Growatt - Odd behavior

debron55

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I've been watching this thread, and suspected this was going to be their response.

I am curious what you happen if you responded with something like: "My battery supplier is interested in making their BMS compatible with the Growatt inverter. They asked for documentation of the communication protocol - could you please provide? Thanks."

I would be interested to see that documentation. Hardware that can speak RS485 is cheap, and relatively simple to engineer. I know that doesn't directly resolve the issue here, but I'd love to build something that connects between the Growatt and BMS (Overkill already has documentation on its TTL UART interface, has Arduino libraries, etc.)
Sorry I have been absent so long - DataCenter duties were extreme this last month - I did send them exactly that question RE: can they provide documentation regarding the comm protocol. Will let the group know their response.
 

debron55

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Sorry I have been absent so long - DataCenter duties were extreme this last month - I did send them exactly that question RE: can they provide documentation regarding the comm protocol. Will let the group know their response.
SO - crazy as it may seem they provided the communication protocol documents.
 

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fazeshift

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Sorry I have been absent so long - DataCenter duties were extreme this last month - I did send them exactly that question RE: can they provide documentation regarding the comm protocol. Will let the group know their response.
SO - crazy as it may seem they provided the communication protocol documents.

No need to apologize. (I have past experience with the demands of the IT field too)

Wow, that's awesome they did provide some protocol documentation. I skimmed through - looks useful. I'm going to play around translating the non-English parts, and see if this idea is feasible.
 

fazeshift

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Translated docs attached, if anyone else is curious. Please excuse the table formatting that got trashed in one - looks like most of that was already English.

There is a lot to digest. I should probably create a new thread, as to not derail the existing discussion here.
 

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solarstuff

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Just helped someone configure two of these in parallel 120/240V operation, and he experienced something similar.

Prior to final configuration, the unit behaved as the OP described. After reconfiguration and the complete hard "reboot" necessitated by wiring changes that completely disconnected the units from all sources, proper operation has initiated:

Bulk to bulk
Hang out there awhile.
Drop to float.
Hold float and power loads with solar.

IMHO float should not be above 27.2 as floating them above 3.4V/cell is never recommended and can damage cells.

View attachment 50656
View attachment 50657
View attachment 50658
Are these numbers safe for AGM? The red numbers, in a 24v system?
 

coolbz

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HELP! I'm getting BMS cell over-voltage warning almost everyday.

I'm running SBU mode with US2, CV and float volt both at 55v per Ian suggestion. Everyday solar support load as first priority and charge battery when it has surplus power during the day. Once battery is charged to CV, Growatt does stop charge and then battery volt drops between 53-54v, but then Growatt started to charge battery again toward CV volt. This repeat several times in afternoon. Then two battery cells start to drift higher until one trips BMS to shut off charge. Afterawhile, that cell's volt drop to the point so BMS recovers. This is not normal. Did I do something wrong or Growatt or battery having issues?
 

Lt.Dan

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If the battery is out of balance, its not an inverters fault. Look into why the battery is going out of balance. Need a top balance? One cell bad?
 

coolbz

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If the battery is out of balance, its not an inverters fault. Look into why the battery is going out of balance. Need a top balance? One cell bad?
I believe there are at least two issues.

The main issue apparently is one battery cell not perfectly balanced, or it has lower capacity so it's voltage shot up and down near the high and low charge state. I bought battery from batteryhookup and the shipping padding was missing at side and bottom of packages, most of all padding was on the top of box, which could easily cause damage if the box was dropped from a feet above ground. If one or few cylinders out of 20 loose connection from solder, it will definitely cause lower capacity and never able to achieve both top and bottom balance.

The second issue is still around Growatt inverter, which seem to keep trying to charge battery during the day as long as battery voltage is lower than CV.
 

Zwy

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I believe there are at least two issues.

