Lindsay

Definitely no timed absorb. I would hope that if you set it to equalise then it wouldn't do the absorb cycle the same day, so that there would be no chance of overcharging. I'll try set it up for the weekend when I'm home so I can keep an eye on it. Thanks for all the help

Thanks Coulomb, so do you suggest then that I use the "equalise" setting to force absorb on cloudy days for a couple of hours?

I only run the induction cooker or slow cooker on the weekend and around lunch time. The induction cooker only uses 700W as I avoid running it to the full 1400W. It doesn't at any time pull more than 10amps out the battery as the coil switches on and off in the lowest power mode and when the coil is momentarily off then I can see amps going into the batteries. I've only once in the last couple of months briefly (for less than a minute) pulled over 30amps from the batteries, but that's not normal, I think the inverter was busy switching modes and briefly internally disconnected the solar panels. I guess they probably just trying to cover themselves incase someone drops in lithium batteries without having a bms and destroys something Thanks for the info on the other battery types. There is comms from the 24V Mecer/Axpert, via USB, which is how I'm logging data, but the inverter has no idea what the charge state of even lead-acid batteries are. I'll have a look at what lithium batteries are available and how best they would fit into the system. Unfortunately I've built a lot of the devices in my house around the solar delivering 24V DC, which makes it harder to consider an upgrade to 48V 😐 I took a look at my logs last night, so can now give some further info on the voltages in my setup: The voltage very briefly shoots above 30V sometimes, mostly on days where it is not very sunny, so sometimes the batteries are below absorb then 30V, then it settles on absorb, then the fridge/freezer kick in and the voltage drops again, then they switch off and it goes over absorb briefly again, back to absorb etc. Seems to happen for only a few seconds at a time. This doesn't seem to happen on sunny days when I'm not home, so I don't think I need to worry about this. I see voltages above 28.7V (absorb) for 2.5-3hrs on a sunny day, after this it drops to 27.4-27.6V (float), so it doesn't sound like the premature float bug. However, on a very cloudy day it looks like it might only hit absorb voltages for around 10 minutes Since you were suggesting an absorb for an hour as a starting point, doesn't 3 hours on a sunny day sound too long for my battery bank? Is it maybe being overcharged on those days? Thanks again!

I just checked and last night it was 47Ah, that's across all 4 strings, so about 12Ah per string. I have a fridge, freezer, router, some security cameras, LED lights and chargers for phones and laptop that run off it, so not a heavy load. I have a slow cooker, induction stove and mini-oven, but only use those in the day when there's plenty of sun. I should probably look back properly through my logs and see how it ran last year this time to do a proper comparison. I do notice that sometimes the battery voltage reported by the inverter goes a bit over 30V (pretty sure it has done this since I got the inverter). I think this is brief and just when it's switching modes (absorb -> float) etc so I haven't worried about it. I gather when I find the battery bank is really struggling I should switch out the whole battery bank in one go. I seem to remember the manual saying you shouldn't use any battery type other than lead-acid. However I gather if I get a bms and adjust the absorb and float voltages would it be ok to use a different battery type (lithium etc)? Thanks for all the help, I'll let you know what I find!

I log the data from the inverter, so I'll take a look and see how long it sits in absorb before being dropped to float. If I have to, how long, considering my size battery bank, do you think I should set it at 28.8V? I'll reintroduce the two weaker batteries in their own series-pair back into the battery bank and see how that goes. Should I worry about the slight bulge and moisture by the pressure vent on two of the batteries?

Thanks for the suggestion. Last winter I probably mains charged my battery only a couple of times, when it was very rainy/cloudy, surely I would have noticed the issue then or sometime in the past or is this much more noticeable as the batteries age? I know I can set a timed equalise, could I set this for every day though at 28.8V? Do you think I should put the two weaker batteries back in the bank as a series pair?

