Upgraded to LiFePo4 battery, Are my settings correct? Also some ESS questions

Question

question

xpatrik asked Mar 6, '23

Upgraded to LiFePo4 battery, Are my settings correct? Also some ESS questions

So a few days ago I switched from my old 14s 18650 li-ion battery (only 18 ah in capacity test) To a 16S 125AH LiFePo4 battery (Build from CALB Prismatic cells). I'm not sure if my charging settings are corret and also the smart shunt settings.

Battery specs:
16S 3.2V - 51.2V
125AH
Charge/Discharge max: 1C
BMS: JK-BD6A20S10P
BMS Cell Over-Voltage Protection: 3.6V (57.6V)
BMS Cell Unver-Voltage Protection: 2.7V (43.2V)

System specs:
Victron MultiPlus-II 48/3000/35-32
Victron SmartShunt 500A
Victron BlueSolar Charger MPPT 150/45 rev3 (6x 285W, 6x 225W panels)
Aliexpress Grid-Tie PVGS 180W (1x 100W panel)
Aliexpress Grid-Tie PVGS 350W (1x 285W panel)
ACS712 30A + Arduino Nano for dedicated DC-System meter
3x DS18B20 Temperature sensors + Arduino Nano for 3x Temperature sensors
Raspberry PI 3 B+ with venus os acting as venus device for victron vrm monitoring

Also some ess questions:

1- What should my grid setpoint be to have the lowest grid consumption without exporting to grid form battery? (Grid export is allowed but dont get paid anything so would like to keep it at 0W)

2- In ess system do the mppts use their charge settings or are they ignored and synced with the multiplus charge settings?

Here are my settings, Tell me if i should change anything or if its good:

Multiplus - Inverter:

Multiplus - Charger:

Multiplus - ESS:

Smart Shunt:

Mppt:

ESS Lithium Battery

shunt.png (24.0 KiB)

mppt.png (45.1 KiB)

inverter.png (2.9 KiB)

charger.png (11.3 KiB)

ess.png (24.1 KiB)

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Modifications Space

Node Red Space

Answer 1 · 2023-03-07T10:13:09Z

Hi @xPatrik

TLDR: settings look fine!

1. Yes ESS grid setpoint of zero makes it so that the system balancing output with loads and solar such that the grid point is 0. That will get you lowest possible grid consumption.

2. I believe they're ignored if they are higher than what is set within multiplus charge settings. If they're lower then they take effect.

In relation to your settings.

BMS: I set mine to 3.6v and 2.8v), however my victron settings should ensure that those are never reached.

Inverter I'm even more conservative but for me it's because I have a small amount of solar so my batteries are often empty for me i set my DC shutdown to 46v restart 48v and input low pre-alarm 49.4.

Absorption voltage I go slightly higher 55.36 but essentially the same (with BMS balancing enabled at 55.2)

In regards to absorption time I'd play around with it, check the BMS settings make sure cells are balancing in that time frame but 1hr sounds fine to me. You may want to increase the repeated absorption time but play around with these see how your battery manages. Totally fine settings to start with in my opinion. And if cells are balancing with no issues then i'd leave them as is. If they're balancing a lot and often that's when i'd maybe increase the repeat time.

I'm also more conservative with my cut off voltages for each discharge current, I've set mine at 49, 49,48.5 48. However again this is because my batteries can often be empty for a few days so I wanted a decent buffer between shutoff and true empty.

Smart shunt. Charged voltage I personally set to same as absorption, but 55 to 55.2 will be minimal capacity so that's fine. Tail current I've got set higher 4% (but no real reason for it) however my absorption time is longer than yours.

Peukert exponent i use 1.02 and 98% efficiency but 1.01 is 99 is correct for an ideal LiFePO4, again you'll spot if this is off as smart shunt wont be consistent. ie charge to 100% then next full charge you'll maybe get 95% or vice versa.

question