My Growatt doesnt do that, if the AC charging is off or not withing the charger timing window it doesnt charge from AC, it will from solar PV.
New Growatt SPH + Li6532 Installation queries
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stuboy
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So your battery could be completely depleted in the wrong circumstances, that VERY not good!
David_1224
Active member
Hi both. Thanks for the additional comments.
I was in the process of trying to get some more data on the issue but will give you what I have to date.
Firstly @johnb2713
The first thing I did once network connection was established was to check the AC charge setting and it is OFF as you suggested.
I'm now trying to establish if the events I'm seeing are in fact the Growatt "calibration" phenomena which has been referenced in several previous posts, and as noted by @binky, or something more along the lines of what @stuboy has raised, i.e. some form of forced charge around a low SOC setting point.
The norm for the battery on inclement winter days at the moment is it's holding at about 10%.
In the evening or overnight ( & very occasionally in the day if there's almost no PV output) the battery will draw power from the grid which raises the charge level to ~12%.
Once this charging stops the SOC returns back to 10% in very short order, 10 mins or so
Overnight I've recorded four such events. Evening of Tuesday 6th and morning of the 7th.
Each with charging lasting 1hr during which the data shows 300 additional watts being drawn from the grid over and above the load consumption.
At the end of the hour the import from the grid stops and there's a brief discharge to load from the battery ~ 200 watts in 5-10 mins and the battery is back at 10%. ???
Last nights events were 300 watt import from 2:40 to 3:40 then a second event at 7:55 to 8:55. PV had not kicked in during the latter period due to cloud.
Battery discharge barely registered but within 10-15mins the SOC was back at 10%.
Tuesday evening there were two events at 16:50- 17:50 and 21:20 - 22:20.
So 1.2kWh import from the grid in less than 24hrs and apparently barely anything going back to load.
Clearly these numbers are what I have from the Shine server so not sure just how accurate they actually are.
An additional point to note is that last Thursday, 1st Feb, was a very good PV day which fully charged the battery.
During the subsequent 24 Hrs there was NO import from the grid to the battery.
The duration between these charging events does however seem to depend on how much charge has been available from PV during the day.
So if the battery has received some charge from the PV in the day yet still ends with an SOC at 10% (what charge it had has been used to augment the PV load supply as intended) it can be 8-9 hours before one of these grid charge event occurs. i.e. maybe only one overnight event.
Additional thoughts would be appreciated.
I was in the process of trying to get some more data on the issue but will give you what I have to date.
Firstly @johnb2713
The first thing I did once network connection was established was to check the AC charge setting and it is OFF as you suggested.
I'm now trying to establish if the events I'm seeing are in fact the Growatt "calibration" phenomena which has been referenced in several previous posts, and as noted by @binky, or something more along the lines of what @stuboy has raised, i.e. some form of forced charge around a low SOC setting point.
The norm for the battery on inclement winter days at the moment is it's holding at about 10%.
In the evening or overnight ( & very occasionally in the day if there's almost no PV output) the battery will draw power from the grid which raises the charge level to ~12%.
Once this charging stops the SOC returns back to 10% in very short order, 10 mins or so
Overnight I've recorded four such events. Evening of Tuesday 6th and morning of the 7th.
Each with charging lasting 1hr during which the data shows 300 additional watts being drawn from the grid over and above the load consumption.
At the end of the hour the import from the grid stops and there's a brief discharge to load from the battery ~ 200 watts in 5-10 mins and the battery is back at 10%. ???
Last nights events were 300 watt import from 2:40 to 3:40 then a second event at 7:55 to 8:55. PV had not kicked in during the latter period due to cloud.
Battery discharge barely registered but within 10-15mins the SOC was back at 10%.
Tuesday evening there were two events at 16:50- 17:50 and 21:20 - 22:20.
So 1.2kWh import from the grid in less than 24hrs and apparently barely anything going back to load.
Clearly these numbers are what I have from the Shine server so not sure just how accurate they actually are.
An additional point to note is that last Thursday, 1st Feb, was a very good PV day which fully charged the battery.
