Growatt 3000 dont charge according to settings?

Arne999

New Member
Joined
Sep 26, 2022
Messages
38
I have just setup my growatt 3000 with a 7kWh Prismatic 24V battery. The battery has a Daly BMS (75A charging and 150A discharge)

Yesterday I runned the batteries down (off grid) to 2.9V where the cutof is for the moment (everything looks well balanced). Then I plugged in the grid at time 0h.The following happened:

T=0h: charge current ~20A for maybe 20 minutes then zero A (bettery cells ~~3.0xV)
T= 0.3-2h: No charging....
T=2h-2.3h: 20 min 20A charging
.
.
.
T=8h the battery cells are still at 3.0xV

1664348484991.png

So why are not the charger running continously until the battery reaches max values in the setings?

Some settings:
High voltage cutoff in BMS 3.5V (28V)

Growatt settings
05: Battery type Use2
19: C.V charging voltage 28V
20: Floating 27V
21 Low cutoff 23.2V

11: Max utility charging 30A
12 Setting voltage back to utility . 23V (whatever that means?)
13: Setting voltage point back to battery mode....: 27V (whatever that means?)
14; SNU Solar energy and utility will both charge the battery

I measured the battery voltage at the growatt terminals when charing 20-25A and it was ~24V som there is no issue with wirering. I have 50mm2 wires running from battery checked all connections etc ..
 

Mattb4

Photon Sorcerer
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Jul 15, 2022
Messages
1,423
First thing to understand is when the Growatt is running in inverter mode you do not get any charging from utility.

12. Back to utility voltage is when the battery reaches the voltage low point (23v in your case) it transfers to utility AC Bypass operation.
13. AC bypass mode will not transfer back to the inverter mode until the battery/solar voltage reaches the voltage set point (27v)

I personally do like how low the default transfer to utility voltage is at and I have my Easun inverter unit set at 25v This leaves me at around 18-20% battery capacity but prevents forcing a low voltage cutoff situation or a BMS trip. The Utility to battery voltage I run at 26.6v. That just seems to work better for me on maximizing solar powering loads. Your setup should be what works best for you.

Settings for max voltage and floating voltage you are running are lower than what I run.See if your Manual has a table for lithium battery settings.
 

TomC4306

Solar Obsessive
Joined
Mar 2, 2021
Messages
807
Location
Maryland, USA
Disclaimer: I do not own a Growatt.
I have read more than once here on the forum about USE2 being problematic unless you own a Growatt battery.

Try using USE.
Same settings.
 
Last edited:

Arne999

New Member
Joined
Sep 26, 2022
Messages
38
many thanks! I will try. The manual is not the best source of information
 

Arne999

New Member
Joined
Sep 26, 2022
Messages
38
First thing to understand is when the Growatt is running in inverter mode you do not get any charging from utility.

12. Back to utility voltage is when the battery reaches the voltage low point (23v in your case) it transfers to utility AC Bypass operation.
13. AC bypass mode will not transfer back to the inverter mode until the battery/solar voltage reaches the voltage set point (27v)

I personally do like how low the default transfer to utility voltage is at and I have my Easun inverter unit set at 25v This leaves me at around 18-20% battery capacity but prevents forcing a low voltage cutoff situation or a BMS trip. The Utility to battery voltage I run at 26.6v. That just seems to work better for me on maximizing solar powering loads. Your setup should be what works best for you.

Settings for max voltage and floating voltage you are running are lower than what I run.See if your Manual has a table for lithium battery settings.
After a few minutes thinking this does not make sense. i have short "pulses" of 450W during approximately 15 minutes (so ~~ 0.1kWh charging) and then off for 1hour until next "pulse"


There is no way the battery is going from 23V to 27V during this timpe period and with this low amount of energy transferred to the battery.

It looks more like the Growatt is charging for its self consumption only for because that is what it sums up to.

I do really want the growatt to charge when the utility is available, no matter what. I have variable tariff so during night hours I want to fill up the battery.
 

Mattb4

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Jul 15, 2022
Messages
1,423
Not being there to observe your unit's operation all I can go by is standard operational details for these type of units. When you stated in your first post that you did not know what the "inverter to utility" and "utility to inverter" set point voltages (12 and 13) meant I attempted to explain them. That does not mean that your unit is achieving the voltages.