The main issue apparently is one battery cell not perfectly balanced, or it has lower capacity so it's voltage shot up and down near the high and low charge state. I bought battery from batteryhookup and the shipping padding was missing at side and bottom of packages, most of all padding was on the top of box, which could easily cause damage if the box was dropped from a feet above ground. If one or few cylinders out of 20 loose connection from solder, it will definitely cause lower capacity and never able to achieve both top and bottom balance.

The second issue is still around Growatt inverter, which seem to keep trying to charge battery during the day as long as battery voltage is lower than CV.
Lower the float to 0.5V less than bulk. I'd also consider lowering bulk charge 0.5V and see if the cell continues to be a runner that trips the BMS.

Most here use USE and not USE 2.

And yes, top balance might be required.
 

coolbz

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Lower the float to 0.5V less than bulk. I'd also consider lowering bulk charge 0.5V and see if the cell continues to be a runner that trips the BMS.

Most here use USE and not USE 2.

And yes, top balance might be required.
Thanks for all advises! I have done all of these and it is very helpful. The only issue remaining seem to be one or two battery cells have smaller capacity so they tend to go up and down earlier than others if I use aggressive parameters (higher bulk charge and lower discharge). For now, I'm not worry too much and am using conservative parameters.

My next project would be crypto mining and going to check Will's new videos. May the sun god shine forever!
 

JohnTHQ

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Jul 27, 2021
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Looking forward to seeing what comes of this! And the translations. Thanks @fazeshift

Buying a Growatt this week.
Like wise. I am just waiting for my copper to show up and ill start my install. ive been staring down my 3000 24v lvm with seething eyes *fingers crossed*
 

AakiraA

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You are talking about a completely different issue. The Growatt has a goofy AC charger and has nothing to do with PV charging parameters/performance.

Growatt AC charger turns on at the low voltage and stops immediately upon attaining peak voltage. It does not have bulk/absorption set points but simple on/off voltages.

In order to have your unit function as a useful UPS, you would have to set both values to nearly the same number, and the "on" value should be at the float voltage of the particular battery.
Im having a problem with my 48v units. I have 2 in split phase and my battery will last 3 min then the grid takes over the load and charges my battery then once fully charged back to battery the 3 min back to grid. I have 2- 24v batteries set as 48v. Then manual recommends 400AH could my problem be that I only have 100?
I had 8 harbor freight batteries set to 48V and I was able to get 1 solid hours out of those Im told from Evo Battery that I should be getting at least 2.5 hours with the amount of energy Im using.

Ive tried everything, Ive called and emailed Growatt (only received 1 reply which didnt help) Ive been talking to Evo Battery and we cant figure it out......help......please....anyone
 

Zwy

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Im having a problem with my 48v units. I have 2 in split phase and my battery will last 3 min then the grid takes over the load and charges my battery then once fully charged back to battery the 3 min back to grid. I have 2- 24v batteries set as 48v. Then manual recommends 400AH could my problem be that I only have 100?
I had 8 harbor freight batteries set to 48V and I was able to get 1 solid hours out of those Im told from Evo Battery that I should be getting at least 2.5 hours with the amount of energy Im using.

Ive tried everything, Ive called and emailed Growatt (only received 1 reply which didnt help) Ive been talking to Evo Battery and we cant figure it out......help......please....anyone
What type of batteries?

List your model of inverter and all of the settings on it.

How many amps are you seeing on the shunt when units are powering loads?
 

