October 30, 20223 yr Hi all, I've recently ventured into a backup system to get past loadshedding and have had a Sunsynk 5 kw inverter and two Dyness 48 v 4.8kw batteries installed (parallel). Everything works great except, when I pull around 2600 - 2800 watts the inverter shuts down. I suspect there are too many amps being pulled and, as the batteries are 0.5 C rated, only discharge half the available power. Is there any way to increase the available power for discharge i.e. a third battery ? My 5kw inverter is effectively only providing half of its input as a result of the C rating of the batteries. How can I get closer to around 4400 watts etc for use? Is the only way to change batteries? Thanks,
October 30, 20223 yr Maybe post some of your settings. That does not sound correct that you are being shutdown when you do 2600-2800 watts. Unless you are doing that usage constant for a good many hours. At that high usage rate you should be getting close to 4 hours run time if the batteries are nicely balanced and fully saturated on the previous charge cycle.
October 30, 20223 yr If you have 2 x 4,8kwh 0.5C batteries that means you should be able to pull about 4,8Kw for about 2 hours. Sounds like your settings on the inverter are incorrect.
October 30, 20223 yr Author 1 hour ago, WannabeSolarSparky said: Maybe post some of your settings. That does not sound correct that you are being shutdown when you do 2600-2800 watts. Unless you are doing that usage constant for a good many hours. At that high usage rate you should be getting close to 4 hours run time if the batteries are nicely balanced and fully saturated on the previous charge cycle. I've attached some photos of all the settings pages - not the neatest but difficult to get past the 3MB limit. Also, when the inverter does go off the relevant fault code is F56 - low DC voltage.
October 30, 20223 yr 3 minutes ago, Balneuwes said: I've attached some photos of all the settings pages - not the neatest but difficult to get past the 3MB limit. Also, when the inverter does go off the relevant fault code is F56 - low DC voltage. Change your inverter battery settings to match what the BMS is sending to the inverter, from your images that would be 53.5v set that to all 3 settings on your battery charge screen. Should not really make much diffs in your usage results but do that anyway just to be safe in case your bms comms go down. You settings so far look ok. Maybe also post your actual inverter timer settings and setup settings as the ones you posted are not altogether helpful for the issue you describe fully.
October 30, 20223 yr 10 minutes ago, Balneuwes said: I've attached some photos of all the settings pages - not the neatest but difficult to get past the 3MB limit. Also, when the inverter does go off the relevant fault code is F56 - low DC voltage. The DC low warning points to the battery side so either the settings are not altogether correct or the state of charge of the battery is not correctly reflecting what is actually left in the battery. Might be that you simply need a good full absorption cycle on the batteries. May also be some of the cells are out of balance which could result in premature low voltage state being reported to the inverter during cycling. Edited October 30, 20223 yr by WannabeSolarSparky
October 30, 20223 yr Author I might only add that when the inverter did go off the amps being pulled were in the region of 56 (which were marked in orange) when the kettle was turned on. Watts remained around 2700 - 2800. Edited October 30, 20223 yr by Balneuwes
October 30, 20223 yr 1 hour ago, Balneuwes said: These are the only remaining settings - any idea? On the second image you have limit to load only. Do you have the CT coil installed? Maybe provide a scrrenshot of the inverter home screen where it shows your energy flows. If you do and its installed correctly then you should uncheck limit to load only and then you can decide if you want to proritise the Load on the essential side by checking the Priority Load box. On the 1st image setting you have SOC/V set to 100% all day so you will never use battery unless there is no grid. Is that the desired working mode you want?
October 30, 20223 yr 1 hour ago, Balneuwes said: I've attached some photos of all the settings pages - not the neatest but difficult to get past the 3MB limit. Also, when the inverter does go off the relevant fault code is F56 - low DC voltage. On your LiBMS screenshot the discharge amps is only 50A and that is your problem. It should say 100A. Looks like your batteries are not communicating with each other to tell the inverter that there is 2 batteries thus doubling your discharge capability. Check the comms cable between the batteries . When you get the LiBMS screeen to show 100A discharge limit its working correctly . Also change the discharge amps on you charging screen to 100A as 120A is too high. I also notice you dont have signal island mode ticked , make sure you have a neutral earth relay installed and then tick signal island mode. In your system mode settings you can untick the Use timer option as that will keep the batteries full ,kind of pointless to use the timer when you dont have solar... Edited October 30, 20223 yr by Nexuss
October 30, 20223 yr You right, I did not notice that, may very well indicate comms not altogether correctly setup between the batteries.