I am not sure that you understand how the utility charging works. There are modes of operations. that you select. SNU means solar and utility work together (while in AC bypass only) to charge your battery up to the combined amperage level set in another setting. (Note: You can select both the solar max charge rate and the utility max charge rate elsewhere). CSO is charge from solar unless it fails than it charges from utility (if in AC bypass operation). CUB charges battery from utility unless it fails then solar charge starts. OSO Only Solar charging

Unfortunately there is no time program that you can set to charge the battery from utility during favorable utility rates.

From the sound of it you are having a battery charging issue that could be from the BMS detecting a bad cell. Your system attempts to charge and the BMS disconnects it.
 

Arne999

New Member
Joined
Sep 26, 2022
Messages
38
Im very familiar with power electronics and converters but the Growatt is a "black box" with input and outputs where I only can guess what is going on inside :) . It would be nice with a block diagram showing the different converters. I really dont think the issue is the BMS. I have observed the values a lot and the cells are stable and far from any limit. The growatt only sees the total voltage anyway.

For the moment I have set SNU "Solar energy and utility will both charge battery"
You say : "if in AC bypass operation " but what decides if the converter goes into AC bypass operation? (My assumption is that AC bypass means that the grid input is directly connected to output via relay, no converter/semiconductor stuff in between. When AC is bypassed no energy can come from PV or battery to the load, or? Otherwise the power could potentially be fed to the grid.


So... during the night when I have the charging "pulses" PV is not availiable. So what triggers the charging? Its not the low/high voltage settings since im somewhere in the middle.

12 is set to 23
13 is set to 27

01 is set to SbU ()

I cant really find any clear info in the manual when the utility charges the battery. I would like to have the following result (or as close as possible) from the settings:

If only utility is avaliabe:
  • Charge the battery to xV (75% SOC maybe)
  • Bypass to load
  • dont use the battery
If utility & PV is avaliable
  • Prioritise PV to supply the load.
  • Utility provides the potential gap between PV and load demand
  • Charge the battery with PV only.
  • Exception to charge with PV only: If Vbat< xV charge from PV and utility

If utility is unavaliable

  • No brainer, feed the load with PV first, and complement with battery if needed

Just a short description of my goal with the setup:

I have a varable tarif so I plan to have a timer on a utility swith that turns of the utility during expensive hours . SO when the utility is avaliabel (my choise) means that the price is low and I dont want to waste any storage, or losses converting AC/DC/AC. There are also time periods when the cost of electicity is more or less free, especially during nighttime windy days. Since I live in Sweden and the winter is coming the PV contribution will be negliglbe so I really want to charge the battery from the grid.

My backup plan to this is to connect an external charger that I have full control of.... feels a bit unnecessary since the Growatt has a charger already...
 

Mattb4

Photon Sorcerer
Joined
Jul 15, 2022
Messages
1,423
...

For the moment I have set SNU "Solar energy and utility will both charge battery"
You say : "if in AC bypass operation " but what decides if the converter goes into AC bypass operation? (My assumption is that AC bypass means that the grid input is directly connected to output via relay, no converter/semiconductor stuff in between. When AC is bypassed no energy can come from PV or battery to the load, or? Otherwise the power could potentially be fed to the grid.


So... during the night when I have the charging "pulses" PV is not availiable. So what triggers the charging? Its not the low/high voltage settings since im somewhere in the middle.

12 is set to 23
13 is set to 27

01 is set to SbU ()

I cant really find any clear info in the manual when the utility charges the battery. I would like to have the following result (or as close as possible) from the settings:
The inverter goes into AC bypass operation based on modes of operation selected. In your case SBU which means inverter operates from solar/battery as long as voltages meet the Inverter to utility and the utility to inverter voltage set points. Note that Inverter will not transfer if there is no AC in. Also the battery voltage must recover to above the recovery set point voltage. There is no parallel with grid in any case.

The manual on these things can be hard to read and much is left out. Utility can only charge the battery when it is not inverting since it relies on the inverter working backwards to change AC to DC instead of DC to AC.

Perhaps your unit is malfunctioning but it just seems from your symptoms that it is more likely a battery issue. If you can somehow try a different battery you would know for sure.
 
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