Growatt SPF 3000TL LVM 48V Questions

[Dank Farrik]

I’m thinking about building a home power station with 2x 48V rack batteries (EG4 or SOK). Questions for the Growatt experts here regarding the Growatt SPF 3000TL LVM 48V:

1. For Setting 5 (Battery Type), if it’s set to “Li” (battery with Growatt BMS communication), Setting 2 (Max utility + solar charge current) says this:

“(If Li is selected in Program 5, this program can’t be set up)”

Why is this? What if I want to set a max current limit for solar charging?

2. If Setting 5 set to “USE” (User 1) or “US2” (User 2), does the Growatt display still show battery SOC %, or just the battery voltage?

3. In Signature Solar’s product video for the Growatt, they mentioned that you should keep the power switch in the OFF position, connect your batteries, then turn the power switch ON, otherwise the huge inrush current may damage the inverter. This implies that the Growatt has some kind of precharge circuit. Can anyone confirm?

Thanks in advance!

 

[FilterGuy]

In Signature Solar’s product video for the Growatt, they mentioned that you should keep the power switch in the OFF position, connect your batteries, then turn the power switch ON, otherwise the huge inrush current may damage the inverter. This implies that the Growatt has some kind of precharge circuit. Can anyone confirm?

I can confirm that the surge will still happen when the inverter is turned off. The input capacitors are directly on the Battery inputs and will cause the surge regardless if the inverter is on or off. Could you provide a link to the video?

 

[Dank Farrik]

Could you provide a link to the video?

Start at 6:35

 

[FilterGuy]

So... It is true that the inverter should be off when hooking up the battery. However, turning the switch off does not stop the surge of charging the input capacitors. On all inverters I am aware of the on-off functionality is *after* the input capacitors...and I am very confident the Growatt is not different.

I always put an inverter disconnect before the inverter and because of the inrush, I always build in a pre-charge circuit.

Inverter Disconnect Switch with Precharge

To get the paper, click on the orange button at the top of this page. This circuit is designed as a disconnect switch that allows the user to pre-charge the inverter capacitors before turning the switch completely on. 26 June 2020 update: At...

diysolarforum.com

1. For Setting 5 (Battery Type), if it’s set to “Li” (battery with Growatt BMS communication), Setting 2 (Max utility + solar charge current) says this:

“(If Li is selected in Program 5, this program can’t be set up)”

Why is this? What if I want to set a max current limit for solar charging?

The Li setting is for a Growatt battery that communicates directly with the inverter. (As far as I know, Growatt has never actually released the battery that does this but I believe there are 3rd party batteries that will..... maybe it is EG4..??). You should use the custom setting. It will do everything you need/want

 

[Dank Farrik]

So... It is true that the inverter should be off when hooking up the battery. However, turning the switch off does not stop the surge of charging the input capacitors. On all inverters I am aware of the on-off functionality is *after* the input capacitors...and I am very confident the Growatt is not different.

I always put an inverter disconnect before the inverter and because of the inrush, I always build in a pre-charge circuit.

Inverter Disconnect Switch with Precharge

To get the paper, click on the orange button at the top of this page. This circuit is designed as a disconnect switch that allows the user to pre-charge the inverter capacitors before turning the switch completely on. 26 June 2020 update: At...

diysolarforum.com

The Li setting is for a Growatt battery that communicates directly with the inverter. (As far as I know, Growatt has never actually released the battery that does this but I believe there are 3rd party batteries that will..... maybe it is EG4..??). You should use the custom setting. It will do everything you need/want

My understanding is that bother the EG4 and SOK rack batteries have pre-charge circuits built in. So I was just curious if the Growatt also has this. It would make turning things on slightly easier (you have to hold the RST buttons for a few seconds on the batteries from their off state to activate the pre-charge routine).

The EG4 and SOK rack batteries both advertise as being able to communicate directly with a Growatt inverters, that’s why I asked about the “Li” setting. If I use the custom settings (I think “US2” or User 2 setting is made specifically for LFP batteries), will the Growatt still display the SOC as a %?

 

[FilterGuy]

he EG4 and SOK rack batteries both advertise as being able to communicate directly with a Growatt inverters, that’s why I asked about the “Li” setting.

