Hi all.

I would really appreciate some Sunsynk user Wisdom from those that have the T-Shirt.

In a nut shell.

Grid tied (with all loads Non-Essential or still connected to Grid) , with PV and Lithium batteries ......batteries without a communicating BMS so battery set up as AGM V and using voltage setpoints.

What I was expecting is that........in the early morning hours when the battery gets depleted and Battery voltage reaches "Shutdown" voltage which is et to 49V, the Inverter would taper off on battery power supplying the load and progressively use more grid power to take over load. (From a battery power point of view, similar to what you see at top of charge where charge power just gets progressively less as you reach target charge voltage).

I though it was doing that........... but it has become apparent in the last two days where we have used more of the battery capacity than usual, that the Inverter just keeps on providing power from the batteries and dropping V to below any of voltage setpoints even though grid is present.

IIRC the setpoints are as follows:

ShutDown 49V

Restart 50V

Low Batt 48.8 (I set it to below shut down because I am expecting the battery to be drained to the shutdown setpoint daily .......battery continued to discharge below this threshold also so didnt seem to have any affect related to what I am experiencing?)

Am I missing something obvious?

And also, what is the point of the setpoint "Batt Empty V"? A description "this is the voltage at which the battery will be completely flat" , but I dont see any actions associated with it....and it is likely way below any of the other setpoints so does it have a purpose?

Thanks Guys

Edited March 4, 20251 yr by MYBRIDH

6 hours ago, MYBRIDH said:

Hi all.

I would really appreciate some Sunsynk user Wisdom from those that have the T-Shirt.

In a nut shell.

Grid tied (with all loads Non-Essential or still connected to Grid) , with PV and Lithium batteries ......batteries without a communicating BMS so battery set up as AGM V and using voltage setpoints.

What I was expecting is that........in the early morning hours when the battery gets depleted and Battery voltage reaches "Shutdown" voltage which is et to 49V, the Inverter would taper off on battery power supplying the load and progressively use more grid power to take over load. (From a battery power point of view, similar to what you see at top of charge where charge power just gets progressively less as you reach target charge voltage).

I though it was doing that........... but it has become apparent in the last two days where we have used more of the battery capacity than usual, that the Inverter just keeps on providing power from the batteries and dropping V to below any of voltage setpoints even though grid is present.

IIRC the setpoints are as follows:

ShutDown 49V

Restart 50V

Low Batt 48.8 (I set it to below shut down because I am expecting the battery to be drained to the shutdown setpoint daily .......battery continued to discharge below this threshold also so didnt seem to have any affect related to what I am experiencing?)

Am I missing something obvious?

And also, what is the point of the setpoint "Batt Empty V"? A description "this is the voltage at which the battery will be completely flat" , but I dont see any actions associated with it....and it is likely way below any of the other setpoints so does it have a purpose?

Thanks Guys

Mine works exactly as intended (also using AGM V setting) and will use Grid from the relevant set point that has been set in the the Time of Use setting.

I would however not recommend using the Low battery setting and the Shutdown setting to achieve what you want, rather use the Time of Use setting to achieve what you want.

The Shutdown voltage, once reached, will cause the inverter to shut off completely (all power to the house will be lost) and it will only restart again once the restart voltage is reached. I can only imagine that you have confused the inveter by setting the low battery voltage point lower than the shutdown voltage (I just checked on mine and it does not allow me to enter such a setting) which is why it did not shut down (fortunate for you) as intended.

49 minutes ago, I84RiS said:

Mine works exactly as intended (also using AGM V setting) and will use Grid from the relevant set point that has been set in the the Time of Use setting.

I would however not recommend using the Low battery setting and the Shutdown setting to achieve what you want, rather use the Time of Use setting to achieve what you want.

The Shutdown voltage, once reached, will cause the inverter to shut off completely (all power to the house will be lost) and it will only restart again once the restart voltage is reached. I can only imagine that you have confused the inveter by setting the low battery voltage point lower than the shutdown voltage (I just checked on mine and it does not allow me to enter such a setting) which is why it did not shut down (fortunate for you) as intended.

Thank you very much.

I will check out those settings and time of use options and get back to you.