Hi everyone, I started finding a couple of weeks ago that my batteries were getting quite low overnight. Each battery is 102Ah 12V lead acid deep cycle with the full bank 408Ah 24V. I took the following readings from them at 11pm one night and assigned a letter to the top left of each battery. The L voltages are while under a light 2amp load and the U voltages were after I disconnected and waited a couple of minutes. You can also see the load in amps across the pairs (measured with clamp meter) and see that the B-F pair isn't doing much: This resulted in me removing F and D batteries and moving H to where F was. F and D seemed to be the weaker batteries, but I'm not sure I'm entirely correct and I'm still finding that my batteries don't fully charge even on a sunny day. They always seem about 10-20Ah below charge and I turn on my Mecer/Axpert to charge them from the mains for 30-45 minutes each night. With regard to my Mecer/Axpert settings I have a 28.8V bulk charging voltage and a 27.6V float and my maximum charging current is 40A. In addition I notice a slight bulge in D and E and some slight moisture by what looks like a vent, however I wouldn't think it'd ever be overcharged and I've checked their temperatures while charging and they seem ok. So I guess I just want to know if this is normal for roughly 3 year old deep-cycle batteries, where I have pulled on the longest nights 40Ah overnight? I'll admit that I did not buy all the batteries at exactly the same time, so there may be some additional ageing from that. Should I try put the weaker batteries in their own pair and back into the battery bank? Should I reorganise the ordering of all the batteries in the bank? Thanks in advance for any responses. Regards, Lindsay

This looks very cool. I see it exposes the values on MQTT and builds graphs/meters. Are the graphs and data exposed on the local webserver on the Raspberry PI? Are there any English instructions for getting this running? Thanks.

Attached is my full code for Python3 which will try to read from the inverter every 5 seconds and timeout if the read takes longer than 12 seconds (I've only tested the QPIGS, but you should be able to change the commando variable if you want to read other data). Enjoy! inv.py

Ok, so I seem to have it working now in Python 3. After Gnome mentioned the encoding and I skimmed the articles above I looked at the encoding and changed my original code, which was based on nikitto's post from June 4, 2017 in same topic: ### code above removed, see nikitto's post from Posted June 4, 2017 in same topic ### calc_crc(comando) print('Command='), comando print('CRC='),crc crc1=crc[0:4] crc2=crc[0:2]+crc[4:6] crc1=int(crc1, base=16) crc2=int(crc2, base=16) scomm = comando+chr(crc1)+chr(crc2)+'\r' bcomm = sCommand.encode('ISO-8859-1') fd = open('/dev/hidraw0', 'rb+') fd.write(bcomm) r = fd.read(nbytes) j = r.decode('ISO-8859-1') s = j.split("\\") print s i = s[0][1:].split(" ") print i fd.close() So I open the connection to read/write bytes (not strings) and encode the string before passing it to the write and decode when reading (and removed the .encode('string-escape') from the original code). This seems much more reliable and I didn't see any errors when running this code. I hope this helps others that are trying to get it working in Python 3. Thanks again Gnome.

This is cool, will check it out. Yes, I am still to get home and post some code But I am using QPIGS as you mention. I see the the file handling and character encoding changed between Python 2 & 3, I found a couple of resources to look at: https://portingguide.readthedocs.io/en/latest/strings.html#file-i-o https://medium.com/better-programming/strings-unicode-and-bytes-in-python-3-everything-you-always-wanted-to-know-27dc02ff2686 https://docs.python.org/3/howto/unicode.html https://realpython.com/python-encodings-guide/ So this is probably the issue!

Hi Gnome, To give some further background, my SD card in my Raspberry PI went corrupt and during rebuilding now 2 years on, some of the libraries for an ADS1115 that I also monitor now appear to only work in Python 3. Since I access both the inverter and the ADS1115 from the same script I am forced to upgrade it to run on Python 3. When I had problems getting it to run in Python 3 I created a test script that just reads from the inverter. I then fixed it as best I could to run in Python 3, however as mentioned I only get a full valid response for around 10% of the time. Raspbian Buster does actually also support Python 2, so if I call this exact same script in Python 2 then it works around 80% of the time. My 2 years old script would also fail sometimes in Python 2 and I'd just retry and get a value. So I'm pretty sure it's not the cable. I am only using the QPIGS command, calling every 15 seconds, I just need to read the current voltage, solar watts etc. I'll have to post my code tonight. It's a bit hacked together to try anything to get it to work - first it wouldn't even run due to functions no longer supported in Python 3, then I was either getting errors or no response, so getting it to 10% was actually an improvement 😕 I'm also going to try run the hibrido_test.py posted above. Thanks!