As I recall, @Will Prowse showed this in one of his reviews of one of the batteries in the past month or two. My paraphrase of his comment on it was "Nice but not for me" (Please find the video and get his view directly....I could be remembering wrong)

One thing that I have wondered about the coms connection is whether there are still two levels of protection. With the BMS completely separate, you can set the BMS cut-off points slightly higher/lower than what you set the loads and chargers cut-off to. This way if the load or charger fails, the BMS can still catch it before any damage to the cells. With it all tied together through the com port, does it just count on the battery settings? Does it regress down to a single level of protection? Is that why some of the inverter settings are inaccessible in this mode?

will the Growatt still display the SOC as a %?

I can't say for sure, but I can't see any reason why it would not.

 

[Dank Farrik]

As I recall, @Will Prowse showed this in one of his reviews of one of the batteries in the past month or two. My paraphrase of his comment on it was "Nice but not for me" (Please find the video and get his view directly....I could be remembering wrong)

You wouldn't happen to remember which video, would you? I'm fairly sure I've watched all of @Will Prowse's video from the last couple of months and don't recall seeing this part.

One thing that I have wondered about the coms connection is whether there are still two levels of protection. With the BMS completely separate, you can set the BMS cut-off points slightly higher/lower than what you set the loads and chargers cut-off to. This way if the load or charger fails, the BMS can still catch it before any damage to the cells. With it all tied together through the com port, does it just count on the battery settings? Does it regress down to a single level of protection? Is that why some of the inverter settings are inaccessible in this mode?

That is a good point. Not sure if the Growatt just uses the battery BMS' low voltage cutoff point, or does it perhaps pad it slightly (i.e. +1 V)? I'm wondering what is the advantage then for being able to communicate directly with the batteries, other than not having to set charge and cut-off voltages?

 

[Will Prowse]

You wouldn't happen to remember which video, would you? I'm fairly sure I've watched all of @Will Prowse's video from the last couple of months and don't recall seeing this part.


That is a good point. Not sure if the Growatt just uses the battery BMS' low voltage cutoff point, or does it perhaps pad it slightly (i.e. +1 V)? I'm wondering what is the advantage then for being able to communicate directly with the batteries, other than not having to set charge and cut-off voltages?

The advantage is the SOC is calculated with a coulomb meter on the BMS, and this SOC can control LVD and HVD instead of voltage. You can cause the disconnect to happen at 10% or 20% etc.

I think this is great for NMC or other variants, but for LiFePO4, I do not see the point. I think the communication is not worth using.

I could see some use for the communication system if you are using it in a high temp environment, or plan to push high C rates. It would be better to control charge and discharge through the inverter and not the BMS in these situations.

But used for solar and low c rate cycling, I just don't see any benefit. Some plan to increase cycle life count, but those increased estimated cycles at various DOD configurations are at a high c rate anyway. I think calendar aging will kill these packs before charging and discharging with a solar system would.

 

[FilterGuy]

You wouldn't happen to remember which video, would you? I'm fairly sure I've watched all of @Will Prowse's video from the last couple of months and don't recall seeing this part.


That is a good point. Not sure if the Growatt just uses the battery BMS' low voltage cutoff point, or does it perhaps pad it slightly (i.e. +1 V)? I'm wondering what is the advantage then for being able to communicate directly with the batteries, other than not having to set charge and cut-off voltages?

@Will Prowse already replied but.....

I went looking for the video. I did not find the one I remember, but I did find this:

 

[Dank Farrik]

The advantage is the SOC is calculated with a coulomb meter on the BMS, and this SOC can control LVD and HVD instead of voltage. You can cause the disconnect to happen at 10% or 20% etc.

Thanks for the reply Will. How does the Growatt calculate the SOC when it does not communicate with the BMS? Is it purely by voltage, or does it have some kind of shunt/hall effect current sensor built-in?

I think this is great for NMC or other variants, but for LiFePO4, I do not see the point. I think the communication is not worth using.

I'm not sure I follow why BMS communication is more beneficial for NMC vs LFP? Can you please expand on that?

But used for solar and low c rate cycling, I just don't see any benefit. Some plan to increase cycle life count, but those increased estimated cycles at various DOD configurations are at a high c rate anyway. I think calendar aging will kill these packs before charging and discharging with a solar system would.

