DEYE SUN-12K no decharge below 9%

[Janmn]

When the battery is decharged to 9% the inverter immediately charges it to 13% and then this cycle is repeated infinitely. This happens independently of the settings in the battery pack and the settings in the inverter. I have set the low battery to 5% and the shutdown to 3%. In addition, in "time of use" the low battery is set to 5%.
Is it some kind of safety function and can it be disabled?

 

[DIYrich]

Turn off charge from grid.

 

[shadowmaker]

Had similar thing happening with my Deye12K, but mine just stopped discharging @8% while batt cell voltages were around 3,18V. Found out that it was batt BMS which had SOC protection enabled, so just disabled it and now I can get down to 5% (3,0V). If I go under 5% it will start charging batts even grid charge disabled. I bet it's batt BMS again, but I don't mind as I don't want my cell voltages to drop below 3,0V because there's not much capacity left anyhow at that point.

 

[Janmn]

It recharges the battery even if grid charge is disabled!
It is not the BMS that that is "asking" to be charged. I have checked all settings including soc warnings. in addition I have monitored the Bms while it happens and no criteria is fulfilled that triggers an alarm or warning.

 

[DIYrich]

If grid charge is disabled on the inverter, then it shouldn't charge from the grid, regardless of what the bms asks for.

 

[Janmn]

I agree, but it does charge from the grid!

 

[houseofancients]

When the battery is decharged to 9% the inverter immediately charges it to 13% and then this cycle is repeated infinitely. This happens independently of the settings in the battery pack and the settings in the inverter. I have set the low battery to 5% and the shutdown to 3%. In addition, in "time of use" the low battery is set to 5%.
Is it some kind of safety function and can it be disabled?

This is a setting, and is a battery safety setting.
One can chance it, but would HIGHLY recommend not doing so
Charging is depending on source availability

 

[Janmn]

I understand the risk, but
- I think its safe to decharge to 5% SOC.
- I find that it's very inappropriate that the inverter goes into this endless loop of charging and decharging between 9-13%.

 

[houseofancients]

I understand the risk, but
- I think its safe to decharge to 5% SOC.
- I find that it's very inappropriate that the inverter goes into this endless loop of charging and decharging between 9-13%.

It is trying to save your batteries from a PEBKAC

 

[houseofancients]

It also means you haven't setup Time Of use correctly

 

[DIYrich]

9% soc is where it may be disconnecting the battery under load. When load is disconnected, the battery settles to 13% soc resting. The inverter sees the higher soc and draws again, quickly dropping the soc back to 9%. Rinse and repeat.

There is a reconnect battery setting. Set it to 35% soc. When the battery disconnects at 9% soc, it won't try to use the battery again until it hits 35% soc.

 

[Janmn]

The Time of use is set to 5% and NO grid charge.

It is not a matter of the battery is settling. When it hits 9%, within 10s the current drops to 0 and ramps up to charging at 100A (current setting for max charging) and after approximately 11 min. 13% is reached and decharging starts again.

 

[DIYrich]

It is not a matter of the battery is settling. When it hits 9%, within 10s the current drops to 0 and ramps up to charging at 100A (current setting for max charging) and after approximately 11 min.

If you turned off grid charging, it shouldn't EVER charge from grid.

If the deye is like the sol-ark, on the battery setup screen, charge tab, make sure Grid Charge is unchecked.

On the time of use settings, make sure all the boxes under Charge are unchecked.

 

[Janmn]

honestly, I did. but I has no effect after the inverter has entered this "safety mode"

 

[DIYrich]

Maybe you should post pictures of all your screens.

 

[Janmn]

I will try. Meanwhile my question is:
Are anyone able to use energy stored on a lithium battery between 5-10% SOC with a Deye hybrid inverter?

 

[shadowmaker]

I will try. Meanwhile my question is:
Are anyone able to use energy stored on a lithium battery between 5-10% SOC with a Deye hybrid inverter?

Yes, but only after disabling "SOC protection" not "SOC warning" from battery BMS. And mine will charge from the grid regardless Deye settings. I have closed loop connection, so it's the batt BMS who is in charge. Normally it won't charge from grid if grid charge is disabled from Deye and everything works as planned, but when batt BMS sees too low cell voltages, it forces Deye to charge from grid to protect battery. Not problem for me as I don't want my batts go that low anyway. I think this is BMS model related "problem". Not all BMSs do this.

