I could really use some help getting my system parameters figured out. I am always going over voltage.

[Spoonathan]

Hello. I have already set up my first solar system and it works great most of the time. However, in the day time, my system always produces too much power and forces my inverter to go into high voltage protection and shut off. I don't know exactly where I am going wrong here. My SCC should be handling the regulation and not letting my batteries overcharge, right? Right now my BMS is having to do all the work in regards to disconnecting charging to avoid overvoltage. I have tried to change the parameters in my SCC in order to stop charging at a certain voltage, but the parameters it allows me to change are very limited and I don't think overvoltage disconnect is even an option at all. As far as my BMS goes, I've tried changing some of the parameters to stop my cell voltages from getting high enough to shut down my inverter, but I can't seem to get any of the parameters right. I feel pretty overwhelmed by the whole thing honestly. If anyone could give me advice on some of the more important parameters that may help me here or just give me general advice that would be great. Thank you.

My Specs:
PV: 6x 230w panels, one 4s group, one 2s group.
SCC: 2x Renogy Rover Series 40a, one going to each solar array group.
Batteries: 24v lithium ion, 202ah
BMS: Overkill Solar BMS, 24V model
Inverter: Giandel 3000w/6000w 24v inverter.

 

[BentleyJ]

The SCC should indeed control voltage based on the user settings. You said the Renogy Rover 40A is limited, according to the Features and Descriptions it has capability for 4 stage charging. Bulk, Absorption, Float & Equalization (for lead acid). I'm not a user of that particular brand but here is a generalized description of each stage. Bulk usually is done at constant current (0.2C for example). Absorption is done at constant voltage (28V for example which is 3.5V per cell). LFP doesn't need constant float.
Is it possible one of the cells is out of balance and reaching the BMS cut off before the other cells are charged? You may need a top balance. What are the cell voltages right at the point the BMS cuts out? This is necessary info if you want to diagnose the issue.

 

[Spoonathan]

The SCC should indeed control voltage based on the user settings. You said the Renogy Rover 40A is limited, according to the Features and Descriptions it has capability for 4 stage charging. Bulk, Absorption, Float & Equalization (for lead acid). I'm not a user of that particular brand but here is a generalized description of each stage. Bulk usually is done at constant current (0.2C for example). Absorption is done at constant voltage (28V for example which is 3.5V per cell). LFP doesn't need constant float.
Is it possible one of the cells is out of balance and reaching the BMS cut off before the other cells are charged? You may need a top balance. What are the cell voltages right at the point the BMS cuts out? This is necessary info if you want to diagnose the issue.

Thank you for the reply. The next time the bms cuts out I will try to pay attention to the voltages and get back to you. In the meantime, here is a picture of every setting I am allowed to change on my scc (at least on the app, I'm not sure if I can change more on the actual device itself.) I can change the numbers for these parameters within a window that they provide. I don't really understand what any of this means and I don't know if having two sccs going to one battery should have any influence on these values.

 

[BentleyJ]

I'm lost. The pic shows system voltage 24 but the settings appear to be for a 12V battery. You have a 24V BMS. Are each of your SCC's connected to only 4 cells?

 

[TacomaJoe]

I was getting BMS over voltage disconnect on my EPEVER so I dialed back the numbers. I have equalize and boost set at 14.2 and float set at 14.0 (mine is a 4S battery)

 

[rmaddy]

I'm lost. The pic shows system voltage 24 but the settings appear to be for a 12V battery. You have a 24V BMS. Are each of your SCC's connected to only 4 cells?

Yeah, this is really weird. Each SCC should be setup exactly the same - both for 24V. I can't understand how the screenshot shows 24V system voltage but only 12V charge settings. And how could there be over voltage if the SCC is setup to charge at only 14.4V?

Batteries: 24v lithium ion, 202ah

Post a link to the exact batteries you have.

 

[Whinny]

Get the "Renogy BT" app or the SRNE "Solar app"for your phone-you will be able to set the controller to "User" making parameters much easier to set...

