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yes, you are correct, RS485 is for the battery and RS232 is used for 'PC' com.. I used it to connect the WiFi dongle that came with the inverter what exactly 'EVE' means?.. I thought those are for 'electric vehicle' or something.. 😅 I am still new to batteries ______ I've split your post into bullet-points just to make it easier to replay 1. Yes, I'm totally off grid .. I use gasoline inverter generator if I really need to. ... What does SA stand for ? 2. I do have a battery tester but it's for car batteries.. it requires a CCA parameter of at least 100A and is thus useless for most deep-cycle batteries.. at least I think it is ? deep-cycle lead-acid batteries are not designed for high current ? 3. (and 4.) when I think about this.. splitting the circuit doesn't give me more energy, because I would still have the same amount of PV panels and same amount of sun.. and PWM chargers are just less efficient than MPPT.. is that right..? I mean, why would I have two separate paths for storing the same amount of energy if I can have just one, more efficient path ? How did you calculate 25h for 50W ?.. my thinking is like this: 48V with 100Ah is 4800Wh.. then 4800Wh / 50W = 96h .. that is 4 days.. which I think is reasonable for such a small load.. I mean, that would be 100kg of batteries .. in those cheap UPSs, one small 15Ah battery can power my 450W computer for 15-20min, with inefficient inverter and I actually have 8 batteries in 4s2p configuration.. so double the capacity, 9600Wh .. that's 8 days for 50W load.. of course, when the batteries were new.. and again, seems reasonable for only 50W load.. that's 200kg battery 4. 280V is actually around the most efficient voltage for this kind of charger, I think.. the range for this system is 60-500V DC.. it can easily support 12 x 350W panels in series 5. I do not NEED 6.2kW per se.. but it is good to have it If I need it .. it is true that it's easier to get 2 new 12V batteries when old ones fail.. but I can't afford to change the inverter now.. in the summer when I use refrigerator, freezer and water pump (and girls using their hair dryer, hair-iron) it is good to have a little bit of 'reserve'

yes.. I don't recommend this also, if you don't know what you are doing.. but I had a variable transformer before the rectifier and a limiting resistor and I never had grid AC input and rectified PV input at the same time Also, I wanted to lower the voltage to 120VDC to test if the whole PV range is working

ah yes, that makes sense I've seen some good comments on NKON batteries.. do you know another good supplier in europe/EU ?

The inverter is working now.. thanks to shakeel ahmad's help.. inverter, AC charging, AC bypass, PV charging battery-inverter and PV-inverter work now.. when I was reassembling everything back in the case, I forgot to connect one 4pin cable to the MPPT board, but shakeel ahmad found where to connect it I'm not sure what was the problem in the beginning .. I did found a lizard's tail 🦎 under the main PCB and some dead bugs 🐛🐞 around PV connections 🤣 .. but I didn't actually do any 'repair'.. I guess the lizard and bugs made a short somewhere 🤔 I didn't have enough PV panels or batteries for testing so shakeel ahmad suggested to make a bridge rectifier with a capacitor from 230V AC to DC and use it for PV input.. Also, I used an electric scooter battery for battery input and everything seems to be working correctly now

okay.. thank you all for help.. I will probably buy LiFePO4 cells and make a battery instead of buying a commercial one.. I have built a battery for electric scooter before, but it was a LiIon (18650) battery.. so I know little bit about BMSs and such This is the one I'm thinking about : https://eu.nkon.nl/rechargeable/lifepo4/prismatisch/rept-cb56-100ah-100a-lifepo4-3-2v-a-grade.html 492€ for 16 cells..30,75€ per cell.. that pretty cheap for grade A cells, right? The description says this: "cycle life: min 6000 till 70% @ 0.5C" .. what exactly does that mean?.. minimum 6000 cycles with max 70% DOD at 0.5C discharge.. so, to 30% SOC at 50A ? ___ My inverter has a battery com-port (rs232).. do you recommend any specific make/model of BMS ? I'm thinking about Jiabaida .. they are cheap, come with bluetooth, rs232 UART, temp sensor, etc.. I would put it all in a plastic box with styrofoam for insulation..and probably insulate the whole basement with styrofoam .. the BMS and cells heath should keep temperature above 0.. right?

temperatures there can go around 0 sometimes.. not much below 0.. maybe -1 but usually only for few days through whole winter.. my system is in the basement yes, when you put it like that.. I'm now considering putting isolation there so.. you really think that lead acid should be avoided ? But why? you mean lifepo4 or lithium polymer like the batteries in phones ? I don't know much about either but I don't trust lithium polymer batteries because of the fire danger.. I leave that house for months and don't want that in my house while I'm not there

