Odd battery behaviour

SD_DRACULA

This is the second time I am seeing my inverter charging the battery to 20%, let's it go down down to 10%, charges it back to 20%, and so on, from the grid and without me telling it/setting it to that.

The min charge is set to 10%

Anyone else came across this and any idea how to stop it? I feel like it is putting needless tress on the battery.

SD_DRACULA

Inverter is a solis rhi-6k-48es-5g on FW 340022 and the battery is a 5kw puredrive DC

MAULBROOK

Its probably forced charging, I dont know how to change it. Give Darrell a call he should be able to sort it in seconds

jkforde

if you get it sorted could you update us for future reference!, I've got the same inverter.

have you tried a full system shutdown and restart?

SD_DRACULA

Both overdischarge soc and force charge at 10%, he doesn't know why, he said he'd get Solis to update it.

Thought it's doing it maybe because of the stuff I am running directly from the socket connected to the inverter but that makes no sense since it didn't do it until now.

I'll bump up the overdischarge SOC to 12% that might do it for now but shouldn't have to

SD_DRACULA

https://www.boards.ie/discussion/comment/118044879#Comment_118044879

Avoiding that since I got my network gear hooked up to the inverter directly and it's a royal pain to reboot everything.

jkforde

send your inverter & logger SN to euservice@solisinverters.com, they're very responsive (Radosław is good).

they'll log in and check, and may even update the firmware for you

SD_DRACULA

Set the overdischarge to 12% and it stopped doing it

I'll get onto Solis for that FW update too

reklamos

I have this with my inverter also. Firmware upgrade did not sort it out. What I did notice that it only happened during autumn/winter and seems to be happening in the mornings. It has never happened in summer. The inverter would force charge battery a bit and then discharge and would keep on doing that for a while and then would stop. The other way to stop it is to reboot inverter or the battery. I do not have an answer why this happens but it is battery related. It has happened at the end of September this year. I've pulled the graphs and one thing that does stand out is that the cell temperature has dropped to 17-18C . It seems like inverter is exercising the battery to raise the temperature but 17C is not low temperature. I am waiting for it to happen again but the temps are staying above 20.

You can see charge spikes start happening at 6am and then there is discharge and it keep repeating it.

SD_DRACULA

I'm not seeing the battery temp but the attic ambient temp was just above 20 degrees so in no way too low temp.

Stopped doing it as soon as I bumped the overdischarge to 12%.

I wonder if it somehow discharged to just under 10% and then it forced charged but then again why do it a few times.

reklamos

When I had this first time I also bumped the the values up but it did not stop it from happening again. The ambient room temp is also at 20 and you can see from the graph that some cells from other batteries are reading 20-21 degrees. That one battery is always reading lower temps compared to other two even though they are on top of each other. I would say the temp probes are not accurate. I am just waiting for temps to drop again but we've been blessed with unusually warm weather. There is no harm to talk to support but the last time I reported this, it went nowhere. Since I have logging now I just need more data. :)

SD_DRACULA

And it was also draining it with more than the house load at the time.

For example house load was maybe 500w and it was draining at over 1kw but then as soon as I bumped it up it went down to the real load value.

reklamos

Yes, exactly same behavior it was force discharging and dumping into grid or in my case into water diverter.

SD_DRACULA

Let's post here if we find anything, we have different batteries so that rules that out, must be the Solis

reklamos

Sure will do. Maybe need to pull more data from Solis. Not only that our batteries are different but also inverters. I see your one is 5G and mine is not and also we are on different firmware versions.

SD_DRACULA

Come to think of it I think originally the overdischarge was set at 15% and then I set it to 10% myself.

SD_DRACULA

Started happening again and Solis support are getting thick with their replies:

​Your system is setup exactly to do what its doing. Please contact your installer if you have further questions.  

reklamos

Mine have not done it so far. I had no luck with support couple years ago also.

Mickeroo

I noticed mine doing that last winter during colder weather, I think it's to protect the battery. No idea if it can be turned off.

Does anyone know if there's a way to stop it going below 20% to begin with?