Renogy DC Home app vs Renogy BT app comparisons and which to use for your Charge Controller

HI guys I wanted to compile this little bit of data in one place. When I first set up my Renogy Rover Charge controller I had a difficult time finding this and it was spread out through multiple different places so here it is: So you've just set up your new Renogy, Rich Solar, Weize, or other...

diysolarforum.com

 

[73powerstroke]

Hello. I have already set up my first solar system and it works great most of the time. However, in the day time, my system always produces too much power and forces my inverter to go into high voltage protection and shut off. I don't know exactly where I am going wrong here. My SCC should be handling the regulation and not letting my batteries overcharge, right? Right now my BMS is having to do all the work in regards to disconnecting charging to avoid overvoltage. I have tried to change the parameters in my SCC in order to stop charging at a certain voltage, but the parameters it allows me to change are very limited and I don't think overvoltage disconnect is even an option at all. As far as my BMS goes, I've tried changing some of the parameters to stop my cell voltages from getting high enough to shut down my inverter, but I can't seem to get any of the parameters right. I feel pretty overwhelmed by the whole thing honestly. If anyone could give me advice on some of the more important parameters that may help me here or just give me general advice that would be great. Thank you.

My Specs:
PV: 6x 230w panels, one 4s group, one 2s group.
SCC: 2x Renogy Rover Series 40a, one going to each solar array group.
Batteries: 24v lithium ion, 202ah
BMS: Overkill Solar BMS, 24V model
Inverter: Giandel 3000w/6000w 24v inverter.

I think that's too much for that renogy. I'm sure your exceeding their recommendations on max panel input. It's probably 520w at 12v 1040w @ 24v. Your also losing out on power when with 2 separate charge controllers you could get more power and less stress on the one cc.
You should really be running 2 cc here or move up to a 60 or 80amp . You have 1380w of solar. Prob 6 amps per panel. Either way with a mppt controller 4 panels can easily do 40amps alone.
Over paneling under charge controlling lol

 

[mikefitz]

You are using user settings, cannot use lithium default for 24volts.

Your charge volts are too high causing BMS shutdown, and a voltage surge from the controllers.

First you must revert to the protection perameters in the BMS to the default settings as delivered. The most important are high and low cell volts and pack high and low volts.

A lithium cell will charge , given time almost full , at 3.4 volts, 27.2 for a 24 volt system. I suggest setting the charge volts, boost volts, to 27.2 volts and see if the issue is solved.
If so increase the boost volts by 0.2 increments until the BMS cut off occurs. If this happend lower to the previous voltage.
There is no advantage in charging over 28.4 volts, 28 volts would be a low stress charge voltage.
Float volts should be 26.8 volts
Equalisation volts are not used for lithium, set the same as boost volts with duration at zero.
Set boost duration at 30 minutes.

Under cold conditions the 4 series array may go to a higher voltage than the charger can accept. Although specified for 100 volts, voltages over 90 volts may cause issues. You have no problem with the total watts. A 3 series array to each controller would be ideal

One last point, the voltage calibration In the Renogy chargers may not be accurate, check with meter that the volts are as expected.


Mike

 

[chess-equality]

I've read far too many not-so-good stories here about Renogy products.

It's a bummer if it advertises a high voltage cutoff and does not do it. Personally I'm never gonna allow any of the BMSes to perform the disconnect, much more so if I have a big parallel bank. It must be 2-3 layers before the BMS layer; for example SCC --> (breaker / fuse) --> inverter --> (breaker / fuse) --> BMS.