During the subsequent 24 Hrs there was NO import from the grid to the battery.
The duration between these charging events does however seem to depend on how much charge has been available from PV during the day.
So if the battery has received some charge from the PV in the day yet still ends with an SOC at 10% (what charge it had has been used to augment the PV load supply as intended) it can be 8-9 hours before one of these grid charge event occurs. i.e. maybe only one overnight event.
Additional thoughts would be appreciated.
How would that happen? Once it hits 11% the BMS switches it off. Having the inverter decide to charge the battery even though AC charging is switched off is a very bad idea, potentially dangerous.
I have seen that happen with a Solax inverter I installed some years ago. During some very dark short winter days it seemed to use a trickle of stored energy dropping soc to around 7%, it then took ages, as in days, to trickle charge the battery back up to above 10%, with some sunnier weather, and kWh of solar being sent to the grid. Very annoying. On advice from Solax soc was set to 16% to prevent it happening again. Nice thing about the Solax app was setting the battery to force charge from the grid was very easy, which is what we did to get it up and running properly again. Not had the same problem since.
My question though is how can it get below my shut off SOC i.e. my Growatt stops the battery at 10%, it's unable to discharge further, the BMS is protecting the cells. How can it continue to discharge? In round figure it would need to consume 210w of self discharge / BMS consumption to drive it down there which just does not happen. Further to the above for the inverter to decide to charge the battery even though AC charging is disabled is a definite no no in my book.
It shouldn't, but, that battery was far smaller than yours, and was fitted roughly 5years ago. I suspect the software has been changed since to prevent it happening.
David_1224
Active member
So @johnb2713 from above comments you are saying the hard deck for your Growatt is 10% and that's set by the BMS.
Are parameters for the BMS accessible anywhere?
Looking in the control panel from the Shinephone app I don't see anything that seems to relate.
I've gone back to check the detailed SOC data on mine and I need to correct what I've posted previously.
Prior to the grid charge events I've noted it appears that the SOC actually drops below the 10% level. Data indicates 9%.
Does this suggest that what I'm actually seeing is a forced charge along the lines of that posted from @stuboy above?
It would also seem to fit with no events being recorded when the battery has received a decent charge from the PV.
i.e. nowhere near a trigger threshold.
Are parameters for the BMS accessible anywhere?
Looking in the control panel from the Shinephone app I don't see anything that seems to relate.
I've gone back to check the detailed SOC data on mine and I need to correct what I've posted previously.
Prior to the grid charge events I've noted it appears that the SOC actually drops below the 10% level. Data indicates 9%.
Does this suggest that what I'm actually seeing is a forced charge along the lines of that posted from @stuboy above?
It would also seem to fit with no events being recorded when the battery has received a decent charge from the PV.
i.e. nowhere near a trigger threshold.
Hi David,
The parameters for the BMS are communicated from the inverter:-
The Load First - Discharge Stopped SOC being the one.
If I switch AC charge off or the time window for AC charge, the inverter will not charge the battery no matter what teh SOC is.
David_1224
Active member
Thanks for the reply John and sticking with me through this.
What are you using to access these settings?
The ShinePhone app only seems to give a limited subset, via the plant control tab, of what you're showing above and I haven't found an "advanced settings" option that might open up more parameters.
What are you using to access these settings?
The ShinePhone app only seems to give a limited subset, via the plant control tab, of what you're showing above and I haven't found an "advanced settings" option that might open up more parameters.
No problem, always happy to help.
Web portal
https://server.growatt.com/index
I prefer the above portal, the app is not so good, portal isnt brilliant but it is easier.
David_1224
Active member
Thanks again John.
I've accessed the portal and made a change to the Discharge Stop SOC.
I'll give it some time and report back when I have some more data.
I've got an idea of what's happening but need to see what happens with the change first.
I've accessed the portal and made a change to the Discharge Stop SOC.
I'll give it some time and report back when I have some more data.
I've got an idea of what's happening but need to see what happens with the change first.
