Where is the "low voltage disconnect" setting in the Deye/Sunsync inverters?

[kolek]

I want the inverter to stop discharging the battery based on voltage.
I do NOT have communications between the BMS and the inverter.
Sounds stupid but I cannot find where to set that in my Deye 8K.

 

[sunshine_eggo]

Batt Set3 screen?

 

[kolek]

This is an image captured from another website, but I am assuming it is this screen which I have never actually found in the settings.

Shutdown = low battery cutoff voltage?
Restart = turn on the battery again after it reaches this voltage?

And I assume to get to this page you have to first choose "voltage" as the control parameter for the battery.
I'll try it tomorow morning, my inverter is shut off now because battery is low and no grid connection to charge.

 

[kolek]

I assume more conservative settings for shutdown would be somewhere between 3.1V and 3.3V per cell? Any thoughts on this?

 

[sunshine_eggo]

3.0V is around 10%. That's where I'd start. 3.1 would probably work, but 3.3 would make your system unusable.

 

[kolek]

3.0V is around 10%. That's where I'd start. 3.1 would probably work, but 3.3 would make your system unusable.

That's good to know. What made me think possibly as high as 3.3V was this comment on reddit discussing 48V battery discharge levels (for a different application):

"You really never want to go below 3.0 V/cell under load. Personally I only discharge to 3.3 V/cell or higher. For a 14S 52V battery that's 42V and 46.2V, respectively.

The shallower the discharges (as opposed to deep discharge) you are doing on your battery, the longer it will last. It's a quasi-subjective balancing act between length of useful life and convenience. You can find the datasheet for the specific cells and it will tell you what the minimum voltage is, but the above still stands."

 

[sunshine_eggo]

That's good to know. What made me think possibly as high as 3.3V was this comment on reddit discussing 48V battery discharge levels (for a different application):

"You really never want to go below 3.0 V/cell under load. Personally I only discharge to 3.3 V/cell or higher. For a 14S 52V battery that's 42V and 46.2V, respectively.

The shallower the discharges (as opposed to deep discharge) you are doing on your battery, the longer it will last. It's a quasi-subjective balancing act between length of useful life and convenience. You can find the datasheet for the specific cells and it will tell you what the minimum voltage is, but the above still stands."

Be careful what you read on the internet. That information does not pertain to YOUR batteries, LFP. The clue is 14S. That's 3.6-3.7V Lithium-ion (NCA, NMC, LMO, etc.) chemistry which has a typical operating range of 3.0 to 4.2V/cell, hence the lower cell count than your typical 16S 3.2V LFP "48V" battery. It also has a definitive voltage to SoC relationship. I have an NMC battery, and my lower end target is 3.5V. I charge to 3.92V. This is about 20-75% SoC for my battery, and it doesn't apply to yours in any way.

 

[kolek]

Be careful what you read on the internet. That information does not pertain to YOUR batteries, LFP. The clue is 14S. That's 3.6-3.7V Lithium-ion (NCA, NMC, LMO, etc.) chemistry which has a typical operating range of 3.0 to 4.2V/cell, hence the lower cell count than your typical 16S 3.2V LFP "48V" battery. It also has a definitive voltage to SoC relationship. I have an NMC battery, and my lower end target is 3.5V. I charge to 3.92V. This is about 20-75% SoC for my battery, and it doesn't apply to yours in any way.

Ok, thanks for the explanation!

 

[kolek]

Which setting is the high voltage cutoff that tells the inverter to stop charging?
Absorbtion V?

 

[sunshine_eggo]

Which setting is the high voltage cutoff that tells the inverter to stop charging?
Absorbtion V?

Yes. It doesn't just stop at that voltage. It should hold the voltage while the current tapers off for full charging.