Help with Inverter and BMS settings

[fopoku2k2]

So I read that the inverter and BMS voltage settings are supposed to be different. I need helping confirming if my settings are right since I have been getting voltage spikes in the morning after the sun has charged the battery bank for a few hours. I am using the following:

1. 16x 3.2v 280Ah CATL Cells
2. 48v 200A Smart Daly BMS and
3. Growatt SPF 5000 ES

INVERTER SETTINGS

1. Bulk Charging = 55.0v
2. Float = 54.0v
3. Low DC cut-off = 46.0v

BMS SETTINGS

1. Volt High Protect = 59.0v
2. Voltage Low Protect = 48.0v
3. Balance Open Start Voltage = 3.28v

Thanks for reading and any advice would be greatly appreciated

 

[FilterGuy]

LiFePO4 Voltage Settings guide for BMS, Chargers and Loads

To get the document, click on the orange button at the top of the page. All the voltage settings in the BMS, Loads and Chargers can be daunting to figure out. This paper attempts to explain the various settings, how they relate to each other...

diysolarforum.com

 

[NVS]

You should watch these videos for more insight.

 

[Scph9002]

Default lifepo4 settings in your equipment are a good start.
Daly bms default max and min voltage limits (2.2v-3.75v per cell) are usually higher and lower than charge controllers limits (2.7v-3.65v per cell) which is good because you want the charge controller to handle the stopping of current which it is built for it unlike a bms.

Links to documents and videos above from other users are great if you want to finetune your setup for longliveity.

If you ask me I say best well rounded settings would be:
Charge controller
Bulk: 3.525v
Float: 3.4v
Rebulk 3.3v
Low voltage disconnect: 2.7v

BMS
High cell voltage: 3.65v
Low cell voltage: 2.5v

 

[molnar252]

hello, I want to ask, I have lifepo4 batteries 48V system, I want to use 70%-80% of the battery capacity for the best settings. how to set the inverter and BMS voltage?

 

[Scph9002]

hello, I want to ask, I have lifepo4 batteries 48V system, I want to use 70%-80% of the battery capacity for the best settings. how to set the inverter and BMS voltage?

Trying to charge to 70-80 and even up to 90% is highly impractical. Lifepo4 16 cell at 70% soc would be around 53v (maybe) but would you set your inverter (assuming your inverter is a charge controller/inverter hybrid) to charge to 53v It would reach terminal voltage of 53v long before it is at 70% capacity and start to slow down charging taking ages to reach 70% soc or a rested internal voltage of 53v.

There is software that can do coulomb counting, basically do a good estimate of current soc based on charge/discharged amps over time but the calculated soc will drift after a few cycles to the point you are nowhere near 70% mark, it will have to charge to at least around 3.5v (near 100%) per cell to recalibrate its soc.

Long story short: It will take way to long time to charge to 70%. Check out the stickies above and use the recommended "5000 cycles" charge profile

 

[FilterGuy]

Trying to charge to 70-80 and even up to 90% is highly impractical. Lifepo4 16 cell at 70% soc would be around 53v (maybe) but would you set your inverter (assuming your inverter is a charge controller/inverter hybrid) to charge to 53v It would reach terminal voltage of 53v long before it is at 70% capacity and start to slow down charging taking ages to reach 70% soc.

There is software that can do coulomb counting, basically do a good estimate of current soc based on charge/discharged amps over time but the calculated soc will drift after a few cycles to the point you are nowhere near 70% mark, it will have to charge to at least around 3.5v (near 100%) per cell to recalibrate its soc.

Long story short: It will take way to long time to charge to 70%. Check out the stickies above and use the recommended "5000 cycles" charge profile

If the system has Closed loop communications between the battery and inverter, you might be able to use SOC instead of voltage to determine when to stop charging. It all depends on what settings are available in the inverter, but it should be possible to charge quickly to 70% and then stop. However, the SOC is calculated by the batteries, so without the closed loop, this would not be possible.

 

[molnar252]

If the system has Closed loop communications between the battery and inverter, you might be able to use SOC instead of voltage to determine when to stop charging. It all depends on what settings are available in the inverter, but it should be possible to charge quickly to 70% and then stop. However, the SOC is calculated by the batteries, so without the closed loop, this would not be possible.

Trying to charge to 70-80 and even up to 90% is highly impractical. Lifepo4 16 cell at 70% soc would be around 53v (maybe) but would you set your inverter (assuming your inverter is a charge controller/inverter hybrid) to charge to 53v It would reach terminal voltage of 53v long before it is at 70% capacity and start to slow down charging taking ages to reach 70% soc or a rested internal voltage of 53v.

There is software that can do coulomb counting, basically do a good estimate of current soc based on charge/discharged amps over time but the calculated soc will drift after a few cycles to the point you are nowhere near 70% mark, it will have to charge to at least around 3.5v (near 100%) per cell to recalibrate its soc.

Long story short: It will take way to long time to charge to 70%. Check out the stickies above and use the recommended "5000 cycles" charge profile

this data of yours is using approximately what % of battery capacity?
If you ask me I say best well rounded settings would be:
Charge controller
Bulk: 3.525v
Float: 3.4v
Rebulk 3.3v
Low voltage disconnect: 2.7v

BMS
High cell voltage: 3.65v
Low cell voltage: 2.5v

 

[Scph9002]

this data of yours is using approximately what % of battery capacity?
If you ask me I say best well rounded settings would be:
Charge controller
Bulk: 3.525v
Float: 3.4v
Rebulk 3.3v
Low voltage disconnect: 2.7v

BMS
High cell voltage: 3.65v
Low cell voltage: 2.5v

99%