These 48V server rack LFP batteries all seem pretty similar. Do you have any personal preferences for a specific one? EG4 vs SOK vs Jakiper for example?

 

[Solar Guy Richard]

I’m thinking about building a home power station with 2x 48V rack batteries (EG4 or SOK). Questions for the Growatt experts here regarding the Growatt SPF 3000TL LVM 48V:

1. For Setting 5 (Battery Type), if it’s set to “Li” (battery with Growatt BMS communication), Setting 2 (Max utility + solar charge current) says this:

“(If Li is selected in Program 5, this program can’t be set up)”

Why is this? What if I want to set a max current limit for solar charging?

2. If Setting 5 set to “USE” (User 1) or “US2” (User 2), does the Growatt display still show battery SOC %, or just the battery voltage?

3. In Signature Solar’s product video for the Growatt, they mentioned that you should keep the power switch in the OFF position, connect your batteries, then turn the power switch ON, otherwise the huge inrush current may damage the inverter. This implies that the Growatt has some kind of precharge circuit. Can anyone confirm?

Thanks in advance!

Hope I can shed some advice here, having set these up hundreds of times!
1 - Setting 2 is without communications. As soon as you configure comms, the battery will tell the inverter the ideal settings to charge correctly based on several factors. Additionally, you can still assign utility charging if you want to reduce that or manually set it in setting 12.
2 - USE and US2 are for different battery types. USE is for non-lithium battery where you want to manually configure settings 19-21. US2 is for a LITHIUM battery that does not have communications enabled, and still set the settings for 19-21. The battery will be displayed in voltage. Only when in LI mode will it display as a percentage (which it gets from the BMS).
3. To my knowledge, Growatt does not have a precharge circuit built in. I know the EG4 batteries we carry at Signature Solar have this built in, but honestly this is just good advice in general - not hooking up hot lines to an actively engaged system. I'll find out if there was another underlying reason for this advice.

 

[Dank Farrik]

Hope I can shed some advice here, having set these up hundreds of times!
1 - Setting 2 is without communications. As soon as you configure comms, the battery will tell the inverter the ideal settings to charge correctly based on several factors. Additionally, you can still assign utility charging if you want to reduce that or manually set it in setting 12.
2 - USE and US2 are for different battery types. USE is for non-lithium battery where you want to manually configure settings 19-21. US2 is for a LITHIUM battery that does not have communications enabled, and still set the settings for 19-21. The battery will be displayed in voltage. Only when in LI mode will it display as a percentage (which it gets from the BMS).
3. To my knowledge, Growatt does not have a precharge circuit built in. I know the EG4 batteries we carry at Signature Solar have this built in, but honestly this is just good advice in general - not hooking up hot lines to an actively engaged system. I'll find out if there was another underlying reason for this advice.

Thanks for the great info Richard! Let me give a little bit of background on why I want to be able to limit max solar charging current:

I have a pending Tesla Powerwall install in July. That will ensure that my grid tied rooftop solar system continues to produce power in an outage, and it will power my 240V devices (really just the AC, used sparingly) and non-essential circuits. I also have a Reliance Controls 6-circuit manual transfer switch (which is a solid neutral transfer switch) installed next to my sub-panel (contains all of my circuits except for AC and dryer). in my garage. The transfer switch is connected to 6 of my essential circuits, including my networking equipment, natural gas furnace, and refrigerator. I did it this way because I don't want to be 100% reliant on the Powerwall, as it can only be charged by solar. I want to be still able to power my 6 essential circuits even if I get no sunshine, as I can then charge my indoor batteries via a generator.

Here is where I ran into some initial issues. If there is sunshine, I want to charge my indoor power bank from one of the sub-panel circuits that is NOT a part of the transfer switch. I tried this with my EcoFlow Delta Max power station. As with all EF power stations, when its AC input is plugged into an outlet, it engages pass-through mode and essentially becomes a giant extension cord, which goes from a (non-transfer switch) sub-panel circuit into the transfer switch inlet, then out to 6 other sub-panel circuits. This creates multiple neutral paths, which is bad. And unfortunately I found out the hard way. Using a GFCI circuit as the AC input immediately trips the GFCI, otherwise no harm done. However, using a non-GFCI circuit as the AC input fried the inverter in the EF, as in an audible pop, smoke came out, and then the AC inverter no longer worked. So this lead me to my workaround solution, which is to use a 90V 1500W DC switching power supply that I can plug into a non-transfer switch circuit. When charging via DC, the EF does not engage pass through mode, and thus no multiple neutral paths, and I confirmed everything works well. However, the DC power supply recommends that you keep it at 80% max load for extended usage for longevity, which means I need to keep it at 1200W.