October 30, 20223 yr 1 minute ago, WannabeSolarSparky said: You right, I did not notice that, may very well indicate comms not altogether correctly setup between the batteries. And that is why forums like this are such a valuable resource, different eyes spot different things 😃
October 30, 20223 yr Author 40 minutes ago, WannabeSolarSparky said: On the second image you have limit to load only. Do you have the CT coil installed? Maybe provide a scrrenshot of the inverter home screen where it shows your energy flows. If you do and its installed correctly then you should uncheck limit to load only and then you can decide if you want to proritise the Load on the essential side by checking the Priority Load box. On the 1st image setting you have SOC/V set to 100% all day so you will never use battery unless there is no grid. Is that the desired working mode you want? This is a backup system only to get me through the bouts of loadshedding - I am unsure what a CT coil is or its function. I'll ask my installer about this - the way I understand is that the inverter is wired directly to all circuits on the main DB except the stove, geyser and swimming pool.
October 30, 20223 yr Author 31 minutes ago, Nexuss said: On your LiBMS screenshot the discharge amps is only 50A and that is your problem. It should say 100A. Looks like your batteries are not communicating with each other to tell the inverter that there is 2 batteries thus doubling your discharge capability. Check the comms cable between the batteries . When you get the LiBMS screeen to show 100A discharge limit its working correctly . Also change the discharge amps on you charging screen to 100A as 120A is too high. I also notice you dont have signal island mode ticked , make sure you have a neutral earth relay installed and then tick signal island mode. In your system mode settings you can untick the Use timer option as that will keep the batteries full ,kind of pointless to use the timer when you dont have solar... I think this may very well be the issue. I read on a different forum that the C rating of the batteries do not increase in parallel - i.e. a 100AH battery at 0.5 C coupled with another will still only provide 0.5 C. Does this however mean that it would be 0.5 C @ 200AH meaning I could draw 100 AH in an hour (thus the whole 4.8 KW)?
October 30, 20223 yr Author Going through the history on the most recent bout of loadshedding it also appears that my batteries SOC went downt to about 78 % after roughly 2hours / 2,15hours of loadshedding with around a 560w -1KW draw - I think this is further confirmation that the inverter is not detecting two batteries? Edited October 30, 20223 yr by Balneuwes
October 30, 20223 yr 4 minutes ago, Balneuwes said: Does this however mean that it would be 0.5 C @ 200AH meaning I could draw 100 AH in an hour (thus the whole 4.8 KW)? Correct , but only if you have comms between the 2 batteries ,as it stands now the inverter is only seeing one battery.
October 30, 20223 yr 7 minutes ago, Balneuwes said: This is a backup system only to get me through the bouts of loadshedding - I am unsure what a CT coil is or its function. I'll ask my installer about this - the way I understand is that the inverter is wired directly to all circuits on the main DB except the stove, geyser and swimming pool. That is important info, thanks. You should definitely enquire with your installer about the CT coil, that is a vital part of the Sunsynk inverter to ensure it operates optimally.
October 30, 20223 yr 5 minutes ago, WannabeSolarSparky said: That is important info, thanks. You should definitely enquire with your installer about the CT coil, that is a vital part of the Sunsynk inverter to ensure it operates optimally. It almost seems like the CT coil and earth/neutral bond relay is like the bane of most installers lives. 🤣
October 30, 20223 yr 2 minutes ago, Nexuss said: It almost seems like the CT coil and earth/neutral bond relay is like the bane of most installers lives. 🤣 So very very true, and ALL the manuals and instruction videos highlight the importance of both. Most of these guys just wing it and hope it all works correctly 🤑 it's mostly called greed.
October 30, 20223 yr Author Thanks very much @WannabeSolarSparkyand @Nexuss for the helpful advice. My installer is a great guy and I'm sure he will sort it out now that we have a good idea what the issue is. What a brilliant and helpful forum. My first foray into solar was a couple months ago by burning out the MPPT controller in our camp trailer (panels in series just sounded so much cooler) and having to panic research and reinstall a new Victron unit the day before our camping trip. Really enjoying the journey to a off grid system. Edited October 30, 20223 yr by Balneuwes
October 30, 20223 yr 2 minutes ago, Balneuwes said: My installer is a great guy and I'm sure he will sort it out now that we have a good idea what the issue is. Great, do follow up here and let us know how it all turned out 😀
October 30, 20223 yr 28 minutes ago, Balneuwes said: Thanks very much @WannabeSolarSparkyand @Nexuss for the helpful advice. My installer is a great guy and I'm sure he will sort it out now that we have a good idea what the issue is. What a brilliant and helpful forum. My first foray into solar was a couple months ago by burning out the MPPT controller in our camp trailer (panels in series just sounded so much cooler) and having to panic research and reinstall a new Victron unit the day before our camping trip. Really enjoying the journey to a off grid system. In addition to checking the communication cable between the two batteries you also need to check if the dip switches on the batteries have been set up correclty for the master and the slave
October 30, 20223 yr Maybe just a side issue, but why is the inverter set up as a slave? From what I can see you are not running multiple inverters.
October 30, 20223 yr 22 minutes ago, GreenFields said: Maybe just a side issue, but why is the inverter set up as a slave? From what I can see you are not running multiple inverters. If you only have one inverter it doesnt matter . The default is slave .
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