LV6548 Battery Charging

[Ozark]

Hi all, my system is installed in a travel trailer. Pretty simple, panels, 6548, 2 EG4 batteries. –no mains AC
Everything works great except I can't get a charge to the batteries.
The batteries are connected because the inverter draws from them.
I don't have BMS communication because of the typical comm problem, I've tried user and lithium settings
The PV string input shows up fine, just no output to the batts.

Sorry to be such a dolt, could someone give me the quick rundown of appropriate settings?
–I think I have all the timers off-

 

[Watts Happening]

I have to imagine the first place to start would be the battery charge voltage is lower than the current state of charge. IE your batteries are at 58v but inverter is set to only charge to 57v.

 

[Ozark]

Thanks for the reply Watts,
my batts are almost flatlined now, 49.9v or so

 

[Watts Happening]

Thanks for the reply Watts,
my batts are almost flatlined now, 49.9v or so

Sure, but if your settings are at 49v or something to that effect, you'd be in the same situation. Just a thought.

 

[Ozark]

Sure, but if your settings are at 49v or something to that effect, you'd be in the same situation. Just a thought.

Gotcha! Thoughts are what I need.
I'll check the kick-in voltage if I can find
Thanks again

 

[Ozark]

This is the control without inverter running. Panels are in shade but display is the same (0 output) when the panels are making 900w.
Note also the battery voltage scale, it reads as if it is charging i.e. it flashes like a t-bird turn signal sequentially from left to right (here it happens to be at the point all segments are lit)

 

[Skypower]

What is the voltage output to the MPP of your panels

 

[Ozark]

They are 24v panels (37.5Vmp), 3s/2p so 150v 75v
Right now at 0a it is 120v

 

[Ozark]

They are 24v panels (37.5Vmp), 3s/2p so 150v 75v
Right now at 0a it is 120v

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2 strings of 3

 

[Skypower]

That MPP just isn’t happy until it gets to around 125 volts. You can wake it up by putting all six in series for 225 volts. Yes I know it says 90 starting but……

Edit! Stop! Over voltage! My bad! The maximum you can put in series is 5 panels.

 

[Skypower]

Respect that PV voltage! It will literally kill you in a heartbeat if you complete a circuit across your chest! Make sure your breakers are in excess of the voltage and DC rated and tighten the screws a few times later as the strands settle down especially in a mobile application.

 

[Ozark]

yeah that's skerry!
I was just checking the breaker, LOL. it's15a @ 400v DC
I could just add a panel at a time to screw up my courage as I watch the output for signs of life.
But I can't see any settings that are off...

 

[Skypower]

yeah that's skerry!
I was just checking the breaker, LOL. it's15a @ 400v DC
I could just add a panel at a time to screw up my courage as I watch the output for signs of life.
But I can't see any settings that are off...

Look back at my post! Don’t put all six in series if your maximum ocv is 250

 

[Ozark]

Good, I was just going to say I thought the 6548 is max 250v

 

[Skypower]

Glad I caught ya. Ok at least I know which version of 6548 you have, the most common. I miss took your panel power point for OCV. You can run 5 in series and you should see power generation.

 

[Ozark]

Thanks, I'll pay attention to the voltage when the sun comes out and re-string up to 5 to see if that helps
Better than trying to decipher the setup menu!

 

[Skypower]

I don’t know how cold it gets where you are but panels can make more voltage when it gets cold and could put you over the top in winter. So you may need calculate if you need to reconfigure later. 237 Volts does give you some head room. But enjoy the juice now.

 

[Lt.Dan]

Good, I was just going to say I thought the 6548 is max 250v

The MPP Solar and other models are 250v. The EG4 model is 500v. Which model do you have?

 

[Skypower]

And now there are a lot of MPP 6548V versions showing up. The (V) denoting 390 max OCV. Just to make it more confusing. So now the same box shape with different paint schemes can have 250, 390 and 500 max OCV.

 

[Ozark]

Mine is an MPP, I think the second wave from over a year ago - or was it too?. At the time I was worried about supply chains, etc. but I wish I had waited for version 2.0 or 3.0, especially with the higher voltage limit. The low limit makes it hard to get panels to fit efficiently.