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MakeSkyBlue SCC for LFP

Roniya

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Jun 2, 2022
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I recently updated my battery bank from Lead Acid to LiFePO4 (280Ah 8s) and I'm using a MakeSkyBlue (V118) 60A SCC with a Daly BMS. Do these settings look correct for my battery pack? Thanks in advance.


MakeSkyBlue SCC
WhatsApp Image 2022-06-03 at 12.38.11 AM.jpeg


Daly BMS
Screenshot_20220603-020446_SMART BMS.jpg
 
I recently updated my battery bank from Lead Acid to LiFePO4 (280Ah 8s) and I'm using a MakeSkyBlue (V118) 60A SCC with a Daly BMS. Do these settings look correct for my battery pack?

No. 26.8V will never get you anywhere near fully charged, nor will it ever get you to a consistent state of charge. Lastly, it will take longer than lead acid to charge.

MakeSkyBlue SCC

You have it set to LiPo.
You have LiFe.

Absorption: 28.0-28.8V
Float: 27.2V


Restore the defaults.
 
No. 26.8V will never get you anywhere near fully charged, nor will it ever get you to a consistent state of charge. Lastly, it will take longer than lead acid to charge.



You have it set to LiPo.
You have LiFe.

Absorption: 28.0-28.8V
Float: 27.2V



Restore the defaults.
Thanks for the reply. The controller does not allow me to set the settings as LiFe or it does not allow me to set different Absorption and Float voltages.
 
Thanks for the reply. The controller does not allow me to set the settings as LiFe or it does not allow me to set different Absorption and Float voltages.

I find it hard to believe that this charger, which you said you used with Pb, is now showing LiPo, but it won't let you change to LiFe.

If that's the case, then it needs to be replaced. It is unsuitable for use with LFP (LiFe).
 
In the controller itself, there is only one setting to choose between Pb and Li. But the app shows these other battery types also. I was wondering whether these options are available for different firmware.
 
In the controller itself, there is only one setting to choose between Pb and Li. But the app shows these other battery types also. I was wondering whether these options are available for different firmware.

Reach out to Makeskyblue and see if that's an option. If not, it should be replaced.
 
The Make Sky Blue is fine for LFP. Float and absorption are not required for LFP and that is reflected in the settings, ie disabled for LFP. Just set the max and min voltage as explained in the manual. If you insist on using float and absorption then use Pb option and set your voltages. Lots of users in the forums wirh MSB controllers.
 
The Make Sky Blue is fine for LFP. Float and absorption are not required for LFP and that is reflected in the settings, ie disabled for LFP. Just set the max and min voltage as explained in the manual. If you insist on using float and absorption then use Pb option and set your voltages. Lots of users in the forums wirh MSB controllers.

BIG qualifiers on that statement.

Absorption IS needed if you want to get to 100% SoC, to maintain balance, and it also depends on what your absorption voltage is. If you specify 3.45V/cell, you'll need a very long absorption period.

Float IS needed in a solar power system. It's the voltage floor needed to force the SCC to provide solar power for loads.

Pb is a bad idea IF temperature compensation is used.
Pb is a bad idea IF equalization is enabled.
Pb is a bad idea IF you want low temperature charging protection (assuming that's an option with MSB).
 
I have 24V so will reference that.

Why is 100% needed for balance? Once above 27.5V you can be balancing and the SCC will always aim for the upper voltage limit which for me is 28.2V. If the loads are to high then the statem voltage will always drop.

How does float set the voltage floor? All determined by power in, solar, and power out, loads. Battery is just a storage medium in the middle. More solar than loads means power can go into battery. Less means power out of the battery. It's all interconnected at the common system voltage.

MSB can handle temp for LFP, so if it's a concern then use the Lithium setting. Not an issue for me but I still use the Lithium setting so just max and min ststem voltage are set.
 
I have 24V so will reference that.

Why is 100% needed for balance? Once above 27.5V you can be balancing and the SCC will always aim for the upper voltage limit which for me is 28.2V. If the loads are to high then the statem voltage will always drop.

Some batteries will not balance below a certain voltage. Battleborn will not balance below 14.2V (28.4V).

How does float set the voltage floor? All determined by power in, solar, and power out, loads.

You left out battery voltage.

Battery is just a storage medium in the middle.

It's more than that.

More solar than loads means power can go into battery.

As dictated by what? What is telling the SCC to charge the battery if a float is not specified?

You've likely just missed the several posts by folks who follow the "LFP doesn't need float." They don't specify one, and they watch their battery voltage drop all day while the sun is out with zero solar input because nothing is telling the SCC to supply current.
 
Battery voltage tells the SCC to provide power. As an example;

Battery = 26.5V
SCC = 28V max charge setting
Solar = 500W
If there are no loads then battery will charge up to 28V using 500W.
If there are 300W of load then battery will still charge to 28V using 200W.
If there is 700W of loads then battery will discharge as it is there to make up the 200W shortfall.

What SCC allows the battery to discharge if power is available? Makes no sense. You can only charge the battery if solar is greater than loads. Whenever battery voltage is lower than SCC setting the SCC will provide charge.
 
Battery voltage tells the SCC to provide power. As an example;

Battery = 26.5V
SCC = 28V max charge setting
Solar = 500W
If there are no loads then battery will charge up to 28V using 500W.
If there are 300W of load then battery will still charge to 28V using 200W.
If there is 700W of loads then battery will discharge as it is there to make up the 200W shortfall.

What SCC allows the battery to discharge if power is available? Makes no sense. You can only charge the battery if solar is greater than loads. Whenever battery voltage is lower than SCC setting the SCC will provide charge.

I'm not sure if this is a language barrier or what, or maybe you just have experience with a single system.

The vast majority of SCC have phases of charge - bulk (constant/max current), absorption (constant/max voltage) and float (arbitrary voltage where you want to the battery to be held at or near full and the charger will provide whatever power is necessary to maintain this voltage).

In your example, once your 28V max is reached, what happens? The battery can't continue to take the 500W forever. It can only take as much as it needs to maintain the 28V, thus current will taper. THIS is called absorption. If this charger works in only this way and it keeps it pegged at the 28V regardless even if the battery can take only a tiny current, this isn't particularly healthy for batteries and goes against the charging method described by most LFP manufacturers.

Most SCC also have some absorption termination criteria where it either drops to float or stops charging. Sometimes it's based on time, a tail current or both.

To answer your one question:

A SCC that does not have an appropriate float voltage specified because that's what's telling the SCC to provide charge.
 
Float and absorption are lead acid terms, not used with lithium. Nothing wrong with holding the pack at 28V. You even stated you want to hold 100% for balance. Once sun goes down, clouds, or loads kick in then the voltage will drop. The system voltage/capacity is going up and down all the time. Generally an upward trend during the day and down overnight. Ideally it always floats between your upper and lower voltage limits without tripping anything.
 
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