MPPT User Settings for LiFePO4 Battery.

[tboaks]

New member here, please forgive me if this has been covered before.
I have replaced my AGM battery with a 200AHr LiFePO4 from Renogy.
My MPPT Charge Controller is a 40A Renogy Commander which has no LiFePO4 Charge Settings,
but does have "User Settings" for charging parameters.
Renogy Tech Support has been useless, as all they can do is read from their manual.
The Renogy Battery manual gives me the following Charge Parameter settings as follows:
"Charge/Boost = 14.4V"
"Bulk/Absorbtion = 14.4V"
"Boost Return = 13.2V"
"Over voltage Disconnect = 15V"
"Over voltage Reconnect = 14.2V"
"Low Voltage Reconnect = 12.6V"
"Under voltage Warning = 12.0V"
"Under voltage Shutdown = 10V"
The Charge Controller "User Settings" not mentioned in the batter manual are:
"Boost Time", "Low Voltage Disconnect", "Discharge Limit", "Float Charge" and "Charge Limit"
Can anyone help me with the values for the above User Settings? (TIA)

 

[Samsonite801]

Here's a good goto article I like to keep at arm's length.. This is for people who are going for the max battery life / cycles.

Best LifePo4 charge controller settings known to man for Maximum Service life and Minimum battery stress!!! 5,000-10,000+ cycles?

---ORIGINAL TITLE---- Best charge controller settings to achieve 10%-90% usage on lifepo4 ? EDIT-UPDATE and the ANSWER to this question. . . This post is a accumulation of all the great and wonderful information given to me by all the great people on this thread. I consolidated all of this...

diysolarforum.com

Below are some good baseline settings if looking for max safe voltages to get most SoC, not being super paranoid about getting the most cycles possible (the way I see it, it's like 'normal' safe thresholds for expected typical lifespan)..

Recommended Charge Profile for DIY LiFePO4 Batteries *Sticky Post*

12V 4S LiFePO4 Battery w/ BMS: Absorption: 14.5V Float: 13.6V Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc) 24V 8S LiFePO4 Battery w/ BMS Absorption: 29V Float: 27.2V Inverter Cut-off: 21.4V-24V 48V 16S LiFePO4 Battery w/ BMS Absorption: 58V Float: 54.4V...

diysolarforum.com

When those posts talk about 'cell' voltage, you can multiply by 4, to get the 12v module equivalents...

Bulk is usually considered the highest current charge mode which is CC (Constant Current), where current is kept at max level, voltage is allowed to rise, until it reaches Absorption voltage trigger, then charger flips to Absorption mode which is CV (Constant Voltage), where the voltage is regulated at that set-point, allowing the current to taper off until current gets to some low point (sometimes on a timer).

Then at some point the charger flips to float mode which LFP batteries don't need (lead acid require float for maintenance since they self discharge more), LFP have very little self discharge, so usually once we are ready to flip to float mode, we just either shut off the charger, or set float low enough that the current basically stops (charging stops). But high enough for the solar charger to kick in and supply the inverter loads when they ramp-up again without the battery discharging below that.

On your Renogy, I'm not sure what they mean by 'Charge/Boost', you might need to read up more on what they call the difference between Bulk (CC), and 'Charge/Boost' in their charge profile... Perhaps Bulk in this case is one max amperage point, and Charge/Boost is a higher max amperage CC mode?

I might just start by keeping Charge/Boost and Bulk/Absorption at same level, until I figured out what is the difference between them.

 

[Samsonite801]

I just took this clip out of the Renogy manual, these are their definitions of the stages...

What they refer to as Constant Charging stage is just really just like the typical Absorption Stage, a CV mode (with Boost being a mode within Constant Charging mode, so still CV I guess).

Bulk (CC) means the charger is working as hard as it can utilizing MPPT algorithm to get max battery charging amps, where with Absorption (CV) the amps are tapering off, so it doesn't need to utilize MPPT efficiency algorithm, it will just load down the panel array up to a point to meet the required Absorption voltage on the battery charger stage.