SD_DRACULA

Did it about 4 times today already

@Mickeroo you would go to the battery settings and change the overdischarge to 20% and hope for the best, inverter seems to be ignoring the force charge of 10% and charges at 12% anyway.

@Mickeroo do you have anything running off the AC backup, seems to happen to us folk which do

Mickeroo

https://www.boards.ie/discussion/comment/118123811#Comment_118123811

Nothing running off backup for me though it always shows it as consuming a few watts on the logger for some reason (110w at the mo).

I haven't had the forced charge happen yet though a very strange thing happened yesterday where my total consumption (since system install) doubled on the portal and my consumotion for the day was way more than what it actually was, It also no longer shows the battery percent in the little graphic (but the graph still has it). On the inverter itself everything looked fine so I guess it was an issue with the logger or something on ginlong's end.

All the total figures on the right are double what they were the day before (eg Total consumption is now 12MWh+ when in fact it was only 6MWh+ before):

reklamos

As I have not experienced it for a while and normally by this time of the year I would have had this multiple times, I think I have theory.

After reading/watching multiple articles/videos about LiFePO4 batteries I decided to bump my minimum SOC to 30% during dark period as we do not get enough sunlight to get it charged 100% anyway. According to the info that I've seen it is preferred to not leave batteries at minimum SOC for long periods of time. So I thought 30% is going to be a sweet spot. Now since this change I have not seen this charge/discharge behavior that I had last 2 winters. It is still a theory and will see how long it will hold. I will reduce SOC back to normal in spring. I'll let you decide if you want to try it. :)

SD_DRACULA

You could be right. I bumped it up to 15% and it stopped doing it straight away.

Was also chatting to the installer and he said to have grid charging turned on - this part doesn't make sense since surely this is part of the reason it pulls from the grid

Look at the battery voltage, the 4 spikes is when it bumped itself up to 22%, then went down to 12% and so on.

However WTF did it go down to 48v? I think the 12% SOC was total BS and went down past it, after the spikes stopped is after I changed overdischarge to 15% and it stayed at around 50v

I am guessing voltage/SOC don't quite line up and it knows the voltage is too low so it pulls from grid, maybe?

I think you're spot on with leaving a higher SOC in winter too

Mickeroo

Do you have a pic of where you can set the minimum SOC? Was up at the inverter yesterday and couldn't find it. I'd say I must have an older version of the software on there as I didn't see any settings for charging from the grid either.

reklamos

My understanding is that charge from grid is required for FOC otherwise inverter will not charge the battery when it dips below FOC.

SOC is calculated using Coulomb method and not Voltage method as voltage fluctuates greatly during charge/discharge and would be unreliable.

I have looked at battery voltage in my setup and it does dip below 48V during normal operations when there is a surge in power required from battery but it does recover. Looking at the stats now I did noticed that the last 2 times this happened the voltage dropped close to but not below 48V. When all is ok the voltage is ~49V. Since I have raised SOC to 30% the voltage is ~49.5V. As I wrote before this only happens during Autumn/Winter and my only logical explanation is that this is temperature related. Dip in temperature lowers battery voltage by ~0.5V close to 48V and that is enough for inverter to go into panic mode.

SD_DRACULA

https://www.boards.ie/discussion/comment/118127539#Comment_118127539

I think it is when you go to battery storage select, you select Self use, and maybe when you click into that you can set the values there. You're better off looking up the manual as they differ a lot.

https://www.boards.ie/discussion/comment/118127702#Comment_118127702

For me it is hovering at 50v with SOC 15% for today, 13-15c temp attic temp.

reklamos

https://www.boards.ie/discussion/comment/118127539#Comment_118127539

got to advanced settings>storage energy set>Battery select. Select your battery then as you apply seeting you will get options for SOC and FOC

reklamos

https://www.boards.ie/discussion/comment/118128841#Comment_118128841

I think Solis is over cautious. I have looked at my battery information and discharge voltage can go as low as 45V. The battery shutsdown only if it drops 44.5V. The settings on Solis is showing battery undervoltage is 46V but it has never dropped that low. Also when Solis starts this charge/discharge cycle it does not log any warning or errors.

SD_DRACULA

Did it again just now twice so definitely something wrong with the inverter I think (software I'd say)

So I had the overdischarge set to 15%, it bumped it from the grid to 25% then back to 15% twice.

Then I went to the inverter and clicked 15% overdischarge again, saved and it stopped doing it.

It did think the SOC went to 1% which is BS, as the voltage went no lower than 47.1v so the calculation must be way off and then it charged from grid to "10%" and voltage 51.5

Something to do with wrong voltage/SOC

SD_DRACULA

If battery not charged for long time but got charged to 70% today from PV....

reklamos

Interesting. Yuor inverter bumps it up by 10%, mine only bumps it by 1% then force discharges then does it again.

Thankfully it is still has not done it since I've raised ti to 30%. Before it would do that at least once a week. What is is DOD for pure drive batteries? I could not find that info on their page.

SD_DRACULA

90% is the DOD.

The force charge value (10%) is actually the amount to charge by not when the battery reaches this SOC it seems.

I think it charges based on voltage and not on SOC, which makes the overdischarge value a bit useless.

I can see that lowest voltage is set to 44v when selecting the puredrive profile which it never got to.

reklamos

I think we can be sure that there is no definite answer as it varies between firmware versions and is very poorly documented. I do not think what we are seeing is force charge. I had it before and it actually logs it as a warning message 'ForceCHG-BMS' on the inverter. I have not seen this or any other message during this up and down behavior. What we are seeing is not documented or logs anything, probably some engineering 'feature' that Solis has added for some reason.

graememk

I am not sure what protocol the puredrive uses, but a lot of them use the SMA protocol.

SMA CAN protocol.pdf

There is parts of it where the BMS can actually request a charge too, from whereever, but its usually the Grid!.

How deep the rabbit hole do you want to run lol.

SD_DRACULA

Still happening and it is p***ing me off now.

Limit set to to 20% and keeps charging itself randomly i.e. wasting power.

Solis support are utterly useless so they won't do a thing.

I explained to them that if I go to the battery settings and just apply them again it stops doing it, in other words something is wrong plain and simple.

Quite obvious the inverter is reading the voltages wrong and panicking:

Was thinking of just setting the force charge to 1% instead of 10% but not sure what effect that might have if the battery has an actual low voltage

Jonathan

https://www.boards.ie/discussion/comment/118234647#Comment_118234647

We have same setup (Solis Inverter and PureDrive battery) and I haven't seen this happen. What f/w are you on?

SD_DRACULA

340022 and it never did this during the good months.

Also do you have anything hooked up to the AC backup port? I have my network gear connected to it so I assumed it might be this but I seriously doubt it.

Jonathan

https://www.boards.ie/discussion/comment/118235404#Comment_118235404

I'm on 350022. No, nothing connected to backup load.. though I might put a repeater up there as WiFi signal poor.

SD_DRACULA

Something dodgy going on for sure. I switched off the battery and all the AC backup connected stuff lost power (don't see why this happened as grid was still up, maybe stupid design).

Then turned on the battery and it said battery 0% (after being 20% before being switched off) it charged it to 10% and stopped doing the weird grid charging.

I also removed anything from the AC backup and switched the option off completely, it is pointless since in winter the battery is mostly drained and if a power cut happens it won't power anything anyway. At least I will know if it is related to that if it doesn't happen again.

I asked Solis for a remote FW update and never heard back.

irishchris

https://www.boards.ie/discussion/comment/118236187#Comment_118236187

The Solis is DC powered so once battery turned off if there is no solar PV then it will shut down irregardless of grid

SD_DRACULA

https://www.boards.ie/discussion/comment/118236723#Comment_118236723

Ok fair enough, that must have been what happened, I assumed if you have AC backup and grid connected it will continue to pull from grid to keep AC backup alive and only revert to solar/battery if they are available.

SD_DRACULA

So Solis finally got back to me with this:

yes so the battery management system (inside the batteries) would do estimations of SOC and after long periods of hovering at 20% odd they will be wrong.

Resetting it could help the batteries "find themselves". 