 

[Whinny]

The Renogy controller is made for them by SRNE, they also make controllers for Midnite and others....
They are a quality product

 

[Dynoman]

Hello. I have already set up my first solar system and it works great most of the time. However, in the day time, my system always produces too much power and forces my inverter to go into high voltage protection and shut off. I don't know exactly where I am going wrong here. My SCC should be handling the regulation and not letting my batteries overcharge, right? Right now my BMS is having to do all the work in regards to disconnecting charging to avoid overvoltage. I have tried to change the parameters in my SCC in order to stop charging at a certain voltage, but the parameters it allows me to change are very limited and I don't think overvoltage disconnect is even an option at all. As far as my BMS goes, I've tried changing some of the parameters to stop my cell voltages from getting high enough to shut down my inverter, but I can't seem to get any of the parameters right. I feel pretty overwhelmed by the whole thing honestly. If anyone could give me advice on some of the more important parameters that may help me here or just give me general advice that would be great. Thank you.

My Specs:
PV: 6x 230w panels, one 4s group, one 2s group.
SCC: 2x Renogy Rover Series 40a, one going to each solar array group.
Batteries: 24v lithium ion, 202ah
BMS: Overkill Solar BMS, 24V model
Inverter: Giandel 3000w/6000w 24v inverter.

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.

‎Renogy BT

‎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

Renogy BT - Apps on Google Play

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.

 

[73powerstroke]

The Renogy controller is made for them by SRNE, they also make controllers for Midnite and others....
They are a quality product

Which models?

 

[wholybee]

I was getting BMS over voltage disconnect on my EPEVER so I dialed back the numbers. I have equalize and boost set at 14.2 and float set at 14.0 (mine is a 4S battery)

STOP!

Setting the float to 14V on an LFP battery will damage it. Also, equalizing an LFP battery damage it. Equalization needs to be disabled, not sure how you do that, maybe set to 0V? Or maybe to 13.6v? and float needs to be 13.6V or less.

 

[12VoltInstalls]

The Renogy controller is made for them by SRNE, they also make controllers for Midnite and others....
They are a quality product

T
T
F? It’s debatable that renogy stuff is a decent spec imho

 

[Spoonathan]

I'm lost. The pic shows system voltage 24 but the settings appear to be for a 12V battery. You have a 24V BMS. Are each of your SCC's connected to only 4 cells?

not as far as i'm aware. I have them connected to the main busbar just like everything else. I did also notice that it has the 12v settings.

 

[Spoonathan]

Yeah, this is really weird. Each SCC should be setup exactly the same - both for 24V. I can't understand how the screenshot shows 24V system voltage but only 12V charge settings. And how could there be over voltage if the SCC is setup to charge at only 14.4V?


Post a link to the exact batteries you have.

560.9US $ 29% OFF|Grade A 4pcs 2021 New 3.2v 200ah Lifepo4 Battery With Qr Code Lfp Lithium Solar 12v 24v 202ah Cells Not 280ah Ev Marine Rv Golf - Rechargeable Batteries - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[Spoonathan]

.

 

[Spoonathan]

I think that's too much for that renogy. I'm sure your exceeding their recommendations on max panel input. It's probably 520w at 12v 1040w @ 24v. Your also losing out on power when with 2 separate charge controllers you could get more power and less stress on the one cc.
You should really be running 2 cc here or move up to a 60 or 80amp . You have 1380w of solar. Prob 6 amps per panel. Either way with a mppt controller 4 panels can easily do 40amps alone.
Over paneling under charge controlling lol

Thanks for your reply! I'm not sure if you were aware, but I do indeed have two CCs. I have 4 panels connected to one and 2 connected to the other. You did make me think about something. I was under the impression when I bought the CC that it had a max voltage of 150v. I now realize that It's max is only 100v. My panels have a max voltage of about 30v which means that I am absolutely exceeding that on the one controller. Is there a way that I can connect my panels in two series groups of 3 panels going to each CC? I'm not sure if you can do odd numbers of panels in your array. I thought it had to be in even groups.

 

[Spoonathan]

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.

‎Renogy BT

‎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

Renogy BT - Apps on Google Play

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.

Thanks for your reply! Very informative. it's nice to hear from someone who has my specific model. Just to clarify, the settings you provided are for a 24v system, correct?