Hi, sorry to revive an old topic. I have had to rebuild my Raspberry PI 2 with the latest "Buster" version of Raspbian and I now have to run the code in Python 3. Has anyone managed to convert this code to work in Python 3? I know that commands like ".encode('string-escape')" are no longer supported and, while I seemed to get it working without this, by returning as a byte array, the rate of failure is much higher than it used to be. If I repeatedly query the inverter via USB every 15 seconds, around 1 in 10 queries result in a valid response. Most of the time I get either 0 response or the start or end of the returned value is garbage or missing, resulting in less data than expected for the QPIGS command. Some help here would really be appreciated as I was up until 5am Sunday morning trying to get this to work and spent several hours on Sunday also trying to get it to work.

Hi all, I use the QPIGS command from Python to monitor my Mecer (Axpert) 3kVA 24V inverter from a Raspberry Pi. Currently I leave it in SENS mode in the settings so that it only fully turns on the inverter when a load is detected. If the load is over about 100W then this works fine and it turns on, however anything less than this and it won't turn on. Is there a way to turn it on for lighter loads without going through the settings using the buttons on the front and switching it to SDS (I think that's the other value)? I was hoping maybe I could use a command in Python from the Raspberry Pi and then trigger the script from my phone. Thanks.

Yes, but I bought them in pairs at different times, so it was easier to stick to to pairs and also I have 4 that are closer to the house than the other 2, so for now I'll probably keep it this way unless I move them all to the same place. 40A x 25 = 1000W, although I've seen it overshoot when charging by a few amps and then correct itself. I've only recently been logging the output and the most it's reported the panels at is around 1200W. I think the battery bank is ok with that, I've seen brief voltages up to a bit over 30V when running an induction cooker on the inverter and everything still seems to be ok. I worry more about my direct DC appliances, a 24V fridge/freezer and then some other items such as 24V car USB chargers and some DC-DC buck converters. I think I already fried one 24V USB charger due to the voltages so I might rather replace these with DC-DC bucks that can handle up to 38V. Yeah, I'm just being paranoid. I have 16mm cable (with 60amp fuse), so should be good with 60amps and the cable could probably handle more (although when I've looked online I've seen all sorts of varying tables on how much 16mm can handle). My loads, as I said, are mostly DC. But I do occasionally run the induction cooker, slow cooker etc usually less than 1000W. I've also got a low current circuit breaker on the AC because if I pull more than 60 amps from the batteries and the fuse trips, I hear that these inverters don't like being disconnected from the batteries when there is solar power present and it damages them (according to the supplier). Is this true? Yes, I currently have my 3 sets of panels each coming in on 4mm cable fused separately, then joined at the disconnect and 16mm from there. Thanks Coulomb and others. For now I'll leave my panels at 1555W to be safe.

Well I have a BTech in Electrical Engineering, I might be a but rusty, but I think I'm ok there I've got all the dc breakers, fuses etc. I wasn't sure how these things would handle excess current, at the moment I'm not pushing more than 30 amps from the panels, so half the 60amps the MPPT can handle (even though I'm slightly over the max panel watts). I'm also limiting the battery charging to 40amps as I'd prefer to have thicker cables if I'm going to push anymore than that. Thanks again for the info!

Thanks, yes, Voc is 145V and PV MPPT range is 60-115V, so I guess changing from strings of 2 to strings of 3 would then allow me to add even more panels. But saying that does it mean that I could actually have 6 parallel strings of 3 in series, 18 x 260W panels total, that's a lot more than 1500W? 3 in series puts MPPT voltage at ~100V and the strings being parallel is 6 x 8A per string = 48A. If your panels did exceed 60A wouldn't the controller just not use the amps above the charging maximum (as you can set this in software below 60A if you want to) or would it go into fault? (btw I installed my solar myself, and I'm not sure the supplier would know the exact workings better than the people on this forum!)

So I have the Mecer 3kVA 24V (Plus model) off grid inverter that can take up to 1500W of PV. Currently I have 1555W (~260 x 6) panels attached to it in 3 x parallel strings each containing 2 panels in series. As such the PV voltage is in the 60-70V range. My question is can I keep adding more strings of two panels in parallel without causing issues? Would there be any disadvantage, I know that if I have the inverter on on a sunny day and the load switches on and off often that the voltage can overshoot and occasionally push 30V to the batteries, would this make that situation worse? The PV voltage would stay the same of course and my expectation is that it just would never charge with more than its rated 1500W of power. The advantage of adding more is of course is that it'd help on the very dark winter days where there's not enough sun to currently fully charge the batteries. Thanks in advance.