My understanding of the Growatt is that it works the same way as the EF. When plugged into an AC outlet, it goes into pass through mode (I think Growatt calls it Line Mode). To prevent the inverter from being blown up, I want to feed DC power through its solar input instead, using my DC power supply, but I want to limit the draw to 1200W. I don't see a way to limit the max solar charging current in "Li" mode, only in "US2" mode (Setting 2). I like "Li" mode because it lets me set HVD and LVD disconnect as percentages, and it lets me see the SOC as a %. I really just want to be able to remotely see what % the batteries are at without having to get out of bed and physically run into the garage to check the batteries' own display (which does show the SOC %).

 

[Solar Guy Richard]

Thanks for the great info Richard! Let me give a little bit of background on why I want to be able to limit max solar charging current:

I have a pending Tesla Powerwall install in July. That will ensure that my grid tied rooftop solar system continues to produce power in an outage, and it will power my 240V devices (really just the AC, used sparingly) and non-essential circuits. I also have a Reliance Controls 6-circuit manual transfer switch (which is a solid neutral transfer switch) installed next to my sub-panel (contains all of my circuits except for AC and dryer). in my garage. The transfer switch is connected to 6 of my essential circuits, including my networking equipment, natural gas furnace, and refrigerator. I did it this way because I don't want to be 100% reliant on the Powerwall, as it can only be charged by solar. I want to be still able to power my 6 essential circuits even if I get no sunshine, as I can then charge my indoor batteries via a generator.

Here is where I ran into some initial issues. If there is sunshine, I want to charge my indoor power bank from one of the sub-panel circuits that is NOT a part of the transfer switch. I tried this with my EcoFlow Delta Max power station. As with all EF power stations, when its AC input is plugged into an outlet, it engages pass-through mode and essentially becomes a giant extension cord, which goes from a (non-transfer switch) sub-panel circuit into the transfer switch inlet, then out to 6 other sub-panel circuits. This creates multiple neutral paths, which is bad. And unfortunately I found out the hard way. Using a GFCI circuit as the AC input immediately trips the GFCI, otherwise no harm done. However, using a non-GFCI circuit as the AC input fried the inverter in the EF, as in an audible pop, smoke came out, and then the AC inverter no longer worked. So this lead me to my workaround solution, which is to use a 90V 1500W DC switching power supply that I can plug into a non-transfer switch circuit. When charging via DC, the EF does not engage pass through mode, and thus no multiple neutral paths, and I confirmed everything works well. However, the DC power supply recommends that you keep it at 80% max load for extended usage for longevity, which means I need to keep it at 1200W.

My understanding of the Growatt is that it works the same way as the EF. When plugged into an AC outlet, it goes into pass through mode (I think Growatt calls it Line Mode). To prevent the inverter from being blown up, I want to feed DC power through its solar input instead, using my DC power supply, but I want to limit the draw to 1200W. I don't see a way to limit the max solar charging current in "Li" mode, only in "US2" mode (Setting 2). I like "Li" mode because it lets me set HVD and LVD disconnect as percentages, and it lets me see the SOC as a %. I really just want to be able to remotely see what % the batteries are at without having to get out of bed and physically run into the garage to check the batteries' own display (which does show the SOC %).

We've found the best solution to this issue is buying a battery charger to connect to the generator instead of trying to run it through the inverter. Generators in general put out pretty poor sine waves and tend to be hard on equipment. Getting a $250 battery charger is what I'd recommend, but beyond that I don't believe there are any ways of changing that setting beyond using a 3rd party shunt for %'s instead of the Growatt.

 

[Dank Farrik]

We've found the best solution to this issue is buying a battery charger to connect to the generator instead of trying to run it through the inverter. Generators in general put out pretty poor sine waves and tend to be hard on equipment. Getting a $250 battery charger is what I'd recommend, but beyond that I don't believe there are any ways of changing that setting beyond using a 3rd party shunt for %'s instead of the Growatt.

