GROWATT AXE C-1 battery.

[Mannfamilywoodworks]

IMO, over ~54.7v or so, is starting to rise into the knees and around ~ +95% capacity. If the axe is like the bms in the basic eg4, it will push the inverter to charge close to 58v, which is way up into the knees. Not a lot of power up there. Not that good on the battery either. Why the inverter is reading different voltages at the same %soc, don't know. Maybe flaky data connection? Have you confirmed the voltage reading with a multimeter?

In post #10, you are importing power from the grid, or in this case, a generator.

If it were mine, it would be going back to SigSolar.

What’s the knees?

 

[Mannfamilywoodworks]

If it were mine, it would be going back to SigSolar.

I’m working on that haha

 

[Mannfamilywoodworks]

I’m afraid to hook a multi meter up to this when it has 48v+ being output in all honesty

 

[Kornbread]

What’s the knees?

Best chart I could find on short notice. See how the meat of the output is in the middle around 3.2'ish volts? People argue over the dangers of 48v setups, just don't let a wire, or something conductive, cross both leads.

 

[Mannfamilywoodworks]

Best chart I could find on short notice. See how the meat of the output is in the middle around 3.2'ish volts? People argue over the dangers of 48v setups, just don't let a wire, or something conductive, cross both leads.
View attachment 105687

Okay I see. So why do people call it the knees?

 

[Mannfamilywoodworks]

People argue over the dangers of 48v setups, just don't let a wire, or something conductive, cross both leads.

I would imagine it would fry my multimeter and hurt me if I touched both ends of multimeter to battery terminals on inverter. Am I wrong?

 

[Kornbread]

Shouldn't hurt the multimeter as that's what it is made for. Set it to dc volts, one probe on the neg, one probe on the pos, verify the reading on the growatt is in agreement to the multimeter. If I were hot and sweaty, I'd not want to push my luck touching the batteries, but so far, knock on wood, I've not had any kind of shock from them. Be mindful, the inverter outputs 120/240v ac and the pv array can be generating +100v dc, both can certainly be deadly.

 

[timselectric]

Tim where ya at!

Sorry
12 hour work day, today. And yes, it's Saturday. lol
If you set the Growatt to LI battery. It requires communication with the BMS. It has preset charging parameters. But, also takes its que from the BMS.
I also agree that the preset charging voltages are too high for the health of the cells. This is why I no longer use communications. I choose my own settings in "USER". I have played around with it for a while now, and settled on 57v bulk and 56v float/absorption.
This seems to get full capacity and not be too aggressive.
I don't get to full charge every day. If you do, you might want to go with slightly lower settings.

Edit: corrected
I mistakenly typed "USE2" instead of "USER"

 

[Mannfamilywoodworks]

Sorry
12 hour work day, today. And yes, it's Saturday. lol
If you set the Growatt to LI battery. It requires communication with the BMS. It has preset charging parameters. But, also takes its que from the BMS.
I also agree that the preset charging voltages are too high for the health of the cells. This is why I no longer use communications. I choose my own settings in "USE2". I have played around with it for a while now, and settled on 57v bulk and 56v float/absorption.
This seems to get full capacity and not be too aggressive.

jeez! I thought woodworking was bad.
Growatt is set to LI battery.
I am communicating with the bms.
I think I’ve figured most of this out.
Do you have the growatt 6k or 12k model?

 

[Mannfamilywoodworks]

Shouldn't hurt the multimeter as that's what it is made for. Set it to dc volts, one probe on the neg, one probe on the pos, verify the reading on the growatt is in agreement to the multimeter. If I were hot and sweaty, I'd not want to push my luck touching the batteries, but so far, knock on wood, I've not had any kind of shock from them. Be mindful, the inverter outputs 120/240v ac and the pv array can be generating +100v dc, both can certainly be deadly.

Aren’t they fused at 10amps?

 

[timselectric]

jeez! I thought woodworking was bad.
Growatt is set to LI battery.
I am communicating with the bms.
I think I’ve figured most of this out.
Do you have the growatt 6k or 12k model?

SPF-5000-ES

 

[Mannfamilywoodworks]

I just saw someone say
“two is one and one is none”

Speaking about these batteries.
I’m assuming I should buy another battery and get my system up to 10KWH opposed to 5KWH

 

[Mannfamilywoodworks]

SPF-5000-ES

Pretty much the same as the 6000t? Settings wise

 

[timselectric]

Pretty much the same as the 6000t? Settings wise

Very similar.
Almost exact, with battery settings.
For most AIO's.

 

[Mannfamilywoodworks]

Very similar.
Almost exact, with battery settings.
For most AIO's.

I’m sorry I’m trying to stay in these loops. What is AIO’s.
What is the reason for float voltage? Does this charge the battery to that voltage and then restrict anymore from being charged?

 

[timselectric]

AIO = All In One (Inverter, solar charger, AC charger, and transfer switch)
Float is a term used for lead acid batteries.
Absorption is actually what LFP batteries benefit from.
Float and Absorption are the same process.
Holding a constant voltage, so the battery will take the last bit of full charge. Also gives the BMS time to balance the cells in the knee.

 

[timselectric]

Sorry
12 hour work day, today. And yes, it's Saturday. lol
If you set the Growatt to LI battery. It requires communication with the BMS. It has preset charging parameters. But, also takes its que from the BMS.
I also agree that the preset charging voltages are too high for the health of the cells. This is why I no longer use communications. I choose my own settings in "USER". I have played around with it for a while now, and settled on 57v bulk and 56v float/absorption.
This seems to get full capacity and not be too aggressive.
I don't get to full charge every day. If you do, you might want to go with slightly lower settings.

Edit: corrected
I mistakenly typed "USE2" instead of "USER"

Corrected post.
Sorry,
I was very tired.

 

[Mannfamilywoodworks]

AIO = All In One (Inverter, solar charger, AC charger, and transfer switch)
Float is a term used for lead acid batteries.
Absorption is actually what LFP batteries benefit from.
Float and Absorption are the same process.
Holding a constant voltage, so the battery will take the last bit of full charge. Also gives the BMS time to balance the cells in the knee.

Thanks Buddy. Makes more sense

 

[JoeHam]

What’s the knees?

If you look at the discharge curve you will see the very sharp turns in the voltage curve that look like a bent knee.

There is very little energy to be had above or below those bends.

Most folks try to stay in between them only using approximately the 10% - 90% part of the curve.

It is generally accepted that this will extend the life of your battery.

 

[Mannfamilywoodworks]

If you look at the discharge curve you will see the very sharp turns in the voltage curve that look like a bent knee.

There is very little energy to be had above or below those bends.

Most folks try to stay in between them only using approximately the 10% - 90% part of the curve.

It is generally accepted that this will extend the life of your battery.

Okay Thankyou! I’m learning so
Much. I appreciate you!!!!
If calibration is needed which it seems my battery needed would it stay in this float voltage period for a long time?
I set the charge cut off to %100 to deep cycle the battery.
Low voltage cutoff is %30
I was told to do this for 7 days by sig solar