Awaiting to see what you find
David_1224
Active member
OK
Adjustment of the Discharge Stop SOC setting hasn't worked in quite the way I'd hoped but has provided a bit more of an insight into what's going on.
Yesterdays adjustment was simply to increase the Discharge Stop SOC from 10% to 12%.
The hope was that the SOC limit, which triggers force charge of the battery, was a fixed level and that protecting an additional 2% on the battery charge would extend the time it took for the charge to fall to the trigger point. i.e. provide greater head room above the force charge point.
Unfortunately it appears that rather than being a fixed % value its a fixed % below whatever the DS SOC is set to.
So before the change the event sequence was;
Discharge stopped at 10%.
Battery would loose charge until the charge level reached 9%
Force charge would kick in and trickle charge at 300W
When the charge reached 13% and force charge would then stop.
With the DS SOC set to 12% the sequence is simply shifted up 2%, force charge triggers at 11% and charging stops stops at 15%.
Repeats as soon as charge level returns to 11%
Net effect is that the grid charge events continue to take place at roughly the same frequency.
It does raise a question however to any other LI battery users out there.
Is the loss of charge I'm seeing, ~ 1% over 4-6hrs at the ~10% charge level, normal or greater than would be expected?
There's no recorded drain on the battery from the recorded data so apparently it's just charge loss.
The other thing that comes out of the exercise is that if, as it appears, this is quite rightly a BMS sequence to protect the battery from being fully discharged the implementation is not optimised to running in load first priority.
As noted the battery gets charged to a level 2% above the discharge stop SOC.
As soon as the force charge stops the inverter sees the battery is above the DS SOC and immediately discharges the excess back to load.
The battery is quickly returned to the DS SOC level which is again only 1% above the force charge trigger.
That's not a very efficient 2% contribution to load. Watts in to Watts out makes it (relatively) pricey.
It would be much better to have the extra 2% as buffer from a force charge than convert back to power for the load. (needs a better algorithm)
I appreciate that as longer, sunnier days come along this will probably be insignificant in the grand scheme of things but it's still a bit annoying.
Could be a bit more efficient and make winter days a tad more palatable.
I've looked in inverter advanced settings an there doesn't appear to be any other parameter(s) which would impact the BMS routine.
Adjustment of the Discharge Stop SOC setting hasn't worked in quite the way I'd hoped but has provided a bit more of an insight into what's going on.
Yesterdays adjustment was simply to increase the Discharge Stop SOC from 10% to 12%.
The hope was that the SOC limit, which triggers force charge of the battery, was a fixed level and that protecting an additional 2% on the battery charge would extend the time it took for the charge to fall to the trigger point. i.e. provide greater head room above the force charge point.
Unfortunately it appears that rather than being a fixed % value its a fixed % below whatever the DS SOC is set to.
So before the change the event sequence was;
Discharge stopped at 10%.
Battery would loose charge until the charge level reached 9%
Force charge would kick in and trickle charge at 300W
When the charge reached 13% and force charge would then stop.
With the DS SOC set to 12% the sequence is simply shifted up 2%, force charge triggers at 11% and charging stops stops at 15%.
Repeats as soon as charge level returns to 11%
Net effect is that the grid charge events continue to take place at roughly the same frequency.
It does raise a question however to any other LI battery users out there.
Is the loss of charge I'm seeing, ~ 1% over 4-6hrs at the ~10% charge level, normal or greater than would be expected?
There's no recorded drain on the battery from the recorded data so apparently it's just charge loss.
The other thing that comes out of the exercise is that if, as it appears, this is quite rightly a BMS sequence to protect the battery from being fully discharged the implementation is not optimised to running in load first priority.
As noted the battery gets charged to a level 2% above the discharge stop SOC.
As soon as the force charge stops the inverter sees the battery is above the DS SOC and immediately discharges the excess back to load.
The battery is quickly returned to the DS SOC level which is again only 1% above the force charge trigger.
That's not a very efficient 2% contribution to load. Watts in to Watts out makes it (relatively) pricey.