 

[mikefitz]

Boost and absorbtion volts are the same thing, just odd terminology used by Renogy. Regard boost ( absorbtion) voltage as the 'target' charge voltage. When the charger wakes up in the morning it puts as much energy into the battery from the panels as it can, until the voltage on the battery reaches the 'target' boost volts . This period is termed the bulk stage, the battery is almost fully charged in this period. The charger then holds the voltage constant for the absorbtion period, the boost duration. For a lithium battery ( with well-balanced cells) this can be short, 30 minutes. Once the absorbtion period is completed the charger will enter the float stage with a voltage lower than the absorbtion volts. For lithium this will help power any load during the daytime( from solar) whilst keeping the battery fully charged.
Your settings, assuming you are in user mode
Boost volts 14.2
Boost duration 30 min
Float volts 13.5
Boost reconnect 13.3
Temperature compensation disabled
The above are the important settings that determine how the battery is charged.
Equilisation volts 14.2
Equalisation duration 10 min
Equalisation volts are only used with flooded lead acid batteries. Since this mode cannot be disabled, set to values that won't cause issues.

Overvolts disconnect 14.6
Overvolts reconnect 14.4
This is to prevent OverVoltage situation if the controller has a brain fart.

The low voltage and warnings settings are for the load outputs and don't relate to charging.

 

[tboaks]

Here's a good goto article I like to keep at arm's length.. This is for people who are going for the max battery life / cycles.

Best LifePo4 charge controller settings known to man for Maximum Service life and Minimum battery stress!!! 5,000-10,000+ cycles?

---ORIGINAL TITLE---- Best charge controller settings to achieve 10%-90% usage on lifepo4 ? EDIT-UPDATE and the ANSWER to this question. . . This post is a accumulation of all the great and wonderful information given to me by all the great people on this thread. I consolidated all of this...

diysolarforum.com

Below are some good baseline settings if looking for max safe voltages to get most SoC, not being super paranoid about getting the most cycles possible (the way I see it, it's like 'normal' safe thresholds for expected typical lifespan)..

Recommended Charge Profile for DIY LiFePO4 Batteries *Sticky Post*

12V 4S LiFePO4 Battery w/ BMS: Absorption: 14.5V Float: 13.6V Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc) 24V 8S LiFePO4 Battery w/ BMS Absorption: 29V Float: 27.2V Inverter Cut-off: 21.4V-24V 48V 16S LiFePO4 Battery w/ BMS Absorption: 58V Float: 54.4V...

diysolarforum.com

When those posts talk about 'cell' voltage, you can multiply by 4, to get the 12v module equivalents...

Bulk is usually considered the highest current charge mode which is CC (Constant Current), where current is kept at max level, voltage is allowed to rise, until it reaches Absorption voltage trigger, then charger flips to Absorption mode which is CV (Constant Voltage), where the voltage is regulated at that set-point, allowing the current to taper off until current gets to some low point (sometimes on a timer).

Then at some point the charger flips to float mode which LFP batteries don't need (lead acid require float for maintenance since they self discharge more), LFP have very little self discharge, so usually once we are ready to flip to float mode, we just either shut off the charger, or set float low enough that the current basically stops (charging stops). But high enough for the solar charger to kick in and supply the inverter loads when they ramp-up again without the battery discharging below that.

On your Renogy, I'm not sure what they mean by 'Charge/Boost', you might need to read up more on what they call the difference between Bulk (CC), and 'Charge/Boost' in their charge profile... Perhaps Bulk in this case is one max amperage point, and Charge/Boost is a higher max amperage CC mode?

I might just start by keeping Charge/Boost and Bulk/Absorption at same level, until I figured out what is the difference between them.

Thanks for both of those articles, they help me better understand the whole process. And it was good for me to see the Will Prowse article, I have always thought his info was very good and didn't realize that he is the Forum Owner.