Thanks for the responses. I've seen that sticker, but will have to look for it again. I know I bought mine in July or August last year, so I think it would have been manufactured closer to the beginning of last year. As I said, it does click back on and start charging again after about a minute, maybe a bit longer than that. My induction cooker is only 600-800W in the low power mode that I use it in. But I've even noticed this issue with smaller 300W loads that click on and off (like a 3d printers heating element) that the voltage goes all over the place. My batteries are only between 2-3 years old. My model is the one with only has the USB port, no RJ-45 or COMMS board.

Thanks, I was able to find some other commands that worked to get the default inverter settings as well as the current settings. When I run QMOD I get FH, which according to the communications document you linked to means Fault and Power saving. I don't have any fault showing on the inverters screen and no fault LED flashing under it either, so maybe that mapping is different for my model. I didn't get any response when trying to get that detailed temperature information. When I mentioned "time out on the first run" I meant that after issuing the command I never get anything back. The Python code sits waiting for a response and after a minute I just stop it manually. If I run QPIGS again straight after, then it runs quick and returns the results in a couple of seconds. I probably just need to set something to retry in my code. Thanks again for the manual, I was able to work out all of the QPIGS values that I am getting back which seem the same for my inverter.

Hi all, I bought a Mecer 3kVA (24V - 1500W PV) off grid inverter last year and have noticed some odd behaviours. I've currently got the inverter set to SENS(?) where it pulses every second or two and then seems to only switch on if a load of at least 100W is detected. However, I notice it turning itself on for a couple of minutes several times an hour, even with no load and then switching off again. I've also noticed that during the day I'll sometimes hear the relays inside clicking and the battery voltage will start falling, even though the panels are still in full sun. Then after about a minute it clicks again and then starts charging the battery again. I'm not sure if it is just switching from absorb/bulk to float, but I don't think I have any major load kicking in at the time. If I have switched the inverter on (so not in SENS) and I have a variable load on the inverter (like an appliance that switches on and off with temperature, for example an induction cooker) then the voltage jumps around and can briefly go over 30V sometimes before correcting itself back to 28.8 or 27.4V. It worries me that I have some 24V fridges and other 24V devices (DC-DC buck converters etc) that connect direct to the battery and now have to deal with the voltage spiking over 30V. Are the behaviours above normal and has anyone else noticed these? Also, are there firmware updates for these inverters and if so how do you update them? Thanks all!

Hi all, I am trying to read all the data I can get over USB from my Mecer 3kVA (24V - 1500W PV) off grid inverter using Python on a Raspberry. I'm using some modified code that Nikitto wrote a few months back and have a few questions. I seem to get the real-time values using the QPIGS command, but I also wanted to know what the other commands were for, QID, QFLAG, QPI, QMOD? In case I'm missing out on any other data that might be useful. I also notice that if I haven't run the QPIGS command for a while it will time out on the first run, but then if I cancel and rerun it again it works fine. Anyone else notice this? Is there another command I should be calling first in order to set up the communication? Nikitto's code returns an array for QPIGS, I've managed to figure out some of those values: [0]: 0 = Inverter off, 1 = Inverter on [1]: ? [2]: Inverter voltage [3]: Inverter frequency [4]: ? I think inverter watts or VA [5]: ? I think inverter watts or VA [6]: ? Most of the time 000 for me [7]: ? Usually between 300 - 500 [8]: Battery Voltage [9]: Battery charging amps [10]: State of charge in percent [11]: Temperature of inverter/charger (divide by 10) [12]: ? Usually between 0000 - 0022 [13]: Solar panel volts [14]: ? Seems similar to battery voltage, usually around 0.1V difference [15]: Battery load amps [16]: ? Some bit string, representing state, have seen 10010110, 10110110, 10010000 [17]: ? Always seems to be 00 for me [18]: ? Always seems to be 04 for me [19]: Solar Watts [20]: ? Seem 000 and 101 here Do any of you know the ones I am confused about (marked ?) or whether I have any wrong and what do those other commands do, QID, QFLAG, QPI, QMOD etc Thanks in advance!