It would be much better to have the extra 2% as buffer from a force charge than convert back to power for the load. (needs a better algorithm)
I appreciate that as longer, sunnier days come along
this will probably be insignificant in the grand scheme of things but it's still a bit annoying.Could be a bit more efficient and make winter days a tad more palatable.
I've looked in inverter advanced settings an there doesn't appear to be any other parameter(s) which would impact the BMS routine.
Nice theory.......
That is really odd behaviour, mine doesnt do that, I have the same battery with an SPH6000 inverter
Mine will sit there seemingly for ever at the same SOC, it will not go below the discharge stop %
Software update on the inverter?
It's not acceptable and needs to be sorted.I appreciate that as longer, sunnier days come along
Could be a bit more efficient and make winter days a tad more palatable.
Could you post the list of settings what you have, see if we can spot anything.
David_1224
Active member
Okay John settings as requested.
The ONLY thing I can see there which shouldn't have any issues are the AC charging slots, all at 00:00:00 to 00:00:00 they are enabled, I know AC charge is off but I wonder if there's a bug in the software and the 00:00:00 to 00:00:00 is 24 hr charging? I seriously doubt it but just for the hell of it, disable all 3 of them.
David_1224
Active member
Funny that.
It's the only thing that I could see as well.
I've flipped them to disabled and will see what we get overnight.
Not too hopeful as I'm starting to think the charge loss may be the bigger issue.
It's the only thing that I could see as well.
I've flipped them to disabled and will see what we get overnight.
Not too hopeful as I'm starting to think the charge loss may be the bigger issue.
David_1224
Active member
Well shouldn't be surprised but flipping those parameters to "disabled" made no difference.
Worryingly it also feels like the time between events is actually getting shorter.
Overnight I recorded 3 hours and 4 hours between grid charge episodes suggesting the loss of charge from 12% through 11% is getting shorter.
John
If you get back to this post do you have any data on how your battery performs around the SOC level?
I got the impression, from what you've posted on other threads, that you're predominantly using off-peak grid to charge your battery.
I'd have thought that the way you're using your system you wouldn't have much time when your battery would be sitting at or about it's minimum SOC.
For instance in my case when the PV has injected enough charge to get me to > 90% I'll get through more than 24hrs without seeing any input from the grid.
Monday was just such a day.
Battery was 100% by late afternoon.
Covered the load through the night and had sufficient to last through to getting some more PV input through mid-day Tuesday.
So this, plus minimal PV input Tues pm, covered load requirements through to about 20:00 Tues evening.
So then I didn't record any grid input until around 00:00 - 01:00 Wednesday. (12% at ~ 20:00 decay through 11% around midnight)
It would be good to know if my (no load) discharge rate is typical or do I have an issue.
Alternatively am I just expecting too much and am being greedy.
Worryingly it also feels like the time between events is actually getting shorter.
Overnight I recorded 3 hours and 4 hours between grid charge episodes suggesting the loss of charge from 12% through 11% is getting shorter.
John
If you get back to this post do you have any data on how your battery performs around the SOC level?
I got the impression, from what you've posted on other threads, that you're predominantly using off-peak grid to charge your battery.
I'd have thought that the way you're using your system you wouldn't have much time when your battery would be sitting at or about it's minimum SOC.
For instance in my case when the PV has injected enough charge to get me to > 90% I'll get through more than 24hrs without seeing any input from the grid.
Monday was just such a day.
Battery was 100% by late afternoon.
Covered the load through the night and had sufficient to last through to getting some more PV input through mid-day Tuesday.
So this, plus minimal PV input Tues pm, covered load requirements through to about 20:00 Tues evening.
So then I didn't record any grid input until around 00:00 - 01:00 Wednesday. (12% at ~ 20:00 decay through 11% around midnight)
It would be good to know if my (no load) discharge rate is typical or do I have an issue.
Alternatively am I just expecting too much and am being greedy.
My Growatt battery is usually depleted by mid morning if there's little solar around. Once it's down to minimum it stays there until 23:30 when the AC charging is scheduled. This is typical:
