Plonkster, this is EXACTLY what I did, small battery bank etc right down to the 95% min SOC limit.
Everything happened exactly as you described, TTT actually helped me sort it out. This makes sense now thank you
I however experiences similar scenarios as what he describes above.
Sometimes I will have much more PV available that what is needed, yet this will be diverted to charging batteries only, leaving the house to run from the grid whilst there is plenty for both.
I also don’t get this.
Case sample.
Min SOC is set to 80%, system elects to only charge the batts with very little from solar:
So I drop SOC to 75% … walla, sorted:
7.2kwh lithium bank i.e. 16 x 150ah cells so small bank it is not. Daly BMS … yes, I question that definitely.
And the tappets are open ito charge amps on the lithiums.
Previous bank was 16 x Trojan T105RE’s, also not “small” anymore.
Yes, we get that. “Very high” is 90% and above. I can see where the batts are getting full i.e. amps going into the batts drop and drop. The pic above, the 82%, them batts are NOWHERE full. I can drop the loads and the batts will grab the amps again.
And it is not a “small” bank anymore as the amps are near full taps, not like a small Torjan bank with low charge amps.
I get it that when the SOC is in the 90’s and the volts vs SOC, but the BMV is close as damn to keep the SOC measurement in line i.e. 100% SOC correlates with very little amps going in, starts at 96% upwards.
BUT … Daly is what I’m currently questioning AND it is not interfacing with the system.
BUT … stuff has been improved on the Venus software, me having been a Release Candidate user having skip-read about the changes one has to look out for on new versions.
Maybe I’m missing/misunderstanding a salient core point, most definitely that does happen, but the above post, that is absolutely new for me, and it happens a bit, where the MPPT goes to 469w where the actual potential is 2558w.
See, now it behaves as expected:
Feedback due to induction pate being used somewhere in the house.
Note the “ESS #1”. That means “feed-in” is disabled. When you see that #1… no power is making it from the DC bus to the AC bus. The inverter component is disabled. It won’t work. Forget it. Die kraan is toegedraai.
But why? Who decided to turn off that tap when there is so much solar potential?
The blerrie Daly BMS interfering maybe?
Let me explain something. With that switch turned off, the inverter draws around 12W of power. With that switch on, it draws around 35W of power. It is the same tap that is closed at night when you reach MinSoc. What would you prefer at night when the battery is already low, 12 or 35? 
#1 means your SOC is lower than the active SOC (either the batterylife one, or the one you set). It is that simple…
There is an additional issue I see. This tends to plague people with lead acid batteries that also don’t have a BMV.
The issue is SOC drift. It happens when the estimated SOC is lower than the actual SOC of the battery. The estimated SOC, for example might be 80%, while the real SOC is in the mid 90s. As we all know, a lead acid battery in the mid 90s does not accept much charge current, and the voltage rises easily. Add in even a moderately high MinSoc, and it all ends up in deadlock.
This is usually worse in systems without a BMV, because the default charge efficiency in the Multi is set to a very pessimistic number (there is a spot in VE-Configure where you can set it). This means the Multi tends to underestimate the SOC. The BMV also has a reset feature (high enough voltage, low enough charge current) while the Multi does not…
Even Lithium batteries does not always escape this issue. BYD and BlueNova batteries are not good at measuring low amounts of current… so the SOC tends to drift if you spend long periods at low charge or discharge currents.
Ok, let me get my head around this. Bare with me.
Then maybe, take this case of Min SOC 80%, at 81-83% SOC, and not always, system decides to go into ESS#1 mode.
That with a household load of 4.5kw, peak panel potential of 2801w from panels, system decides to stop feed-in, because of the SOC?
Does not do it all the time nor can I make it to happen on demand.
But it does happen, perfect bell curve ito solar production, then wham, bare minimum peak times, then after a number of minutes continues, worst case maybe an hour, before it decides to carry on using full panel potential.
Sorry, but I don’t “get it” as there is a BMV in play, no lead acid and the lithiums still has a lot of potential to take more amps to charge.
Download your data and prove it…
The BatterLife state machine is extensively unit-tested. I won’t say there is no bug in it… but there is certainly no obvious bug in it. It’s working fine for thousands of systems.
The fact that you adjust MinSoc with cron jobs may well have something to do with it. There is hysteresis in many of the switching points (eg you need to move up 3% before it will go back into self-consumption mode). With a battery at 82% (for example), lowering your MinSoc from 85 to 80 is not going to be enough to kick it back into self-consumption.
If you download your data from VRM… you may well see the reason clearly.
Using Cronjobs upping the SOC on the lithium bank was stopped. Worked on the lead acid, not anymore. Goes for Eskom to re-charge, just about all the time. I have to do it manually, if SOC is min 1% higher to the level I must adjust it to, like 81% before I set it to 80%, or else Eskom is used.
Take the real-world example, as per pics above, Min SOC was set to 80%.
At SOC of 82%, ESS#1 was enabled somehow.
