Growatt Standby & power save mode question

[wtrey613]

All,
We have an off grid cabin with an Growatt ES 5000 and 2x 5kw server rack batteries. (EG4). We leave this cabin intermittently and don't check our growatt. What settings for our growatt should be enabled so that when the sun hits the panels, the growatt turns on, charges the batteries, and then turns off when the sun goes down so the growatt is not being used at night. We are not providing loads to our cabin at this time.

Right now, it was our understanding that we should have it on Standby and power save mode Enabled. but when we showed up to our cabin one day, Full sun in the afternoon, the growatt was blank and did not trigger on because of the sun.

Let me know what setting i need to change it to. We are also set to SBU.

 

[Rednecktek]

You should be able to just set everything up for regular use and turn off the inverter via the toggle switch on the bottom. It should still charge the panels once the sun comes up. If the battery is full it may not charge but it should still keep everything topped up.

 

[wtrey613]

You should be able to just set everything up for regular use and turn off the inverter via the toggle switch on the bottom. It should still charge the panels once the sun comes up. If the battery is full it may not charge but it should still keep everything topped up.

Okay then i think there is an issue with our growatt... we have been doing that but when we arrive back to our camp after having turned the growatt in standby mode; there is full sun but the growatt is dark and not charging the batteries. Must be something wrong with our growatt.

 

[octal_ip]

Is it possible that the battery voltage hasn't dropped sufficiently to require charging? Growatt AIOs have a battery voltage threshold that needs to be passed before the charging algorithm kicks back in again. With the unit in standby mode, it could take a very long time before the batteries drain enough to pass this threshold.

 

[wtrey613]

Is it possible that the battery voltage hasn't dropped sufficiently to require charging? Growatt AIOs have a battery voltage threshold that needs to be passed before the charging algorithm kicks back in again. With the unit in standby mode, it could take a very long time before the batteries drain enough to pass this threshold.

Could you explain this in more detail for me to understand? This might be a possibility when we show up to camp and we turn back on the growatt, our batteries are around 70%~ so maybe when they drop below say 50% the growatt on standby kicks back on during the day?
I am going through the settings manual and there doesnt seem to be a setting that allows me to change that.

 

[octal_ip]

Could you explain this in more detail for me to understand? This might be a possibility when we show up to camp and we turn back on the growatt, our batteries are around 70%~ so maybe when they drop below say 50% the growatt on standby kicks back on during the day?
I am going through the settings manual and there doesnt seem to be a setting that allows me to change that.

Here you go: https://diysolarforum.com/threads/growatt-odd-behavior.22696/post-666236

 

[Rednecktek]

Could you explain this in more detail for me to understand? This might be a possibility when we show up to camp and we turn back on the growatt, our batteries are around 70%~ so maybe when they drop below say 50% the growatt on standby kicks back on during the day?
I am going through the settings manual and there doesnt seem to be a setting that allows me to change that.

Yeah, that's odd. It should have kicked on long before it gets to 70% and started charging...

 

[octal_ip]

It all depends on the voltages. Assuming there's no comms between the BMS and Growatt, the Growatt has no idea what the battery state of charge is. It can only measure voltage, which is somewhat constant for LiFePO4 outside the extremes of the charge/discharge knees (above 90%, below 20%).

My guess is that this problem might be addressed by raising the C.V. charging voltage and setting the float charging voltage only slightly lower (within 0.5v). This makes sure the Growatt can measure the required voltage drop for the charger to activate again as the battery state of charge reduces.

 

[wtrey613]

It all depends on the voltages. Assuming there's no comms between the BMS and Growatt, the Growatt has no idea what the battery state of charge is. It can only measure voltage, which is somewhat constant for LiFePO4 outside the extremes of the charge/discharge knees (above 90%, below 20%).

My guess is that this problem might be addressed by raising the C.V. charging voltage and setting the float charging voltage only slightly lower (within 0.5v). This makes sure the Growatt can measure the required voltage drop for the charger to activate again as the battery state of charge reduces.

we have a com cable that goes to the growatt, so there is a Comms between the BMS and growatt. but i see what your saying it only measures voltage at the end of the day.

So you are suggesting, in setting 19, to raise it from the default 56.4 v to say 57 or 58v?
and with setting 20, default to 54.0v, and lowing it to say 53.5V? or 53v?

Again our main issue, is that while we are away, we had the growatt on Standby and Power save enabled. we came back to our cabin with full sun and the batteries were at 70%, and the growatt screen was dark with Full sun our panels.
This leads me to believe there is something wrong with the Growatt.

 

[octal_ip]

So you are suggesting, in setting 19, to raise it from the default 56.4 v to say 57 or 58v?
and with setting 20, default to 54.0v, and lowing it to say 53.5V? or 53v?

No, do the opposite. Leave setting 19 as-is, but change 20 to 56v. This should make sure that the battery passes the low voltage threshold sooner to allow charging again.
I'd recommend reading the thread I linked to to build an understanding of the strangeness of the Growatt charging algorithm.

 

[kirkdis]

we have a com cable that goes to the growatt, so there is a Comms between the BMS and growatt. but i see what your saying it only measures voltage at the end of the day.

So you are suggesting, in setting 19, to raise it from the default 56.4 v to say 57 or 58v?
and with setting 20, default to 54.0v, and lowing it to say 53.5V? or 53v?

if you have a comms cable connected and protocolls are set properly all the voltage settings are not accessible anymore or don´t do anything to control the charging. As soon the BMS has a working communication the BMS controlls the charging procedure...