What are your cell voltages/pack voltage @9% SOC?

 

[shadowmaker]

I have monitored the Bms while it happens and no criteria is fulfilled that triggers an alarm or warning.

I did this too. There was nothing to trigger charging no matter how hard I tried to find it. Then went through "protection list" and disabled "SOC protection" for the heck of it and got it working.

 

[houseofancients]

I did this too. There was nothing to trigger charging no matter how hard I tried to find it. Then went through "protection list" and disabled "SOC protection" for the heck of it and got it working.

And you didn't get the idea SOC protection was there for a reason ?
In general Don't get why people feel the need to go again cell manufactorer, inverter manufactorer and battery manufactorer.
If you need to go that low, maybe it is time to add batteries

I understand one may want to do so for some testing once or twice..
But thats it

 

[Janmn]

Yes, but only after disabling "SOC protection" not "SOC warning" from battery BMS. And mine will charge from the grid regardless Deye settings. I have closed loop connection, so it's the batt BMS who is in charge. Normally it won't charge from grid if grid charge is disabled from Deye and everything works as planned, but when batt BMS sees too low cell voltages, it forces Deye to charge from grid to protect battery. Not problem for me as I don't want my batts go that low anyway. I think this is BMS model related "problem". Not all BMSs do this.

What are your cell voltages/pack voltage @9% SOC?

I tried with no effect. see attached picture taken right before it starts to charge. This time i tried Lithium mode 12 to see if communication protocol influences the behavior.

 

[shadowmaker]

And you didn't get the idea SOC protection was there for a reason ?
In general Don't get why people feel the need to go again cell manufactorer, inverter manufactorer and battery manufactorer.
If you need to go that low, maybe it is time to add batteries

I understand one may want to do so for some testing once or twice..
But thats it

Yes, but it's Chinese engineering... (actually they have been very helpful every time I have asked help)

With SOC protection enabled my batts stopped discharging around 3,17-3,19V cell voltages. From all the reading I have done I concluded going down to 3,0V and with max 0,16C discharge it should still be safe with LFP and shouldn't affect cycle life much.

EDIT. And yes I certainly could do with more batteries (2x10kWh more ordered), but for summer 100-150kWh seems to be enough. For winter I'd need 600kWh to get through 3 days and we can have weeks without any decent sun. I'm grid tied like you already know, so moneywise 600kWh or more is not my best option.

 

[Janmn]

Yes, but only after disabling "SOC protection" not "SOC warning" from battery BMS. And mine will charge from the grid regardless Deye settings. I have closed loop connection, so it's the batt BMS who is in charge. Normally it won't charge from grid if grid charge is disabled from Deye and everything works as planned, but when batt BMS sees too low cell voltages, it forces Deye to charge from grid to protect battery. Not problem for me as I don't want my batts go that low anyway. I think this is BMS model related "problem". Not all BMSs do this.

What are your cell voltages/pack voltage @9% SOC?

I did this too. There was nothing to trigger charging no matter how hard I tried to find it. Then went through "protection list" and disabled "SOC protection" for the heck of it and got it working.

 

[Janmn]

All grid charging disabled

 

[Janmn]

Yes, but it's Chinese engineering... (actually they have been very helpful every time I have asked help)

With SOC protection enabled my batts stopped discharging around 3,17-3,19V cell voltages. From all the reading I have done I concluded going down to 3,0V and with max 0,16C discharge it should still be safe with LFP and shouldn't affect cycle life much.

It's absolutely true that it's safe to go down to 3,0V. it's also true, and very well documented, that you can't rely on the standard settings of inverters or battery packs. Of course some people prefer to live in blissful ignorance.

 

[shadowmaker]

I tried with no effect. see attached picture taken right before it starts to charge. This time i tried Lithium mode 12 to see if communication protocol influences the behavior.

I see your problem there in the picture. A very different looking BMS tool compared to mine (got it from the manufacturer, but don't know even know who's the manufacturer of my BMSs as my batts are prebuilts and very cheap ones, so they probably have cheap/shitty BMSs too).

Maybe your problem has nothing to do with my solution. It's just that your batts are behaving just like mine did before.

Of course some people prefer to live in blissful ignorance.

If you refer to @houseofancients, please don't. You'll find out he is one of the wise ones here and knows his Deye/Sunsynk stuff. Very grateful to him for helping me out many times.