I have a 48V off-grid solar system(ANENJI 6.2kW hybrid inverter).. and I use AGM batteries.. I have 8 pcs, 100Ah each, in a "4S2P" configuration.. so, 2 in parallel and 4 of these pairs in series .. so this should be 48V 200Ah or 9600Wh battery. I should mention that now I have 14 PV panels .. 7 in series and 2 series in parallel .. one series on each side of the roof .. these are all used and most of them are the same brand and model, but I do have couple of different ones.. most of them are 350W and 2 or 3 are 450W.. first I had only 5, then 10 (5 for each side of the roof), then bought 2 more and recently 2 more.. I buy them when I find a good price and have enough money to afford it.. I know this is not perfect but it is what it is. I bought more panels because I though that I didn't get much sunlight to the charge batteries during winter.. but now I'm not so sure about that. (my location is around 44-45° latitude) Problem is that during the winter the batteries regularly go to 0% .. like, every night.. sometimes even before sun goes down.. during the summer, they can last whole night but get to 5-15% SOC But during the winter, I only have connected 5 cameras and a wifi router, nothing else, not even light bulbs, because I'm not in this house during winter.. I just need the camera surveillance and wifi for them .. this is around 50W load(the inverter app says its 25-27W, but let's say its 50W).. let's say the night lasts around 15h and the inverter needs another 100w just for being ON .. that should be around 150W * 15h = 2250Wh !! Are my batteries so bad that they can have only 23% of their original charge !? To me this seems ridiculous.. I have 200kg of batteries and they can't power 5 little cameras and a router for more than 6-8h !?!? Realistically that's 50W load, and I can't get one night with that?!? I've never bought new batteries because they are so expensive.. I always bought them used.. but still, I would expect they would have at least 50%. Few days ago I did the 'equalization' program that my system has.. for that to work I had to change the 'battery type' setting to 'flooded' or 'user' .. so I set it to 'user' .. then I can set the 'bulk voltage', 'floating voltage' and 'low DC cut-off' .. and I did set this correctly, as the battery specification says.. I also used an inverter gasoline generator for grid AC input because I was afraid there was not enough sun for this. The inverter user manual is very shy on information about this program.. user can only set the equalization time, timeout, interval and voltage.. it says it can go up to 64V but I could only go to 62V.. not sure if it is a typo in the manual or something else.. the time and timeout setting were left at default.. so, 60min and 120min, respectively While it was 'equalizing', the first battery pair in the series got to 16.5V, second pair was lower, around 15V and 3rd and 4th pair were only around 14V.. also, first two pairs got a little bit warm, especially around first cell in the battery.. so I guess my first pair is the worst, then the second pair and then 3rd and 4th are the same and better than the first two.. but I remember that last year, also the first pair was the worst so I bought 2 more batteries and replaced them. Can it be that the first batteries in the series get used more or something, or is it just a coincidence? I repeated this 'equalizing' program 3 or 4 times that day and the batteries did 'equalize', I guess.. last time I did it the batteries were closer in voltage than the first time and the following night they got to around 40% SOC.. but the next day only around 25% and now its the same as before I was thinking about switching to liFePO4 batteries because my system supports it but when I realized that those batteries can't work around or below 0°C , so I gave up on that.. now I'm thinking about buying new AGM but lower capacity .. say, 50 or 80 Ah.. just because of the price .. but I'm worried they would also quickly go bad and warranty would not cover it.. I know that you should not use more than 50% because otherwise the battery quickly gets damaged .. but my inverter has an AGM battery type in the settings and I would expect it wouldn't discharge the batteries below 50%.. is this correct? Should I set 'user' battery type and set my parameters for cut-off and everything else in order to not let the batteries discharge below 50% ? What about GEL batteries ? I read that they can get greater DOD without getting damaged

I have the Revo vm II 5.5kW device ... yesterday I was rearranging the panels on the roof.. when I was connecting back the second PV cable(don't remember if it was + or -) to the device I must have shorted it to the chassis or to other PV cable (- or +) that was already connected.. because I saw and heard a big spark.. much larger and louder than usually when connecting PV to the device. After that the device menu shows 0V, 0A in the menu for PV input and no graphics for PV charging on the LCD.. but I can measure around 140V with a voltmeter. The device works with 120-450V PV and while the device was working before, I think I remember that even when it was getting dark and PV voltage was less than 120V, the device would show that voltage in the menu.. but I am not sure 100% I also remember that at some point yesterday, when I was reconnecting all of the cables to the device, I disconnected the batteries before disconnecting the PV cables.. the device made some buzzing noise and the LCD went blank(no graphics at all) but the LCD backlight was still on and slowly faded away in abut 3-5 seconds.. Now the device works when I connect batteries and turn on the switch on the right side.. LCD turns on and shows menus and graphics, and the inverter works.. I have 220-230V on AC output... but before it worked even when the switch was off and PV panels were connected.. even at night, when I turned the switch off, I still could see the LCD and use the menu, only the AC output was off I have disassembled the device and can't find what is wrong.. I should mention that I have some knowledge about electronics.. I have repaired this device about 2-3 years ago when charging didn't work, mosfets and some resistors and diodes were fried. Now when I connect only the batteries and turn the switch on, but disconnect the PV panels, I can measure around 5V on PV input... Now the device is at my other house and I have only 4 panels in my backyard and the weather is not so good.. so I only have around 120V on PV ... when I connected those panels today and measured the voltage at the PV input, it seems like the device is trying to turn on but fails, because I see the voltage is 120 for around 4-5 seconds and than for 1 second it drops to 115V and that repeats periodically all the time