molesza Posted August 30, 2022 Share Posted August 30, 2022 Hi I have just had my solar system installed. Victron system with Freedomwon 10/8 battery. The batteries are set to keep charge at 100% so that it only gets used during loadshedding. I would expect the battery to stay at 100% when fully charged and idle there. However, it is constantly charging and discharging. It will discharge to 99% and then charge up to 100%. It will charge for 15 seconds, then discharge for 15. Is this because the BMS system is trying to balance the cells? Is this normal for a new install? Quote Link to comment Share on other sites More sharing options...
mzezman Posted August 30, 2022 Share Posted August 30, 2022 I am assuming you have solar panels as well? Generally Lithium batteries don't like being at 100% all the time - unlike Gel. It might be worth setting up a schedule to use them then recharge using the panels - basically some form of cycling for the batteries - this would also start to payback your investment in the system by reducing reliance on Eskom MakoShark 1 Quote Link to comment Share on other sites More sharing options...
molesza Posted August 30, 2022 Author Share Posted August 30, 2022 2 minutes ago, mzezman said: I am assuming you have solar panels as well? Generally Lithium batteries don't like being at 100% all the time - unlike Gel. It might be worth setting up a schedule to use them then recharge using the panels - basically some form of cycling for the batteries - this would also start to payback your investment in the system by reducing reliance on Eskom Thanks for the reply. Yes I have panels too. I really want to have as much possible for power failures as we often have full days without electricity. So I should expect the batteries to do this constantly? Quote Link to comment Share on other sites More sharing options...
Bobster. Posted August 30, 2022 Share Posted August 30, 2022 (edited) 48 minutes ago, molesza said: Hi I have just had my solar system installed. Victron system with Freedomwon 10/8 battery. The batteries are set to keep charge at 100% so that it only gets used during loadshedding. I would expect the battery to stay at 100% when fully charged and idle there. However, it is constantly charging and discharging. It will discharge to 99% and then charge up to 100%. It will charge for 15 seconds, then discharge for 15. Is this because the BMS system is trying to balance the cells? Is this normal for a new install? My 10/8 shows similar behaviour when the battery is fully charged. The difference between our two scenarios is that I draw from battery overnight, with a limit set so that the battery may not go below 40% charged whilst grid power is present. The only problem scenario here is a prolonged outage coupled with overcast weather. Most days the battery discharges to around 45% left over night and into the early morning, then the PV starts coming in and recharges the battery. Just a thing to point out: Probably your property has been split into essential and non-essential loads. Only the essentials will draw from the batteries during an outage. In my case this means no guest geyser (our main geyser is warmed by a heat pump) and no swimming pool pump. We have full gas cooking. Assuming this split has been done for your property, how much are the ESSENTIAL circuits going to need for a full day with no PV incoming? Edited August 30, 2022 by Bobster. add point about DB split system32 1 Quote Link to comment Share on other sites More sharing options...
molesza Posted September 21, 2022 Author Share Posted September 21, 2022 (edited) So its been a few weeks now and not once has my battery reached float stage. I have set my system to keep batteries charged to 100% because of our current load shedding. Load shedding is giving my battery plenty of exercise. I am still seeing that the battery jumps between 98% and 100%. I am also seeing quite a difference between low and high cell voltages. I'm really not sure that this is default behaviour. My system can be viewed on VRM world at - https://vrm.victronenergy.com/installation/207352/share/e5b174b9 Freedomwon batteries should be float charge at 55.8v My batteries have never reached that voltage. Edited September 21, 2022 by molesza Quote Link to comment Share on other sites More sharing options...
Bobster. Posted September 22, 2022 Share Posted September 22, 2022 The inverter never stops inverting. Even when you have configured your system to maintain SOC=100%, the backed up side is constantly pulling through an inverter. So the battery is actually being used all the time. The difference between your scenario and mine, is that I let the battery discharge down to 40% SOC remaining when grid power is present, whilst you want it at 100% all the time. That's fine, we have different requirements, but your system is essentially constantly discharging on one "side" whilst charging at the other. And the inverter will take instructions ("charge now", "stop charging" etc) from the BMS. My 10/8 shows the same behaviour when fully charged, constantly fluctuating between 99 and 100%. Maximum voltage on my system, as set by the BMS, not by me, is 55.5V. I don't think it matters what voltage the inverter "sees", the BMS runs the show. BryanOC6 1 Quote Link to comment Share on other sites More sharing options...
molesza Posted November 13, 2022 Author Share Posted November 13, 2022 On 2022/09/22 at 12:21 PM, Bobster. said: The inverter never stops inverting. Even when you have configured your system to maintain SOC=100%, the backed up side is constantly pulling through an inverter. So the battery is actually being used all the time. The difference between your scenario and mine, is that I let the battery discharge down to 40% SOC remaining when grid power is present, whilst you want it at 100% all the time. That's fine, we have different requirements, but your system is essentially constantly discharging on one "side" whilst charging at the other. And the inverter will take instructions ("charge now", "stop charging" etc) from the BMS. My 10/8 shows the same behaviour when fully charged, constantly fluctuating between 99 and 100%. Maximum voltage on my system, as set by the BMS, not by me, is 55.5V. I don't think it matters what voltage the inverter "sees", the BMS runs the show. Thanks for your reply. I have only just seen it today. I feel confident now after your explanation of the battery being used by the inverter constantly. Thank you. You mention that 55.5v is the maximum voltage set by the freedom won BMS. From the freedom won manual it says to have float charge set to 55.8 via VE Configure victron app. This is what was set by the installers. Is this overridden by the Freedom Won BMS? Thanks for your time! Quote Link to comment Share on other sites More sharing options...
