Help me scale up my back-up solution

Iwojima said:
Would it be drawing directly from the batteries even when there is AC? Seems to be 25w-30w per battery.

Before I had the cable from the Pi to the batteries (ie just the Pi to inverter) this was was not reflected in the "Battery Power" section of SolarAssitant. It was a flat 0 mostly while on AC.

In fact I have the exact moment logged where I plugged the Pi to battery cables in and the 25w draw per battery becomes apparent.
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Yeah, no it shouldn't if on AC. Maybe minus value equals charging so maybe top balancing? I don't know, I don't have any experience with this. Was just pointing out the voltages/SOC didn't make sense.
 
wingnut771 said:
Yeah, no it shouldn't if on AC. Maybe minus value equals charging so maybe top balancing? I don't know, I don't have any experience with this. Was just pointing out the voltages/SOC didn't make sense.
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Yeah, the reason why it concerns me is when I see the following behavior as well.

Over the course of every 60 to 90min the battery voltage drops from 53.2v down to 50.3v while on grid power. Inverter then throws some current at the battery to get it back up to 53.2v.

1683997441596.png
 
wingnut771 said:
What settings are you using?
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Using the built-in Pylontech BMS controlled program (Menu 5 set to PYL)

Only other things I changed was to UPS mode (from APL), max AC charge current to 30A, cut-off of the secondary output to 95% SOC and low DC cutoff to 20% SOC.

Output Source Prio is set (for now) to Utility, Solar, Battery
 
Iwojima said:
Using the built-in Pylontech BMS controlled program (Menu 5 set to PYL)

Only other things I changed was to UPS mode (from APL), max AC charge current to 30A, cut-off of the secondary output to 95% SOC and low DC cutoff to 20% SOC.

Output Source Prio is set (for now) to Utility, Solar, Battery
Click to expand...
I think its the Kodak causing this as I think its an Axpert thing. @TheChamp (Axpert guru), how do we stop these mini cycles?

I have a suspicion that it's because of this:
1684003254680.png

Maybe try other battery settings like AGM or user for example?

I assume you have no solar?
 
wingnut771 said:
I think its the Kodak causing this as I think its an Axpert thing. @TheChamp (Axpert guru), how do we stop these mini cycles?

I have a suspicion that it's because of this:
View attachment 1523725

Maybe try other battery settings like AGM or user for example?

I assume you have no solar?
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No solar for now. Scheduled to get some panels up in June.
 
Iwojima said:
I'll give it a go, but let's see what @TheChamp and @AchmatK have to offer before I do :D
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I would definitely not use agm or other standard lead acid .setting on pylontech because it has one less cell you are one cell voltage over what it actually needs

Edit that is only ok on 51.2v 16s batteries
 
Iwojima said:
Would it be drawing directly from the batteries even when there is AC? Seems to be 25w-30w per battery.

Before I had the cable from the Pi to the batteries (ie just the Pi to inverter) this was was not reflected in the "Battery Power" section of SolarAssitant. It was a flat 0 mostly while on AC.

In fact I have the exact moment logged where I plugged the Pi to battery cables in and the 25w draw per battery becomes apparent.
Click to expand...
Some bms's do like a mini discharge cycle if it the voltage is over what the bms like

Have seen this happen on mine if the voltage overshoots a bit
 
Iwojima said:
Yeah, the reason why it concerns me is when I see the following behavior as well.

Over the course of every 60 to 90min the battery voltage drops from 53.2v down to 50.3v while on grid power. Inverter then throws some current at the battery to get it back up to 53.2v.

View attachment 1523691
Click to expand...
Set the float on 50.5v and it will stop doing this charge rest charge cycle
 
wingnut771 said:
50.5V / 15 = 3.36V
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Yea the float voltage on lithium is irrelevant actually

Apart from one thing ie inverter have logic to say when should a recharge be done

ie if batteries are full they will rest

And then when load shedding hits and the voktage drops x amount under float the charging logic is woken up, so next time power cones on it will recharge

So by having a float set the same as charge as many do , and many manuals state you should do

Once the battery is full it stops charging and as the rest voltage is quite a bit lower

Just resting voltage triggers another charge cycle

Rinse repeat

Now yes that float equal to charge has its uses

ie to be able to use solar more effectively without mini Cycling for charge controller to kick in ie on victrons
 
I just found that 50.5v works nice for me ie my cells rest at 3.36v ish

Which i can pick up via battery coms so just set mine to match where ny cells rest naturally

I have a 15s battery similar to pylontech
 
wingnut771 said:
50.5V / 15 = 3.36V How is that fully charged?
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Resting

I charge to 53.5v (after checking my battery via coms i can see when it is full and set the lowest value to reach full to take it easy on batteries and to compensate for overshoot ie you can go to 54.6v ) 50.5 is then to where mine settles can set float up to 51.75v

but like i said float is kinda irrelevant as long as it is high enough to trigger a charge cycle after load shedding

So what you want is have it low enough that resting doesn't trigger a charge cycle
 
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leon.davibe said:
Yea the float voltage on lithium is irrelevant actually

Apart from one thing ie inverter have logic to say when should a recharge be done

ie if batteries are full they will rest

And then when load shedding hits and the voktage drops x amount under float the charging logic is woken up, so next time power cones on it will recharge

So by having a float set the same as charge as many do , and many manuals state you should do

Once the battery is full it stops charging and as the rest voltage is quite a bit lower

Just resting voltage triggers another charge cycle

Rinse repeat

Now yes that float equal to charge has its uses

ie to be able to use solar more effectively without mini Cycling for charge controller to kick in ie on victrons
Click to expand...
but the cell reading is 3.4V.
1684075828849.png
 
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