Your batteries are not getting much energy at all. I would recommend either shutting them down during winter periods, or applying for a cheaper tariff and fully charging them during that period.

So it looks like my 20% and 48v readings from the readings of the inverter were bogus and the battery needs to be reset every now and again if not getting charged regularly. Shame that I fell for the smart meter scam and can't get day/night anymore

reklamos

This is strange, the capacity value is provided by battery through CAN. The inverter should not try to guess it. Maybe check your battery firmware. As @Jonathan has same battery. Try to compare them. My capacity never dropped to 0% when I was having these problems.

Since I have set backup to 30% it never done this. As you are using AC backup, set your soc to 20% and then set backup to 25 - 30%. Just make sure that you allow to charge from grid in backup menu. This way you will have 5-10% in case of power cut and also it will not allow battery to drop low. One thing to note, you may notice that the battery does drop below 30% during dark periods, this is normal. In my case once it drop to 27%, it charges from grid to bring it up to 31%.

SD_DRACULA

I cannot see any way to check FW of the battery, maybe some hidden Solis modbus registers?

Only seeing this:

And over discharge/force charge values are wrong also, not what I'm seeing on the Solis setup screen.

I'll leave the AC backup off for a while, see how it behaves.

Jonathan

https://www.boards.ie/discussion/comment/118239921#Comment_118239921

I think the difference is that I'm charging on night rate and discharging during the day. This means that the battery is never sitting at low SOC for long periods of time.

reklamos

https://www.boards.ie/discussion/comment/118240463#Comment_118240463

Oh yes, completely forgot about that.

https://www.boards.ie/discussion/comment/118240053#Comment_118240053

I do not think you will see firmware on Solis, you should get that from battery itself. At least this is how it is with Pylontech. But it is odd that the values set on inverter are not reflected in the app. As I wrote before you could try to set backup, configure to allow charge from grid and see if it actually works. If it does then you could use it as your safe guard as it seems that FOC do not work for you. The backup could work for you as FOC and SOC in one. It is a simple enough test. Let say your inverter is showing battery as 12% now. You configure your backup as 20% and once applied you should immediately see battery charging to ~20-22% and then stopping.

SD_DRACULA

Ok I enabled this, and set it to 20%

And it started charging, from 12%.

Question is, when it gets charged by PV to over 20%, will it send power to the house until it gets to 20% or it will save all for AC backup?

Ac backup is disabled now, so it should not go below 20% in theory

reklamos

20% is your bottom line it will allow to use 20-100% for house load. Once the battery discharges to 20% it should stop and keep it at that. The battery will lose charge over time even when there is nothing connected to it depending on room temperature. But that should be within 1% in 24hours. If it losing more than something is not right. As I wrote, inverter will allow to drop charge bellow 20% but in my case once it dropped by 3%, it started topping it from grid.

SD_DRACULA

Thanks for the suggestion, will keep an eye on it but I suspect it won't make a difference if what Solis said is true, if it starts to drift due to a low charge for an extended period and the only way to bring it back is to power cycle the battery.

That would indicate a crappy BMS inside the battery in my opinion.

reklamos

https://www.boards.ie/discussion/comment/118243482#Comment_118243482

It would be interesting to connect directly to the battery, log the data and see what it is doing. This could give better insight and maybe it is issue with BMS or comms between in battery and inverter. Unfortunately I can not help much here as I do not have puredrive. On pylons I do have rs485 and rs232 and have logging and see everything. The concerning thing is that battery goes to 0% as you noticed after powering it off/on. But even if inverter is not reporting properly the battery itself should shutdown before going that low independent of inverter.

SD_DRACULA

Basically the battery readings of the inverter are still a "mistery" according to Solis - which should not be the case

I don't think it was actually 0 anyway, if the voltage was to be trusted it got as low as 47.9 and the lowest limit is 44v for that battery according to the settings on the inverter when you select puredrive form the list - but yes it would be nice to be able to monitor the real battery values directly via rs485 or similar.

I asked them a while back how can the SOH go to 97% in less than 6 months and got an answer like that's still experimental/not an accurate science/it's an estimate and similar non-sense.