zennomind Posted July 15 Share Posted July 15 (edited) I assume that there is a problem with our Pylontech battery stack. There are no error messages on the inverter and the BMS has not thrown any error messages via the red light on the batteries. According to the Axpert IV inverter the string is pushing 400V at 1A and it is not varying much around those parameters. Here is some background to this system. I have two sets of panels (3.3 on the ground and 3.8Kwp on the roof) each connected to an Axpert IV and 4 x 3.5Kwh Pylontech stacks (labelled Turbo Energy and US3000C respectively). The roof system has always varied the voltage more than the amperage and the ground has varied both the voltage and the amperage. I swapped the inverter, the solar panels and all of the cables to see if the charging amperage could be changed. The charging remained as I described in the first paragraph. Additionally, both sets of panels, inverters and cables work as well as each other on the ground PV Pylontech battery stack. So I assume that there is a battery stack issue. In the roof mounted stack one battery has some corrosion around the earth terminal and in the communications ports which, to me, indicates a chemical leak, however, the voltages on each battery are the same (49.4V) and, as a lay person, I would imagine that that battery might not be charging as well as the other ones in the stack if there was a leak. I've attached an image of the corrosion. I don't have any hardware or software for reading the internal Pylontech states and I run Linux not Windows. I also don't have a LAN. So anything requiring Windows or a LAN are a non starter. Would the BMS be throttling the charging? Is there anything that can be done to get the battery charging properly? Edited July 15 by zennomind added an image of the battery label Quote Link to comment Share on other sites More sharing options...
GMAC Posted July 15 Share Posted July 15 Remove the suspect battery and see if there's a change . That corrosion does not look good . Best send the battery back to supplier for inspection . That lithium switch is off and dip switches are all off so that lithium must not in use . If all the batterys dip switch or all off position then can't think the stack was communicating with each othere so can only think the battery were out of balance Quote Link to comment Share on other sites More sharing options...
Tinbum Posted July 16 Share Posted July 16 On 2024/07/15 at 6:53 PM, GMAC said: If all the batterys dip switch or all off position then can't think the stack was communicating with each othere so can only think the battery were out of balance Have a read of the manual for dip switch settings. They only have to be on for very specific (not often required) uses. Quote Link to comment Share on other sites More sharing options...
GMAC Posted July 16 Share Posted July 16 My bad about dip switches . Best remove the battery you suspect is the bad battery and see what happens Quote Link to comment Share on other sites More sharing options...
zennomind Posted July 17 Author Share Posted July 17 @GMAC thanks for the useful tip about removing the suspect battery. After 20 something years working in software and often removing sections of code to see how the overall system changed that's something I should have considered. This says something about our ability to think laterally. Anyway, I removed this battery and the charging remained constricted. I removed battery 3 next, rebooted the inverter and the charging returned to what it should be i.e. not stuck on high voltage and low amps. So I charged the master and one slave to full capacity. Then I reattached batteries 3 and 4. Turned them back on and left them for a few minutes as there was some movement of charge between the fully charged and the last two batteries that were on about 40%. After that I turned the inverter on and the DC isolator. Surprisingly, the charging returned to normal! But the battery 4 charging light stuck at around 75% charge and so I switched the system off. I'll get the battery replaced. Dip switches: The master battery has 1000 for CAN communication with the Axpert IV inverter. The other three batteries are all on 0000 as shown in the photo. Both of my systems have been running with these settings for 2 years. Quote Link to comment Share on other sites More sharing options...
GMAC Posted July 17 Share Posted July 17 Happy you now finding the problem. I downloaded the Manuel and did then understand how the dip switches work on your battery's . These inverter work on percentage problems with that is the BMS can run out of calibration and so battery's can say be in reality half charged but BMS communicates fully charged to the inverter and this can also effect the balance between battery's . So best is to monitor each batterys volts over time as well with multimeter . I can name a number of good battery's that suffer from this issue . Even my battery stack percentage can very up to 15% between batterys over time and so I have to calibrate the stack but fortunately I see the volts between battery are all the same so the BMS's are keeping the stack balanced using volts not percentage but the inverters are using percentage from the master battery . Quote Link to comment Share on other sites More sharing options...