izmail

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Dec 8, 2021
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If what is said here about Growatt stopping charge when battery is full-then system can be loosing few kWh from solar. In my simple solar setup- MPPT controller, battery and inverter - looks like MPPT is doing both - charging battery and running my pool pump (when sun is good of course). 10 amps goes to pump, rest to the battery. When battery is full, current drops to 10 to keep pump running - for 3-4 hours. In case of Growatt all this energy is lost and also battery would start discharging and charging , adding unnecessary cycles. To make my system Growatt-like, I added a simple $30 Voltage Monitoring Relay and $50 ATS ( very well built switch by the way). Relay turns inverter off when battery goes below 23.8v ( you can set it to any other value) and ATS switches to grid power. When battery raises to 28.4 ( or any other number of your choice), it turns inverter on and ATS switches to battery. I'm also planning to add a small cheap charger to keep battery charged at night. Total for the system $400 inverter + $30 relay +$50 ATS+$99 MPPT+ $30charger is about $600. 30% less the Growatt. It is not as convenient as one box on the wall ( I actually fitted my system l in an old 20x20 box, so I also have just one box on the wall), but you have full control and can replace failed components instead of replacing a $900 unit if it fails.. And since this is a hobby, next step would be to add a cheap $100 Teco PLC - to make it very fancy.
This PLC has 2 analog voltage inputs, so it may be possible to control system based on charging current, time of the day, calendar, etc.
 

wild01

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Feb 18, 2021
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I'm trying to set up a 6000t right now and from what I'm seeing these units just don't float well AT ALL. My mpp lv5048 will float right along with almost no deviation on the amp meter while the growatt will rapidly change from -.3** to +.5** it also goes about .5v higher than my set bulk setpoint before it starts floating.
 
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MIke oglesby

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Oct 28, 2021
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Have been following this thread quite a while and trying to optimize Growatt settings to use 50% of battery capacity, while harvesting as much solar as possible. I am using USE2 with bulk/float set at 58V, UPS mode. I have set back to grid at 51.2V. My problem is timing my back to grid times after solar drops out and battery reaches 51.2V. Growatt spf 3000tl lvm-es, husky 48v battery so no BMS communication with Growatt. 4K solar. As you see the solar does support the loads after battery is full. I can't find the correct settings to keep battery supplying loads until the 51.2 point where it should go back to grid. I am using PV load priority and PV battery charge priority.
 

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Agmills

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thanks for the info and ideas. I do believe I have figured out what the issue was. Through looking over a few others settings I noticed everyone that was working had used USER as the battery type ( also called USE). There is a new setting added in a recent firmware called USE2. ANd allegedly this was the preferred for LifePo4. FOr me at least this did not prove to be the case. For me USE2 would not allow any difference between Bulk and float. And there may be other things that USE2 does that were not as discoverable. THere is basically no documentation that I could discover for this setting. Without the unit being able to go to a float different than bulk the unit was alwas set to float at the same voltage. When this would happen the system would essentially say (or at least it seemed to me) ... I have hit bulk and would like to settle down to float and get into a balance with the overall consumption . But for some reason it did not process that sort of balance level as being attainable so it would simply say ok ... I've hit my voltage shut off the solar panels. The system would shut off the panels until the batteries were drained to their switch to utility level . This could take hours. I had tried heavier loads - I mean 25% was to me a reasonable load that would show me something.. and it had no effect. Going to USE setting for battery type hit the mark perfectly and the unit is behaving as hoped.

View attachment 51085
Ok I’ve been reading your comments guys. USE is for non BMS batteries and USE2 is for batteries with BMS. The reason you cannot change the 19,20 values is when it is configured properly it will default to a 16s setup which is 54.6 for both values I think that’s the setting. If you CORRECTLY wire the canbus/rs485 port to the BMS port on inverter in USE2 mode it will then take readings from the bms of the battery. If you have cells that peak over it will cause that individual battery to shut down until cell has settled which is why USE mode allows you to set it reguardless but do not connect the canbus/rs485 to the inverter BMS port in USE mode
 
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Agmills

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Thanks for the response - Lithium setting on the growatt is only for use of THEIR battery - it has a comunications wire that plugs into the growatt.
No . It works with others as long as bms is compatible ex Rosen batteries work .
 

MIke oglesby

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This is the charge curve from solar to battery with my spf 3000tl lvm-es, Husky 48v battery so no BMS communication with Growatt. The solar continues to power the loads until the solar is inadequate. Does this look right?
 

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