Growatt spf Not Seeing PV In The Morning

[timselectric]

Andy (off grid Garage) is currently raising his settings. He wasn't getting enough balancing on his cells.

 

[apctjb]

So quick question, and maybe I missed it, but where d I find the most updated firmware and ShineBus downloads?

I would like to know as well, I haven't been able to find a download section on Growatt website, have gotten mine by contacting growatt support.

 

[apctjb]

As you are a fan of Andy's, then possibly you missed this video.

Thanks, I will give it a watch.

Do the older Daly BMS even have balancing?

 

[apctjb]

Great video. I am going to have to watch the ones that follow but my first impression is that charging to 54.5 absorption, 54 float is not so bad. It brings cells up to 3.4V but avoids run away cells. (probably not all of them, but I cant see that remotely on solar assistant, I wish they would add that feature).

Would love to hear more about why having cells that are not perfectly balanced could possible lead to greater degradation than charging at higher voltages? The lesser of two evils?

Thanks!!!

 

[timselectric]

Great video. I am going to have to watch the ones that follow but my first impression is that charging to 54.5 absorption, 54 float is not so bad. It brings cells up to 3.4V but avoids run away cells. (probably not all of them, but I cant see that remotely on solar assistant, I wish they would add that feature).

Would love to hear more about why having cells that are not perfectly balanced could possible lead to greater degradation than charging at higher voltages? The lesser of two evils?

Thanks!!!

It's not so much about degradation. As it applies to available capacity.
If never balanced, they can be very far apart.

 

[Zwy]

Great video. I am going to have to watch the ones that follow but my first impression is that charging to 54.5 absorption, 54 float is not so bad. It brings cells up to 3.4V but avoids run away cells. (probably not all of them, but I cant see that remotely on solar assistant, I wish they would add that feature).

Would love to hear more about why having cells that are not perfectly balanced could possible lead to greater degradation than charging at higher voltages? The lesser of two evils?

Thanks!!!

The pack voltage is the sum of cell voltage. Cells not balanced vary in SOC/voltage. Some still in the flat part of the charge/discharge curve, others into the knee areas at the top and bottom of the curve.

This affects capacity. Running a pack down to the lower end of SOC will find cells that run way ahead of the others to low discharge limits. Same with charging, you can have cells that will run way ahead of others. This can affect single cell lifespan.

I have a Daly in my truck camper and yes, it balances cells. I also have the display and can read individual cell voltages at a glance. The Daly I use is a Smart Daly. It does not start balance until cells are above 3.40V

I would increase your bulk and float by about 0.5V minimum. 54.5V float will just get to 3.40V per cell and enable balancing. The problem with the Growatt not starting charging will probably go away also. The Growatt will charge in bulk until that voltage setting is hit, then it will let pack voltage drop to float and maintain it there. There is not any absorption charge taking place after bulk so you have to use float to get absorption charge. 3.4V per cell will get the pack into the 95% SOC which is perfectly fine. It takes some absorption to get cells above the 90% SOC. Bulk charge is not absorption, you will notice cell voltage drops off once bulk charge is finished.

 

[Zwy]

Andy (off grid Garage) is currently raising his settings. He wasn't getting enough balancing on his cells.

I haven't watched his videos in some time. Last video I watched he was playing with some modified Heltec balancer.

 

[apctjb]

I would increase your bulk and float by about 0.5V minimum. 54.5V float will just get to 3.40V per cell and enable balancing. The problem with the Growatt not starting charging will probably go away also. The Growatt will charge in bulk until that voltage setting is hit, then it will let pack voltage drop to float and maintain it there.

Thanks, I appreciate the input.

The charging algorithm will work as you describe as long battery voltage drops below float setpoint during T2 Float time. But if voltage stays above float then float times out and charging stops. If the the unit is set to follow loads, PV will supply the loads but no charging will occur, and the next day MPPT charging will not resume.

So I suspect you are right that raising absorption and float settings higher eliminates the issue. The tradeoff is closer to the knee of the curve, higher cell voltages and potential for cell to run to 3.65, which has happened to me.

• The charging algorithm ceases solar input if the battery voltage remains higher than the float voltage after absorption charging is complete.

 

[Zwy]

Thanks, I appreciate the input.

The charging algorithm will work as you describe as long battery voltage drops below float setpoint during T2 Float time. But if voltage stays above float then float times out and charging stops. If the the unit is set to follow loads, PV will supply the loads but no charging will occur, and the next day MPPT charging will not resume.

So I suspect you are right that raising absorption and float settings higher eliminates the issue. The tradeoff is closer to the knee of the curve, higher cell voltages and potential for cell to run to 3.65, which has happened to me.

• The charging algorithm ceases solar input if the battery voltage remains higher than the float voltage after absorption charging is complete.

If your cells have been run for a long period of time without adequate balancing, you probably will have a runner or two if you raise charging voltage. You could try raising by 0.1V per day for 5 days or 0.05V for 10 days. This will allow some balancing to occur.

If these cells won't balance well with passive balancing, then you will need to source an active balancer.

 

[apctjb]

If your cells have been run for a long period of time without adequate balancing, you probably will have a runner or two if you raise charging voltage. You could try raising by 0.1V per day for 5 days or 0.05V for 10 days. This will allow some balancing to occur.

If these cells won't balance well with passive balancing, then you will need to source an active balancer.

Good suggestion; when I get back to the site and can monitor individual cell voltages will give it a try. If you have a recommendation for a good active balancer would be good to know.

 

[Zwy]

Good suggestion; when I get back to the site and can monitor individual cell voltages will give it a try. If you have a recommendation for a good active balancer would be good to know.

I don't use one but Andy has plenty of videos with his experience with them.

 

[apctjb]

For those that want to give it a try; this is the firmware Growatt says will correct the issue of PV not resuming. Caution; My attempt to flash this firmware crashed and took out all MPPT functionality. Would not charge. Had to revert to earlier version to get MPPT tracking functionality back. Curious to hear if it works for anyone.

https://drive.google.com/file/d/18s3iAq8eBRhn9xhie4L6z8dKx0WRpdWE/view?usp=drive_link