Carrara Frederic avatar image
Carrara Frederic asked

Victron Lithium Battery With ESS not cycling fully

Hello dear team ! I've an installation at home with MutiPlus 48/5000, Fronius Primo on AC Out, Color Control GX, Ve.Bus BMS and Battery Lithium CB 300AH Victron.
The system is functionning with the ESS Mode and with not BatteryLife.
All is functionnig good but impossible to go down of 60% SOC and 51V approximatively even if i put 20% of discharge max on VEGX / ESS/ Max Discharge.
All firmware are the last. And in programmation i make the ESS standard options with lithium Battery Victron.
Can you help me ? Do you have a programmation more advanced than could use ?
Best regards

ESSLithium BatterySOC
1 comment
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k2aab avatar image k2aab commented ·

Hi i have a similar issue, multiplus 2, LG Chem 6.5 with colour control, my solar is a parallel system. System has been in a week, working well, setup for optimised with battery life, active SOC is 15% however it's been cutting off at about 40% capacity remaining, today at 47%.

The battery is getting a good charge every night via scheduled charge to 95%, hence the active SOC is staying low but i'm not getting close to the 15%.

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2 Answers
wkirby avatar image
wkirby answered ·

What are your "Sustain Voltage" and "Dynamic Cut-off" settings for ESS Assistant?

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k2aab avatar image k2aab commented ·

I'm thinking my system needs a tweak around these values as per:

Do you know if there a way of accessing the assistant via a com port without having to buy a Victron MK3 USB converter?

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Try using the remote VEConfigure feature.

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k2aab avatar image k2aab commented ·

I have the same issue and i think you are right with your suggestions to what it causing this issue, i have commented on another thread:

As per the Victron Doc for LG Chem and Multiplus i have my Sustain Voltage set to 50V, however in the same doc it tells you not to change the Dynamic Cut-off values/curve, nor change the restart value. However i think it's these dynamic cut off values that are cutting in before the sustain voltage and or the SOC limit. Thus significant charge is being unused.

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andre avatar image andre commented ·

I have same set-up with Pylontech batteries except I selected Optimised (with battery life) and batteries are only charged by Solar.

I have same limit imposed on selected Minimum SOC (set at= 25%) by the system determined Active SOC limit.

Active SOC limit is lower when fully charged in day (55%) and higher when not fully charged (60 to 65%). This effectively ensures batteries charged, by Solar to 50 V at least once per day!

I suspect this will change when I add 3 Kw solar inverter - next week or when better weather!

Very clever algorithms for Self-Consumption - with battery life!

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k2aab avatar image k2aab andre commented ·

@Andre Interesting to see how you get on, I’m charging every night from the grid at off peak tarrif to 95% SOC. So my dynamic min SOC is 15% (also using with battery life) but the lowest I’ve ever seen is 37% SOC when the inverter stops. I think it’s to do with the discharge curve. Lithium batteries are expensive and I want to use all the capacity, not just 60%

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andre avatar image andre k2aab commented ·

Howzit! Yes...but SOC is complex calculation and at best a rough estimate unless all input and output disconnected and battery at rest for some minutes. Also want expensive batteries to live long. Maybe worth calculating how many kW you moved from battery during discharge to see what percentage of capacity you actually drained.

I added 3 kW Sunnyboy to AC Output 1 of MultiPlus yesterday afternoon. Batteries rapidly charged and already Active SOC limit is down to 50%.

CCGX displaying strange numbers...still trying to see if I can correct it. I have been having issues with CCGXs...


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andre avatar image andre andre commented ·

Howzit @k2aab, The CCGX does not provide Consumed Amphours in the Battery Summary widget in my setup. Does your system capture this parameter?

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k2aab avatar image k2aab andre commented ·

@Andre Interesting thought, I've used the VRM portal today to look at what came from battery, adding the figures i got 2.67KWh. I started with 95%SOC and today it stopped inverting at 45%. If I then take the 5.9KWh (usable of the 6.5 LG Chem) that give me 2.95KWh. I think that's fair enough, and shows the system and battery are sort of in sync, so I'm still loosing 30% capacity based on my active 15% SOC limit. I'm sure this is to do with the cut off values. I've logged a call with LG Chem. I've also found that Solax set the cut off voltages much lower than Victron.

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andre avatar image andre k2aab commented ·

@k2aab Seeing that you charge from AC and not Solar, you don't need With battery life. If you disable this the batteries should discharge to the Minimum SOC that you select.

The fact that the With battery life algorithm limits the extent of discharge implies that batteries are not fully charged during scheduled charge - have you tried longer charging period?

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k2aab avatar image k2aab andre commented ·

@Andre I'm in the UK, winter so i'm not getting enough Solar at the moment to charge hence the AC charging so just making the most of my off peak tariff. Even with no battery life it fails to discharge past about 40%. Yesterday i dropped each of the cut off voltages by current by 1 volt each, now they system discharges to about 20%, not quite the Min SOC but very close. So I'm now positive these setting stop the inverter too early for a ESS system. I also feel the Sustain voltage is too high at 50.0 volts as per Victron doc

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andre avatar image
andre answered ·

@k2aab Ha! I am in Africa, so much sun its scary!
If you discharge batteries to 40 % as opposed to 20 %, I suspect they will live longer.
Here, we have no differential tariff for peak & off peak and only get half of what we pay when legally feed into grid. You are tied to ESS because of your battery type.
My Active SOC is decreasing by 5 % each day as I more effectively charge batteries from sun.
Explained here:

I am new to Lithium batteries but suspect that you may need longer charge period (high V but low A) to get batteries to real 98 % charge and this may allow then discharging to 20%.

Instantaneous (calculated) SOC maybe somewhat different to actual chemical energy available in battery. You push batteries hard they may die young.

What is odd about the original question is that With battery life apparently not enabled!

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