Bobster. Posted November 13, 2022 Share Posted November 13, 2022 1 hour ago, molesza said: You mention that 55.5v is the maximum voltage set by the freedom won BMS. From the freedom won manual it says to have float charge set to 55.8 via VE Configure victron app. This is what was set by the installers. Is this overridden by the Freedom Won BMS? A typo on my part. I just checked again and vmax is set to 55.8. This is not a setting I can manipulate, so it was set by the BMS. Quote Link to comment Share on other sites More sharing options...
molesza Posted November 14, 2022 Author Share Posted November 14, 2022 13 hours ago, Bobster. said: A typo on my part. I just checked again and vmax is set to 55.8. This is not a setting I can manipulate, so it was set by the BMS. Thanks for getting back to me Bobster Quote Link to comment Share on other sites More sharing options...
0012 Posted November 14, 2022 Share Posted November 14, 2022 If you want the batts to go into idle... change the ESS to "optimized without batterylife" and set it to 95% unless grid fails. The batts will charge to 100% if there's enough solar, if there's not enough solar, they'll discharge to 95% and go into idle (taking power from grid direct to loads) unless grid fails then they'll start discharging further. This is what I did because I'm also not keen on the constant charge/discharge around 98-100% when in the Keep batteries charged mode. Mine is set at 85% now because we have consecutive overcast days with high chance of grid fault. But normally I set it to 25% and let the batts cycle down to that each night and minimise my power bill. Quote Link to comment Share on other sites More sharing options...
molesza Posted November 14, 2022 Author Share Posted November 14, 2022 1 hour ago, 0012 said: If you want the batts to go into idle... change the ESS to "optimized without batterylife" and set it to 95% unless grid fails. The batts will charge to 100% if there's enough solar, if there's not enough solar, they'll discharge to 95% and go into idle (taking power from grid direct to loads) unless grid fails then they'll start discharging further. This is what I did because I'm also not keen on the constant charge/discharge around 98-100% when in the Keep batteries charged mode. Mine is set at 85% now because we have consecutive overcast days with high chance of grid fault. But normally I set it to 25% and let the batts cycle down to that each night and minimise my power bill. Thank you very much. I will try that and see what happens. I have seen in the freedom won installer document it says its mandatory to have it on " Optimized with BatteryLife" or "Keep Batteries Charged". Wonder if this effects warranty. Their reasoning for that is so batteries don't stay discharged for too long. I am keeping them at 95% though. Imagine that wont be a problem. Thanks again! Quote Link to comment Share on other sites More sharing options...
molesza Posted November 14, 2022 Author Share Posted November 14, 2022 I tried "Optimized with BatteryLife" after an hour the PV stop producing when I was at 97%? I then put it back to "Optimized with BatteryLife" and it started to produce again. Gave it a few minutes and turned back to "Optimized without BatteryLife" and it is still charging. I'm going to leave it and see what happens tomorrow as it is supposed to be a cloudless day for once! Will report back on my findings. Quote Link to comment Share on other sites More sharing options...
0012 Posted November 14, 2022 Share Posted November 14, 2022 Completely fine to opt for the "with BatteryLife" option, I just don't use it because I monitor often and don't let SOC stay that low. The result if used at 95% should be very similar to the "without BatteryLife" option anyway. Quote Link to comment Share on other sites More sharing options...
0012 Posted November 14, 2022 Share Posted November 14, 2022 42 minutes ago, molesza said: I tried "Optimized with BatteryLife" after an hour the PV stop producing when I was at 97%? I then put it back to "Optimized with BatteryLife" and it started to produce again. Gave it a few minutes and turned back to "Optimized without BatteryLife" and it is still charging. I'm going to leave it and see what happens tomorrow as it is supposed to be a cloudless day for once! Will report back on my findings. It is dark and cloudy your side so that's why it stopped at 97% maybe. Anyway see how it goes. Definitely overnight with grid available the batt will just sit on 95% in status "idle" Quote Link to comment Share on other sites More sharing options...
Bernardf Posted November 15, 2022 Share Posted November 15, 2022 My Freedom Won 10/8 does exactly the same. When it is full it constantly goes between 99% and 100%. Example of my SOC% chart below (the times where it went below 99% was when usage exceeded solar production because it was a cloudy day). Quote Link to comment Share on other sites More sharing options...
Milan188 Posted November 15, 2022 Share Posted November 15, 2022 4 hours ago, Bernardf said: My Freedom Won 10/8 does exactly the same. When it is full it constantly goes between 99% and 100%. Example of my SOC% chart below (the times where it went below 99% was when usage exceeded solar production because it was a cloudy day). Also happens on my Greenrich battery. But when it is not at 100% it stays constant at that value. Quote Link to comment Share on other sites More sharing options...
Basil Katakuzinos Posted November 15, 2022 Share Posted November 15, 2022 On 2022/11/14 at 3:38 PM, molesza said: I tried "Optimized with BatteryLife" after an hour the PV stop producing when I was at 97%? I then put it back to "Optimized with BatteryLife" and it started to produce again. Gave it a few minutes and turned back to "Optimized without BatteryLife" and it is still charging. I'm going to leave it and see what happens tomorrow as it is supposed to be a cloudless day for once! Will report back on my findings. As the battery fills up, it will start accepting less charge current. I feel like this may be what you are noticing. IE when the battery is closer to 100% it can not charge as fast as it can at 80% You can monitor this on your remote consol under battery parameters, you will see the Charge Current Limit set by your battery. I would stronly suggest setting your batteries to optimised with battery life and setting the SOC limit lower than 100% as this will give your system a buffer to use and reduce your reliance on eskom. Even if it is just at 85% Quote Link to comment Share on other sites More sharing options...
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