If I see it, I drop the Min SOC manually from 80% to 75%, instantly system starts using all the panels again, seconds later I set SOC back to 80%, keeps on working as expected. Each and every time.
Note: The screen shots I have posted above, are seconds apart, per scenario/post.
Here you can see - when batts are full, it never happens:
You’re tripping over the hysteresis. Your test steps clearly shows that.
If you play with it a bit you will get a feeling for how it works. If the SOC is at 82%, and MinSoc is at 85%. This will happen:
However, if you start with an SoC of 84% and a MinSoc of 85%, then this happens:
Why is there a hysteresis? If there isn’t one, then the system starts osscilating on 0.1%. It starts inverting on 85.1% and stops on 85.0%… repeatedly… that is why there is a hysteresis.
1.
I agree and get that IF the SOC is at 82%, and MinSoc is at 85%
But I don’t get is IF the SOC is at 82%, and MinSoc is at 80%
Come to think of it… I’ve had at least one complaint about a related matter. BatteryLife adjusts the MinSoc up by 5% on any day when the battery did not reach a good level of charge. This happens at midnight…
So tomorrow, we have to charge the battery by a whole 8% (the 5% added by BatteryLife, plus the 3% hysteresis) before it goes back into self-consumption. At least one customer thought this could be done better. The problem is, that customer came up with a plan that was rather South African in nature (doing certain housekeeping around 6PM). The trouble is that in places like Germany, in July… the sun sets at 23:30. In some places it doesn’t set at all…
The only thing that would explain that, is if the actual Soc was momentarily lower than the MinSoc at ANY point.
By the time you come to investigate, you may see 82% on the meter NOW, but you may not have seen that it dipped momentarily below 80% 15 minutes ago… are you absolutely sure it did not? Download your data from VRM and prove it… then we can file a bug and fix it.
But as I said, I am pretty damn sure there is no such bug. Because we specifically test the crap out of that state machine to make sure there isn’t…
I get that too … I’m not using BatteryLife …
100% sure of that … How? Because I watch it the whole time, screen is open on my PC.
On top of which, if I see 81% on the SOC, I increase to Min SOC to 80% … so it could not slip past me to go below 80% for 15 minutes if I turn my head for 15 minutes.
I can also state for a fact, on SOC above 90% up to 100%, I have never seen it go into ESS#1 mode either. All the panels can product in the afternoons, with a high SOC is “absorbed” by the house. I even run Scheduled Charging from 4:30pm onwards with low SOC of 15%, to not use batteries, till 10pm, when system must again.
And you know that number is rounded to the nearest percent?
Again. Prove it. Download the data from VRM and show me where. I’m fairly confident there is nothing wrong. I’ve chased down too many red herrings…
Jip, for if it is not, then Eskom kicks in instantly.
In real life I want for 2% above the Min SOC setting.
YES, I 100% appreciate you wasting time on red herrings. And I do NOT want to contribute to that.
I have made the data set smaller, in yellow the point it happened, using the Solar Charger [260]
Battery watts to find them. Cannot upload the file here, so I’ve emailed it to you.
I don’t know what to look for. All seems perfectly normal, bar the fact that the MPPT just throttles.
I’ll also reply here, and apologise for being somewhat unwilling to traverse that rabbit hole again… I see now it may just be a misunderstanding of how things work. The switching point (where the algorithm stops discharging) is “equal or less than”.
The reason why it must include equal is because that makes logical sense. The term is “minimum state of charge”, so if we continue to discharge until we’re under the minimum… then we’ve broken the agreement, we went under the minimum.
So if you set a MinSoc of 80%, then it will stop discharging ON 80%… not below 80% (79.9% for example). It also has to be like this since not all battery monitors give you a number in tenths of a percentage. Some are only up to 0.5%, some only up to 1%. Customers would be very upset if we continued on to 79% when they asked for 80%…
So with that out of the way, I marked the spot where things went wrong for you…
After that, it remained Discharged until it charged back up to 83%.
At 83%, the voltage should not raise easily and the MPPT should be able to go flat out (into the batteries). But we’ve had this discussion offline too… I still wonder why your bank seems to act like that. It behalves like a lead acid bank…
Therein me, questioning the Daly BMS first.
I’m still not 100% clear of what I do to make this happen, for I will switch on 82% to min SOC of 80%.
I’m truly confused, for most of the time it works, sometimes it does not and normally that is at the most upportune moment when I’m nowhere near the system. With an actulal lead acid bank, I never had this.
As there are times when I,m nowhere close to the system and it decides to stick to bare basic minimum watts to do something with the batts, bats are nowhere full, only to jump to full potential power minutes, or worse, hour later.
Those perfect graphs of a MPPT under load for the day, they are a treat for me, like in once in a wide while. Most of the time I get jagged graphs … today was one, but it was the weather.
For as per my reply back to you … why does it not happen later again after I “kick started” the system a bit:
After yellow, I did my “thing” with the SOC.
I’m seeing Jaco on Thursday. I will ask him to try and help explain what I’m missing,