Tinbum Posted July 17 Share Posted July 17 I've not found my pylontechs ever out of balance. They measure the Wh going in and out which results in very good soc readings. Quote Link to comment Share on other sites More sharing options...
GMAC Posted July 17 Share Posted July 17 (edited) 26 minutes ago, Tinbum said: I've not found my pylontechs ever out of balance. They measure the Wh going in and out which results in very good soc readings. Interesting. Do you monitor your battery stack with RS232 cable or just using the soc lights as they can run out of calibration by 25% before you notice a difference . Some inverters do use volts and charges to full say 3.55 per cell every time it charges allowing the BMS to calibrate on every charge but reports soc by percentage . Othere inverters uses percentage and that were the BMS run out of calibration . The inverter will charge every time to 100% but with time the volts will keep dropping . I have seen BMS reporting 100% but battery's is flat . BMS update helps to fix some bugs but still battery runs out of calibration. My inverter at least allows me to set in a max charge volts in lithium mode very much like USE mode but does not float charge so my inverter never under or over charges Edited July 17 by GMAC Quote Link to comment Share on other sites More sharing options...
Tinbum Posted July 17 Share Posted July 17 14 minutes ago, GMAC said: Interesting. Do you monitor your battery stack with RS232 cable or just using the soc lights as they can run out of calibration by 25% before you notice a difference . Some inverters do use volts and charges to full say 3.55 per cell every time it charges allowing the BMS to calibrate on every charge but reports soc by percentage . Othere inverters uses percentage and that were the BMS run out of calibration . The inverter will charge every time to 100% but with time the volts will keep dropping . I have seen BMS reporting 100% but battery's is flat . BMS update helps to fix some bugs but still battery runs out of calibration. My inverter at least allows me to set in a max charge volts in lithium mode very much like USE mode but does not float charge so my inverter never under or over charges I use RS232 and an inverters measurement of SOC is rubbish. You can't measure SOC by voltage it's not accurate. I always use Battery /inverter communication and would never rely on the inverter to control things. Quote Link to comment Share on other sites More sharing options...
GMAC Posted July 18 Share Posted July 18 (edited) 12 hours ago, Tinbum said: I use RS232 and an inverters measurement of SOC is rubbish. You can't measure SOC by voltage it's not accurate. I always use Battery /inverter communication and would never rely on the inverter to control things. Agreed inverter measure of soc using volts never works and I never said I use volts to measure but I know of lots of people that still uses USE mode and do setups using volts, they prefer it so . With the inverter I have it has lithium mode and uses communication from the BMS for soc and can set all setting in % but can still controll the max volts charged with volts if you chose so . Edited July 18 by GMAC Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted July 18 Share Posted July 18 4 hours ago, GMAC said: Agreed inverter measure of soc using volts never works and I never said I use volts to measure but I know of lots of people that still uses USE mode and do setups using volts, they prefer it so . Some of us cannot use SOC and happy to use USE setting and use volts. It points to older inverters that are still running reliable. TaliaB 1 Quote Link to comment Share on other sites More sharing options...
GMAC Posted July 18 Share Posted July 18 (edited) 3 hours ago, Scorp007 said: Some of us cannot use SOC and happy to use USE setting and use volts. It points to older inverters that are still running reliable. Connected up to the flat on the property is my old MKS plus 3 kw inverter that is about 7 years old we running USE modes on lithium battery with out any issue for a few years now works great . And have installed a few lithiums at customer house that still have old inverter using USE mode and they the ones that so far have never complained about battery's running flat but show +-50% and system shutting down Edited July 18 by GMAC TaliaB 1 Quote Link to comment Share on other sites More sharing options...
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