have no idea where the energy is going but it does not look like it is going to the battery and neither the grid. I have Grid feed-in enabled.
I realise it does not answer your question but maybe they are similar issues and some other experts may have an answer.IMG_1433.PNG
Hi Tom,
Not sure if I can add much, but I will try.
I also have Pylontech batteries (US5000) and when they get to 90-95% charged they only slowly charge to 100% (this happened on me today, and eventually they charged completely upto 100%). I am sure that I have read somewhere that the charging ramps down as the batteries get closer to full charge.
It might just be a time thing that you have to wait and they will slowly charge to full capacity, rather than expecting them to use all of the available PV power to charge them.
Hope this makes sense.
Graham.
Today (16-Jan-2024) and Yesterday I too experienced similar symptoms as OP.
I have 4x Pylontech US3000C with a Solis inverter.
Both days have been sunny all day however the batteries filled to 89% SOC and then no further, whilst the extra PV seemed to be 'lost', it was not being exported to the grid.
I found this blog post describing how Pylontech batteries react to ambient temperatures whilst researching the symptoms I just described and thought it might also be of benefit to other readers here.
Ref: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom
Pylontech's BMS will restrict the Charge Current Limit of the battery in cold weather. The precise temperatures and limits are not published by Pylontech, but anecdotally from reports it would appear that batteries begin to be limited below 18 degree C, severely limited below 10 degrees C, and completely restricted from charging below 2 degrees C.
Having read the above, looking at my history tracking for the batteries cell temperatures today, they ranged from 7.8C, rising to a maximum of 12.6C
So, it would seem it is probable that the reason my inverter and batteries acted strangely yesterday and today (ie they didn't charge as much as I was expecting) is 'working as designed' after all.
Although I have had the batteries/inverter for nearly 3 years I have only recently been looking closely at their behaviour as I am now automating changing the inverter settings to force charge the batteries at different times in the day based on my electricity tariff having different price bands. Chances are it has always been this way and I have only now noticed!
There is no secret about temperature limits on the Pylontech batteries.
Those information can be obtained from each type of battery through battery's console port.
On my US2000C batteries, the temperatures reported by battery are:
MOT (maximum over temperature): 90*C
MOTR (maximum over temperature recovery): 80*C
OT (over temperature): 60*C
OTR (over temperature recovery): 55*C
HT (high temperature): 50*C
HTR (high temperature recovery): 45*C
LTR (low temperature recovery): 0*C
LT (low temperature): -5*C
UTR (under temperature recovery): -5*C
UT (under temperature): -10*C
So the battery will behave normally between 0*C and 45*C.
In the same way you can find out that, for example, US2000C, the "start to balance" voltage is 3.36V and the "balance current" is set to 30mA.
Use any serial terminal program like Realterm on console port of the battery and find all of the above using "config" command.
If you have a GX device in the system and the Pylontechs are connected to it, there's a lot of information available from VRM.
With the custom widgets in the advanced section you can plot things like SOC, CCL, battery temperature. Most of the Pylontech data is to be found under battery monitor.
@Kermadec @Taddy @dipster25 Temp aside, Pylontech batteries balances at approximately 89% and the time it takes varies. There after it progesses fast. Sitting at 89% for 20min on my 6 x US3000 is not unusual and can be confused with "not charging".
@ejrossouw @Kermadec @Taddy @kevgermany Thank you for your replies and it is reassuring to know the US3000c’s are working as designed. A little frustrating as my system takes up to an hour to spring back into life. It will jump from 89% to 95%. I guess my issue is with the lost PV energy that is not 100% going into the battery, the grid or being used. The last few days in the UK it has been pretty sunny and during the hour it was at 89% PV was generating 3kWh+. I have 6xUS3000c, the 89-95% is roughly 1kWh. Well, at least I now know there are no faults in the system. Thanks again
That 90% zone is the place where the BMS decides to switch from C/2 to C/5 current.
Probably it's a "end bulk, begin absorption" zone.
You can also graph the CCL together with the Voltage and Amps and you'll see the CCL change around that 90% SOC during both charging an discharging process.
Just by looking at highest and lowest cell voltage on battery details.
If the difference is lower than 30mV, it means that all cells from all batteries are balanced and none of the balancers are active. Greater than 30mV, on the same battery, means at least one balancer is active.
You can also see the individual cells balancers if they are active or not, but, again, it will mean to connect to the console port of the battery.
Make or buy a simple serial cable like the one below and then use monitor software or a plain and simple serial terminal.
https://powerforum.co.za/topic/8532-how-read-data-from-pylontech-us2000c-console-port-to-pc/
I use such a serial cable, connected between the master battery and an esp8266. The esp8266 sends some metrics to MQTT but also provides an HTTP web interface to allow commands to be sent to the batteries. I then have a Node-Red flow which polls the web interface to issue a couple of commands and parse the output, feed into a mariadb database and plot with Grafana:
I was not aware of how 'Balancing' works so these this discussion has been really helpful, thank you to all contributions.
Checking the Pylontech battery CLI the 'bat' command outputs a column entitled 'BAL'... I guess that is 'Balance' ?
Had not noticed this before so I will now parse that as well and add to the Grafana charts to indicate when the batteries/cells are balancing. :-)
Yes, that BAL column tells you if that cell is balancing (Y) or not (N).
And you can also use the "config" command to get the voltages, currents, temperatures, etc that are configured inside battery.
You will see there that the start balancing voltage is at about 3.36V, with 30mA. Sloooow.....
Hi @Kermadec ,
It seems that you graphed the same battery, the first battery.
Probably you've used just "bat" command.
Use "bat 1", "bat 2", "bat 3", "bat 4" for each battery.
Most of the commands support index to specify which battery the info belongs to.
Thank you for calling that out.
I have checked my code and indeed I do use the battery number with the 'bat' command as you highlight. I am parsing the 'BAL' field from the same 'bat' output as parsing the other fields (Curr, Tempr, SOC, etc) per battery.
I do agree that the charts appear identical which does feel a bit odd, but I am no expert on this subject.
I have increased the frequency of my data collections to see if that helps expose what might be going on.
https://github.com/irekzielinski/Pylontech-Battery-Monitoring
This is the project, including cable pin-out, esp8266 details, and code... to give a web interface for your pylontech batteries.
As a side comment if you are running ESS with battery life you will see the ESS state change for anything under 17°C you will see ESS#5
