Issues with Renogy PG 40A MPPT Controller

Ethan_AZ

New Member
Current Solar System The Classic 400W: 2200W Giandel Pure Sine Wave Inverter, two BattleBorn LiFePO4 100Ah batteries, Renogy PG series 40A MPPT charge controller.

After closely following Will's instruction per the website blueprint and the book I have had some recurring issues with this system typically related to over-discharge. There have been a few instances of over-discharge: the inverter sounds the alarm and the charge controller reads E1 error for over-discharge. So far, this had seem related to cloudy days or somewhat (not much) more electronic usage, but I have been unable to properly diagnose what is going on. The most current issue has resulted in a small crisis at our off-grid establishment: over-discharge alarm has gone off and the charge controller appears to have no power and no display. The fuses and breaker are intact and did not trip. the controller is currently disconnected completely and system is off to safeguard components.

I am a beginner and my understanding of the systems workings in detail is definitely lacking. I am left somewhat baffled by the problems as the battery monitor (in the placement indicated in the book) shows us having 45kWh. Our hunch right now is that some settings need to be adjusted on the controller to allow this system to function properly, but on a basic level the settings were 12v set to Li. Please help! This forum is likely to be much more helpful and direct than other sources. Thank you.
 

snoobler

Solar Honey Badger
Moderator
If you are completely discharging your batteries, which you should try to avoid, what you describe sounds normal.

What is the battery voltage when this occurs?

I suspect you're tripping the battery low voltage protection and the BMS is preventing further discharge of the battery thus de-powering the Renogy as it requires a live battery for power.
 

Bob142

Build more, learn more.
Hi Ethan, welcome to the forum.

First thing that jumps out at me: the two 100Ah Battle Born batteries have a capacity of roughly 2,560Wh (100Ah x 12.8V x 2). You state that your battery monitor shows 45kWh (45,000Wh). That's not possible. Either that's a typo in your post, or it's definitely not set up correctly to monitor your battery state of charge (SoC).
 

Ethan_AZ

New Member
If you are completely discharging your batteries, which you should try to avoid, what you describe sounds normal.

What is the battery voltage when this occurs?

I suspect you're tripping the battery low voltage protection and the BMS is preventing further discharge of the battery thus de-powering the Renogy as it requires a live battery for power.

Hey Snoobler,

The battery voltage has been pretty consistently reading 12.7 or right around there, but the system is currently off and I am actually out on a work trip. I suppose I should be checking it every day but I am gone about half the time. Sometimes I have seen it go up to 13.1, and I do not know if this is an issue. Thanks for the feedback and insight!
 

Ethan_AZ

New Member
Hi Ethan, welcome to the forum.

First thing that jumps out at me: the two 100Ah Battle Born batteries have a capacity of roughly 2,560Wh (100Ah x 12.8V x 2). You state that your battery monitor shows 45kWh (45,000Wh). That's not possible. Either that's a typo in your post, or it's definitely not set up correctly to monitor your battery state of charge (SoC).
Hi Bob, thanks for the welcome.

Oh boy, well its certainly sounds like something is off. This is not a typo, but the actual display. I felt explicit instructions on battery monitor installation were somewhat lacking in Will's material (perhaps just to generally cover all system types, Will is great!) and I referred to a diagram (from Bayite, the monitor brand) and a couple youtube videos to help me out.

71vyuArVdSL._SL1500_.jpg

I connected the monitor in configuration #2, not right? Thank you so much for the info and help.
 

snoobler

Solar Honey Badger
Moderator
12.7 is a very low state of charge.

1605848748415.png

Your batteries aren't being charged enough. You keep running them to empty and then partially charging them only to use them up again.
 

jony101

New Member
On the battleborns, the full voltage is 14.4 volts, you need to measure this voltage at the battery terminals. More then likely you have "voltage drop" from the controller to the battery. (example the controller might read 14.4 volts but your battery terminals only read 13.8 volts) . Next time in full sunlight measure the voltages between the 2. Also verify the voltage between the bayite meter your using and the battery terminals, just to make sure they are accurate. Use a multimeter is preferable at the battery terminals.
If you have voltage drop the setting for "lithium" on the controller will be wrong, your going have to into the "manual" setting and increase the bulk voltage setting. If you have .5 volt difference, instead of 14.4 volts, you need set bulk voltage to 14.9 volts, then measure the voltage at the terminals to see if it climbs to 14.4 volts.
The battleborn has built-in bms so higher voltage won't damage them, lifepo4 can actually go up to 14.6 volts (3.65v per cell). Depending on the size of your panels it might take several days or weeks to fully charge 200ah of lifepo4.
 

snoobler

Solar Honey Badger
Moderator
@Ethan_AZ,

Please ignore jony101's advice to change your charge controller numbers for the reasons given. He is giving you bad advice due to his lack of understanding and based on his limited experience with his own system and its deficiencies.

Checking for a voltage difference isn't a bad idea, but it's not likely the issue. Your 400W panels will take more than one day to fully charge your batteries assuming you use NO power and your panels are perfectly oriented and tilted.

You are likely frequently using more power than you can replenish in a day's worth of charging, and you're consistently behind the curve - never getting the battery fully charged.
 

jony101

New Member
Check for voltage drop, if it checks good then do what snoobler says. Otherwise you will at most get your battery to 80 percent slowly. If you want to fast charge your battery with solar, your charge voltage has to be high enough to do it. With voltage drop, you at most will be trickle charging your battery, no matter how much sun you have. According to your description the voltage of the battery has only gone up to 13.1 volts, thats too low, to fully charge it has to be at 14.4 volts and stay there for a while. The 14.4 volts you have to measure at the terminals, otherwise you will be relying that the charge controller has the accurate voltage.
You already have your controller set to lithium, without voltage drop and good sun, your battery should be at 100 percent. It might take a while but it will get to 100 percent. My 220ah lifepo4 at 50 percent took 2 weeks to get back to 100 percent in the summer with good sun from a 240 watt panel.
When you have full sunlight what is the max amps you see going into your battery? On my 240 watt panel in winter, I see a max of 9 amps, if you have 400 watts, you should see more then 9 amps.
 
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