On 2025/03/04 at 8:37 PM, I84RiS said:

Mine works exactly as intended (also using AGM V setting) and will use Grid from the relevant set point that has been set in the the Time of Use setting.

I would however not recommend using the Low battery setting and the Shutdown setting to achieve what you want, rather use the Time of Use setting to achieve what you want.

The Shutdown voltage, once reached, will cause the inverter to shut off completely (all power to the house will be lost) and it will only restart again once the restart voltage is reached. I can only imagine that you have confused the inveter by setting the low battery voltage point lower than the shutdown voltage (I just checked on mine and it does not allow me to enter such a setting) which is why it did not shut down (fortunate for you) as intended.

Hey I84RiS

Much appreciate that guidance, thank you.

Some feedback.

I think the Shutdown Voltage didnt affect me that way because all my loads are connected to grid (as Non-Essential), if the inverter were to stop supplying power from battery it would just be coming straight from the grid.

When we had this last bout of load shedding I temporarily moved the loads to the Inverter Load (Essentials) terminals and it behaved as you said, no AC output when battery is depleted and AC only available again once PV has charged the battery back up to Startup Voltage.

Wrt the Low Battery Voltage setpoint............and also some other setpoints I noticed (Time of use Voltage setpoint IIRC)..........is that when changing it on the inverter interface, the range is limited depending on other setpoints , when you change that same setpoint using the Web or Android (Sunsynk Connect) app it makes the change and it seems to stick without any protest.

I tried out of interest, and under different use case scenario or using other functionality it might behave differently, but it seems that in my case setting the Low Batt V setpoint to below Shutdown V (using the android app) does not present any problem. On the Inverter I couldn't set the Time of Use Voltages below the Low Battery Voltage setpoint , which I could on the Android interface and it still seemed to work as far as allowing the battery to discharge or be charged accordingly...........Once I actually got it working.

To summarize the issue. As you pointed out I needed to focus on the Time Of Use settings. Coincidentally , I had the voltages set up there correctly, but I did not have the Grid boxes checked.......to my mind the intention was not to charge...........only to prevent discharge beyond that voltage so it didnt make sense to me that they needed to be "Charged".

Once I did that.....I still couldnt get it to work ......took me a while and a couple of Youtube videos to realize that in addition to the Time of Use settings I needed to check the Grid Charge box under Battery Settings as well.

So, finally working. In hind sight some thing become more obvious that they seemed initially can only imagine how many people are rolling their eyes thinking......RTFM.

Once again, thank you for taking the time to steer me in the right direction.

Much appreciated.

I am also using Volts and low batt and shutdown around 47.5V.

I have also had a few shut downs when my timer setting to start using grid was too close to these settings. That caused a single surge load like a fridge to drop to these levels. Since using my timer activated from 23h30 up to 07h00 at a 50V level it works fantastic to feed in grid at a low level just to keep at this 50V level. Now I find it only uses the always from grid 50W most days and only a 30min grid charge below 100W while my total load is around 380W of which the self use power is about 68-80W. This is used at 05h30-06h30 for the mentioned 30min when PV starts kicking in. This grid use of 100W only takes place if we had weak sun and battery did not charge to 100%. The SOC is then around 20% +.

Edited March 10, 20251 yr by Scorp007
Added pic

On 2025/03/10 at 12:04 AM, Scorp007 said:

I am also using Volts and low batt and shutdown around 47.5V.

I have also had a few shut downs when my timer setting to start using grid was too close to these settings. That caused a single surge load like a fridge to drop to these levels. Since using my timer activated from 23h30 up to 07h00 at a 50V level it works fantastic to feed in grid at a low level just to keep at this 50V level. Now I find it only uses the always from grid 50W most days and only a 30min grid charge below 100W while my total load is around 380W of which the self use power is about 68-80W. This is used at 05h30-06h30 for the mentioned 30min when PV starts kicking in. This grid use of 100W only takes place if we had weak sun and battery did not charge to 100%. The SOC is then around 20% +.

Appreciate you sharing that insight that thank you Scorp007.

Been working great since the changes, My settings are quite close together, no issue yet and I will keep this in mind if I start having any issues.