Help me scale up my back-up solution

I would lower the charge voltage a bit

From my bms's behaviour i pick up that it doesn't actually like the recommended 54.6v the manual states i should use

ie if i push my battery to that value the pack voltage flashes red and it triggers a mini discharge cycle to lower pack voltage

And then when it drops to below 53ish if i remember correctly

It allows the pack to be able to charge again

So from what i have experienced 3.53-3.55v x15 as that is when i don't see this behaviour

And attain a full charge without problems
 
Just to add,the Growatt SPF *should* blend,I recently installed Solarix Sacolar 5kw units (12k per) that are basically their clones and they do blend
 
PsyWulf said:
Just to add,the Growatt SPF *should* blend,I recently installed Solarix Sacolar 5kw units (12k per) that are basically their clones and they do blend
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Yea i have seen a video where someone uses a growatt with only panels and utility ie no batteries , and then it blends by using the utility to cover what the panels come up short

As far as i heard only the high voktage mppt models can run like this without batteries
 
leon.davibe said:
Yea i have seen a video where someone uses a growatt with only panels and utility ie no batteries , and then it blends by using the utility to cover what the panels come up short

As far as i heard only the high voktage mppt models can run like this without batteries
Click to expand...
The 450V DC bus models? Makes sense
 
leon.davibe said:
I would lower the charge voltage a bit

From my bms's behaviour i pick up that it doesn't actually like the recommended 54.6v the manual states i should use

ie if i push my battery to that value the pack voltage flashes red and it triggers a mini discharge cycle to lower pack voltage

And then when it drops to below 53ish if i remember correctly

It allows the pack to be able to charge again

So from what i have experienced 3.53-3.55v x15 as that is when i don't see this behaviour

And attain a full charge without problems
Click to expand...
Just some details regarding what the inverter and BMS settings are when set to use the PYL program:

1684084378832.png
(Ignore the max charge current value above, as previously established this does fluctuate based on the BMS)

1684084313938.png


EDIT:
Caught it as it started a new mini-cycle. I certainly hope this 3.6v figure is just 3.55v rounded up:
1684084698710.png
 
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Iwojima said:
Just some details regarding what the inverter and BMS settings are when set to use the PYL program:

View attachment 1524051
(Ignore the max charge current value above, as previously established this does fluctuate based on the BMS)

View attachment 1524047


EDIT:
Caught it as it started a new mini-cycle. I certainly hope this 3.6v figure is just 3.55v rounded up:
View attachment 1524053
Click to expand...
3.6v is perfectly fine 3.65 is what cell manufacturers recommend so a pack voltage with 15cells upto 54.75v would be within the cell accepted charge voltage

The high float is what is causing the mini charge cycles

Well technically it isn't charging much
It just pushes the steep part voltage and settles back down

I observed this behaviour when i got my shoto which is also a 15s thus has the same voltages

If you drop that float you will lose the mini cycles

ie a lithium is both full at charging 3.6-3.65 and resting 3.37-3.45v

So no need to keep it at 3.6v if not needed
 
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You will get more balancing time
As most bms only balance while charging

They may have this program this way to make up for pathetic balance currents by doing this micro cycle thing to induce more balancing sessions
 
Iwojima said:
  • Mecer 3kw/24v unit
  • 4x180ah AGM batteries (2x2 config)
  • Powers everything except the geyser and electric stove
  • Caution applied during loadshedding hours to ensure no kettles/hairdryers/dishwashers are used
  • No solar
Click to expand...

Sorry for the hijack but something like this seems to be what i require, i just need to keep the lights on and my home office (PC, laptop, extra screens) going along with the router and CPE. Having the microwave up will also help.

Is this overkill?
 
ShloshMalosh said:
Sorry for the hijack but something like this seems to be what i require, i just need to keep the lights on and my home office (PC, laptop, extra screens) going along with the router and CPE. Having the microwave up will also help.

Is this overkill?
Click to expand...
Perfectly adequate, but your choice of battery(ies) will determine your ability to use your microwave. You do not want to discharge at any given time more than the batteries are rated for.

e.g. Let's say your base load is 400w and your microwave is 2000w for a total of 2400w. 2400w @ 24v = 100A. So you'd want a battery setup that is rated to do 100A continuous (not peak) discharge.
 
Iwojima said:
Perfectly adequate, but your choice of battery(ies) will determine your ability to use your microwave. You do not want to discharge at any given time more than the batteries are rated for.

e.g. Let's say your base load is 400w and your microwave is 2000w for a total of 2400w. 2400w @ 24v = 100A. So you'd want a battery setup that is rated to do 100A continuous (not peak) discharge.
Click to expand...
Thanks, the microwave is a nice to have for me as i have a gas stove. Happy to forgoe that if its going to increase costs. the fridge and freezer might be more of a priority especially if 4 hour loadshedding sessions become more frequent
 
ShloshMalosh said:
Thanks, the microwave is a nice to have for me as i have a gas stove. Happy to forgoe that if its going to increase costs. the fridge and freezer might be more of a priority especially if 4 hour loadshedding sessions become more frequent
Click to expand...
Honestly unless you're sitting with a dinosaur of a fridge/freezer or have them constantly open and closed they tend to sip power.

Yes, when the compressor kicks in there is an inrush of current and you will might on occasion exceed the 3kw rating of the inverter momentarily before it settles, but the inverter will be rated for something like "2x times rated power for 5s". More than enough time to handle this.
 
Iwojima said:
Honestly unless you're sitting with a dinosaur of a fridge/freezer or have them constantly open and closed they tend to sip power.

Yes, when the compressor kicks in there is an inrush of current and you will might on occasion exceed the 3kw rating of the inverter momentarily before it settles, but the inverter will be rated for something like "2x times rated power for 5s". More than enough time to handle this.
Click to expand...
Thanks this has been very helpful
 
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