You are talking about your 48V 25A charger? It always puts out 1400W, right? No way to adjust the max output to, say, 1200W?

I did consider using a 3rd party shunt like the Victron Smart Shunt. I’ve read the Bluetooth range is not great though. Is there one that is WiFi enabled?

 

[TerryG]

I’m thinking about building a home power station with 2x 48V rack batteries (EG4 or SOK). Questions for the Growatt experts here regarding the Growatt SPF 3000TL LVM 48V:

1. For Setting 5 (Battery Type), if it’s set to “Li” (battery with Growatt BMS communication), Setting 2 (Max utility + solar charge current) says this:

“(If Li is selected in Program 5, this program can’t be set up)”

Why is this? What if I want to set a max current limit for solar charging?

2. If Setting 5 set to “USE” (User 1) or “US2” (User 2), does the Growatt display still show battery SOC %, or just the battery voltage?

3. In Signature Solar’s product video for the Growatt, they mentioned that you should keep the power switch in the OFF position, connect your batteries, then turn the power switch ON, otherwise the huge inrush current may damage the inverter. This implies that the Growatt has some kind of precharge circuit. Can anyone confirm?

Thanks in advance!

I was able to to change Setting 2 to 50A, but I don't remember how I did it. Maybe I changed Setting 5 to something other than

I’m thinking about building a home power station with 2x 48V rack batteries (EG4 or SOK). Questions for the Growatt experts here regarding the Growatt SPF 3000TL LVM 48V:

1. For Setting 5 (Battery Type), if it’s set to “Li” (battery with Growatt BMS communication), Setting 2 (Max utility + solar charge current) says this:

“(If Li is selected in Program 5, this program can’t be set up)”

Why is this? What if I want to set a max current limit for solar charging?

2. If Setting 5 set to “USE” (User 1) or “US2” (User 2), does the Growatt display still show battery SOC %, or just the battery voltage?

3. In Signature Solar’s product video for the Growatt, they mentioned that you should keep the power switch in the OFF position, connect your batteries, then turn the power switch ON, otherwise the huge inrush current may damage the inverter. This implies that the Growatt has some kind of precharge circuit. Can anyone confirm?

Thanks in advance!

I was able to change setting 2 = 50A and I'm using setting 5 = Li. I don't remember exactly how I did it. Maybe I changed setting 5 to something other than Li, then changed setting 2, and then changed setting 5 back to Li. I also remember that changing setting 11 (now 30A) affects what values you can set for setting 5, or vice versa. I'm using SBU and OSO modes and three LiFePower4 batteries. I have the 24V inverter.

 

[Dank Farrik]

I was able to to change Setting 2 to 50A, but I don't remember how I did it. Maybe I changed Setting 5 to something other than

I was able to change setting 2 = 50A and I'm using setting 5 = Li. I don't remember exactly how I did it. Maybe I changed setting 5 to something other than Li, then changed setting 2, and then changed setting 5 back to Li. I also remember that changing setting 11 (now 30A) affects what values you can set for setting 5, or vice versa. I'm using SBU and OSO modes and three LiFePower4 batteries. I have the 24V inverter.

Interesting. Thanks for sharing!

 

[schmism]

My sig has a link to how to DIY chargers from server power supplies.

 

[cliffgrimes]

We've found the best solution to this issue is buying a battery charger to connect to the generator instead of trying to run it through the inverter. Generators in general put out pretty poor sine waves and tend to be hard on equipment. Getting a $250 battery charger is what I'd recommend, but beyond that I don't believe there are any ways of changing that setting beyond using a 3rd party shunt for %'s instead of the Growatt.

Do you charge the entire battery bank at the same time or just do individual batteries, one at a time?

 

[Solar Guy Richard]

Do you charge the entire battery bank at the same time or just do individual batteries, one at a time?

Once batteries are balanced you can do them all at once. Normally to balance you do 1 at a time.

 

[Herb]

Hello, I did a search on server type batteries, since I'm considering pulling the trigger on 2 of these things. I would like to get some feedback on the ones that Signature Solar offers in their web store, one of my main concerns is with the communication, will they communicate with the Growatt all in one 3K, 48v model? Will the Growatt provide their correct SOC? Are there any issues? Looking at the 5Kw ones, since they are within my budget. Comments?