Note: The following is for Lithium Iron Phosphate (LiFePO4) batteries. If you have Lithium Ion batteries your settings will be different, but this will give you an idea of how I use the Renogy Rover 40 amp SCC.
The Renogy Rover 40 only has settings for 12 volt systems. For 24 volt systems double the values to get the actual settings. Example for a 28 volt boost setting set the controller for 14 volt boost.
The LI settings of the Renogy Rover 40 amp SCC will tend to overcharge a Lifepo4 battery. At the14.4v boost setting (28.8 volts for 24 volt systems) LiFePO4 are in a very high charge state. Above 29.2 volts there is risk of damage to the battery. If the Rover-40 truly stopped charging at 28.8 volts it may be OK, but I find the Rover-40 can be off by 0.1 or 0.2 volts or more and this is common with this solar charge controller. Also, at 28.8 volts you are at high risk of the BMS in your battery going into overvoltage shutdown which can cause problems.
Your BMS in your battery will (or should) shut down your battery before any damage to the cells with overvoltage or undervoltage protection, but you don't want to use this feature to run your solar system since it is a failsafe. You need to program the Rover-40 Boost Voltage to a voltage below your BMS overvoltage and you need to remove your loads before the battery BMS goes into undervoltage or make sure the battery voltage never gets that low (this can be done with an automatic transfer switch when using an inverter/grid power).
Min voltage for LiFePO4 Cells is usually 2.5v or 8x 2.5 = 20 Volts and Max voltage for LiFePO4 Cells is usually 3.65v or 8x 3.65 = 29.2 Volts
Your BMS may cut out before the Min or Max Voltage depending on how it is programmed, but you don't want to exceed the Min or Max and really keep a buffer above the min and below the max.
So, with the Rover-40 set to 28.8v (I think this is the (LI) Lithium Ion settings) and a voltage error of 0.2 you can get to 29.0 (or more) and damage your battery or your BMS will kick in to save your battery and shut things down.
The Rover-40 is not a precise SCC, but given its price point and the BT and ability to program and monitor on your phone it is a good value for entry/small solar systems. After some time (going on my 3rd year) I have learned to use it well. Just have to know its limitations...
I use the Renogy BT-1 Bluetooth Module that plugs in the Rover-40 Rs232 port.
www.amazon.com/Renogy-Bluetooth-Module-Communication-Controllers/dp/B0894SDTSL
With that Module I use the Renogy BT App loaded on my phone to program the settings and monitor the Rover-40 and is free. The app allows many parameters to be set in USR battery setting. See the attached manual.
APP for solar charge controller operation in smart PV power system. It's for solar charge controller working parameter setting and reading. All data can be displayed in a diagram. Meet the Renogy BT. a convenient way to manage and monitor your solar power system all in the palm of your hand...
apps.apple.com
a convenient way to manage and monitor your solar power system
play.google.com
I am using the the following USR settings. The Rover LI settings are to aggressive for Lifepo4 Batteries.
Set to USR & set:
High Voltage Disconnect 14.5v
Charge Limit Voltage14.1v
Equalization Charge Voltage 14.0v
Boost Charge Voltage 14.0v (also called Absorption)
Float Charge Volt 13.6v
Boost Char Return Volt 13.3v
Over Disc Return Volt 11.0v
Low voltage Alarm 10.9v
Over Discharge Volt 10.5v
Discharge Limit Volt 10v
Over Disc Delay Time 5s
Equalization Charge Time 0 Min
Boost Time 10 Min
Equalize Charge Interval 185 (Note this value cannot be 0 because controller will get stuck in boost mode)
Temp Comp 0A
Unplug temp sensor from the Renogy-40 amp Solar Charge Controller. It is used for lead acid batteries.
These settings should get you started. You can adjust from there.