SMA Sunny Island 6048 and Lifepo4 batteries (open loop)

[Hedges]

It has to charge to a high enough voltage to re-synchronize.
I don't think 48V nominal, 24 cell VRLA settings allow voltages that match LiFePO4 top and bottom voltages.
I think some other nominal VRLA settings will accomplish that. Should be able to get max voltage suitably above the knee for balancing, and min voltage suitably below the knee to use most capacity without completely draining.

That's just number of cells and cell voltage settings. Whether SI considers Peukert and allows lower voltage under heavy load, I don't know. If not, apparent SoC would snap back when lead-acid is not under load. Lithium has lower series resistance.

Would like to have a protocol converter, so other brand BMS are made to emulate REC which SI understands.

There are going to be so many different lithium brands and chemistries, and a BMS is required anyway to access individual cells, so it makes sense for BMS to communicate with SMA. If SI only looked at pack voltage it would not know if there was a runner, and charge current/voltage needed to back off and allow balancing.

 

[Ai4px]

Maybe there's some combination of settings that will let the system run forever, but I've tried many things and no matter the SI eventually gets off sync from the actual SOC. It's impossible to use the lower part of my battery safely without a potential shutdown or my batteries drained to 0.

Madsci1016 could get the Victron smart shunt to work fully. I've tried to reach out to him but no response. If someone is able to do the coding and get it working I would be glad to pitch in or buy the code. I may build a new bank and use a SI supported BMS. One battery should mostly reflect the over all SOC, at least better than spoofing the SI. Why SMA won't support lithium directly, stinks.

Is there a list of BMS's that work with SI?

 

[Hedges]

We know that REC does, or at least REC makes a model that does. for Sunny Island 6048US.
Don't know if European Sunny Island works with the same, or the high-voltage Sunny Boy Storage.

see "REC SI BMS"

BATTERY MANAGEMENT SYSTEM – REC BMS

www.rec-bms.com

"compatible with SMA Sunny Island H/M series, Studer Innotec and Victron inverters"

 

[mapsurfer]

There are alot of cheap batteries that have built-in bms but I had email sma and after a few weeks they referred me to the list of compatible batteries which are mostly hard to get, or cost prohibitive. said the built-in bms Chinese batteries were incompatible with the SI. The lifepo4 batteries with canbus can be expensive, but can anyone recommend batteries?

 

[billt1827]

We know that REC does, or at least REC makes a model that does. for Sunny Island 6048US.
Don't know if European Sunny Island works with the same, or the high-voltage Sunny Boy Storage.

see "REC SI BMS"

BATTERY MANAGEMENT SYSTEM – REC BMS

www.rec-bms.com

"compatible with SMA Sunny Island H/M series, Studer Innotec and Victron inverters"

The REC SI BMS only has monitoring for 16 cells so is intended for a nominal 48V battery. The SI 8.0H that I have works with a REC BMS and 48V battery, in my case self assembled from individual cells (400Ah Winstons).

I'm experimenting with increasing the storage capacity by adding cheaper cells in a parallel battery with a separate BMS which doesn't communicate with the SI. The idea is that the REC BMS talks to the SI to control the charge rate and the paralleled batteries should track with their BMSs just used for cell protection. It seems to be working with one extra battery, we'll see what happens with the other 2 that are lined up.

 

[Hedges]

REC offers products which can be connected supporting up to 128s.
I don't know whether that capability, and Sunny Island support, are mutually exclusive.
I don't know how 16s4p might be supported, if multiple BMS systems can talk to each other. And then there is 4p16s, which would use one BMS.

What I'm daydreaming about is a high voltage string, AC coupled and responding to frequency-watts.
Sunny Boy Storage connects with up to three nominally 400V batteries (large voltage range, but current limit would reduce watts available at lower voltages.)
It is meant for grid support and shaving. Don't know if it would play nice with Sunny Island off-grid.

 

[billt1827]

I know nothing about Sunny Boy storage with high voltage batteries.

The official REC system for parallel batteries is to use a REC BMS for each battery. The BMSs can communicate on the RS485 bus in a master/slave configuration. DIP switches are used to set the BMS address with 15 addresses available which would give a theoretical limit of 240 cells.

 

[toms]

The REC SI BMS only has monitoring for 16 cells so is intended for a nominal 48V battery. The SI 8.0H that I have works with a REC BMS and 48V battery, in my case self assembled from individual cells (400Ah Winstons).

I'm experimenting with increasing the storage capacity by adding cheaper cells in a parallel battery with a separate BMS which doesn't communicate with the SI. The idea is that the REC BMS talks to the SI to control the charge rate and the paralleled batteries should track with their BMSs just used for cell protection. It seems to be working with one extra battery, we'll see what happens with the other 2 that are lined up.

I’m keen on to follow your progress on that one. The only issue I can see is that the balancing current will be controlled only by the primary pack, and if it is too high for the parallel pack the parallel pack’s BMS will have to disconnect itself which may cause issues.

With the REC, it can protect itself by commanding no charge current (eg if the balance resistors are getting hot). The parallel packs will have not have that function.

I use a cheaper inverter, and set up a completely separate system, then feed the AC output into the grid feed of the Sunny Island.

There is a transfer switch on this circuit so that the secondary system can power the house if required.

 

[Ai4px]

Maybe there's some combination of settings that will let the system run forever, but I've tried many things and no matter the SI eventually gets off sync from the actual SOC. It's impossible to use the lower part of my battery safely without a potential shutdown or my batteries drained to 0.

Madsci1016 could get the Victron smart shunt to work fully. I've tried to reach out to him but no response. If someone is able to do the coding and get it working I would be glad to pitch in or buy the code. I may build a new bank and use a SI supported BMS. One battery should mostly reflect the over all SOC, at least better than spoofing the SI. Why SMA won't support lithium directly, stinks.

I don't mind batteries drained to zero (on paper).... it's what I have a BMS for... But an early shutdown with 50% in the battery is going to upset the "management" around my house.
It would be really slick to have a some code on an arduino that talked to victron smart shunt and translated it to the CANBUS data that SI needs. Or if I could just tell SI it had 100% soc forever.... and deal with the real SOC externally with an alarm in my kitchen or something.

 

[Ai4px]

Does anyone know about this device? Can we use it as a starting point? I mean I can do mod bus. Arduino anyone????? Bueller? Bueller? https://www.midnitesolar.com/pdfs/10-269-1_Rev_A_Communication_Adapter_Manual_preliminary.pdf

 

[Hedges]

"MidNite Solar’s Communication Adapter is a software protocol converter for creating a communications link between SMA’s Sunny Island inverter and MidNite Solar’s Classic charge controllers, which allows these products to work together as a system. Translating Midnite Solar’s communication protocol into SMA format, and vice-versa, allows up to four Classics to communicate with a single Sunny Island inverter. As a system the Classics are able to report their energy production data, (i.e. - voltage, current and power), to the Sunny Island and from there on to the Sunny WebBox, in a similar manner as SMA’s charge controllers report their power production. Going the other way the Sunny Island inverter acts as the system controller, telling the Classics the appropriate voltage set point for the battery state of charge at the time."

That lets Classic emulate MSTE SIC-40, which I have interfaced to SI.
For me that was just plug-and-play.
Some others have done that with the Midnight equipment (as you noticed on another thread.)

I haven't tried to talk to SMA equipment with software, but I think some people here have. I might want to use SpeedWire (Ethernet) for export-limit of GT PV inverters.