Piet de Pad

For whom is interest I found and interesting article about over discharging Not easy to read. https://www.sciopen.com/article/pdf/10.26599/NR.2025.94908060.pdf I found 3.1.1 Electrode (1) : LFP and interesting section.

Hi taliaB, Thanks for responding. Yes Im going to connect the BMS again before I do a discharge test. I did look at steve87 his comments and take his knowledge in consideration.

Hi HennieL Thanks for you reactions What was the temperature......... bad i live in mid Mexico and the temperatures a quite high >30C Have you measured the voltage..... yes I did, all cells were around between 0.24V and 0.32V till 32V I saw a difference in cell voltage, after 40V All cell voltages miraculously became the same. I charged directly the cells not with the BMS connected. After recharging a totally...... never believe what AI says, but yes I saw that AI response of growth of copper and lithium dendrites that cause microscopic short circuits also. Question is how true is that. It might be or its just one of the many article use as a training set. I consider this a point of concern.

Thanks for responding. What charger...... The charger is a CC CV SMPS that I bought at AliExpress, https://es.aliexpress.com/item/1005008877560318.html. It can generate 600W at 80Volt. It has voltage and current potentio meters on it including a display for Voltage and current. You can see the charge in the photo on the right side. Keep in mind this charger/powerfully you set the max voltage you want to reach whne it is not connected to the battery, then you connect and increase the max current you like to charge with. This guerenties that the voltage never get higherthan the max voltage and the current never exeeds the installed max current. How long ...... Not long till I saw the current dropping off. The sudden drop ....... yes LiFePo4 stabilizes. and that takes time, no I cant give you excel sheets Have you only charged..... yes I have charged it only ones, i haven't discharged it yet But now your knowlage... is th battery heathy to use of is it a dangerours ha ha you must have Dutch roots or be a Dutch give you expression"boer maak'n plan" I am a ex-Dutch "boer met beide laarzen in de Klei". Thanks for your response. I am going to test the discharge and measure the capacity see if that is still 50Ahr.

Hi guys, I'm looking for reasoned opinions about a fully discharged Growatt ARK2.5L-A1 LiFePO4 battery. This battery was completely discharged for months, with a cell voltage of 0.3V. The BMS was not working due to this low voltage, so I opened the casing. After opening it, I recharged it with a 0.1A current from 5V to 32V. Then, I went from 32V to 40V (cell voltage) at 0.3A, followed by 40V to 54.4V at 5A. Finally, I charged from 54.4V to 58V using absorption charging. My observations with nothing connected other than the cells in series: At 32V: The voltage drops by 0.6V over a day. Initially, the drop is fast, but it slows down significantly compared to the first few hours. At 54.4V: The terminal voltage drop is around 0.8V, but it stabilizes faster and stops dropping. At 58V: The terminal voltage drops quickly by about 0.8V, but over many days, it stabilizes at 54.8V. I am aware that the 0–32V and 54.4–58V ranges are the steep sections of the LiFePO4 voltage curve. My initial thought was that any losses due to increased internal discharge would show up in these areas. The information I received was that disconnecting a LiFePO4 battery from a charger causes the voltage to drop by about 0.8V as a result of "settling voltage" or “Voltage relaxations”. The terms Voltage Relaxation or Settling Voltage seem important here. Based on this, what are your reasoned opinions? Is this battery healthy and safe to use, or not? Hope to see what you have to say about this. Regards, Piet de Pad

I have a must PV18-1012, 1kW single phase 120Vac that one takes around 10Watt when no load.

Thanks that quite a bit when you go to bed. You need at least 15% battery capacity left over in the en of the day to make sure this one will not drain the battery in 7 hours the time you sleep.

I agree with what you say but if you look at the effect is has on the backup time with a low load it's dramatic. Fore example considering time between sunset and sun rise say 12 hr and an idle load of 75 what it consumes 12x75=900Wh that is more than 20% of a 5kW battery if you include the losses. So I do believe that idle consumption is an important parameter to know. You are right most people have no idea how these things work and yes they accept it as it is. Thanks for you response

Hi denns thanks for responding to my message. Can you tell me if some has measured that 10Watt idle load or is that just an estimate.

Hi, I would like to know if I have missed anything, so please let me know what you think about this. The voltage at my home is too high and cannot be lowered; it is around 130/260V and sometimes even higher. I came up with the idea to install an auto-transformer at the entrance of my house to step down the AC voltage by adding two 25-turn, 5.3 mm² (AWG 10) laminated copper windings on both sides of the coil. I tested it with two loads of 1 kW each on both sides of the auto-transformer. It worked well, and after an hour, I did not notice any temperature rise. Below is a schematic of how I plan to install it at the entrance of my house. There are two ways I can connect this auto-transformer: either using the 260V as shown in the image or by connecting it to the 130V line or the utility. When I connect it to one leg (L1) of my split-phase utility, I have no problem if the neutral is lost — in that case, I simply lose power. However, when I connect it as shown in the image to both L1 and L2 phases of the utility, there is a risk of over-voltage if the neutral connection to the transformer is lost. My question is: assuming I use proper cabling and connectors, is this a risk I need to consider? Is there anything else I might be overlooking that you think I should know? Thank you!

Hi friends, I am planning to buy an SPF3000LMV or a Must PV33-6048., 3kW is good enough for me. Both have their advantage and disadvantages. In general, the idle load and the inverter efficiency is my point of concern. Does anyone have a good suggestion what to buy and/or can tell me what the idle load is of a Must PV33-6048. Tell me what you think. Thanks Piet de Pad.

That is correct, I measured a 1500Wat peak load at startup and my must 1kW 12V hybrid inverter switches over to grid mode when that happens after 18:00. After 4 minutes it switches back to battery mode, but then the compressor is already running and so it will continue to run in battery mode. During the day when I have solar and battery, he doesn't switch and can handle the overload. I believe it's the BMS that is the bottleneck that one blocks due to overload and makes that the Inverter switches.

Well I have no account yet to access the S-miles web page. The application in the past allowed me to make an account myself, but that option no longer exist in the version of 2025. I have requested Hoymiles, but they don't respond (yet). The W100 has no HTTP interface that I know of.

Hi I have three MI350 hoymiles inverters with unreadable serial numbers stickers. I do have a DTU-w100 with serial number. Can any of you tell me how I can recover the serial numbers of the three MI350 inverters, Thank you help is appreciated. regards