How to charge my 51.2v rack batteries

[DBarr]

There are no stupid questions,
In my case only stupid people asking questions!

I have a 51.2v rack battery hooked to a solar charge controller, and in turn to a inverter that is powered by the battery.
I leave this going all the time. Powering circuits in my home and charging from the sun when it is out.
The battery rarely drops below 52v.
Questions: Do I need to disconnect the solar and discharge the battery every now and then?
Can I just leave it like it is, charging and discharging everyday?
Does it harm the battery to NOT discharge below 20% DOD?

I have read to either use 100% DOD or 80% DOD.
Just looking for some educated advise so I don't hurt my investment.

 

[rodrick]

You will not hurt the battery by only using 20% dod actually it will extend the life most likely but I do question how you figure you dod if you are going on voltage you are not getting a true dod

 

[DBarr]

You will not hurt the battery by only using 20% dod actually it will extend the life most likely but I do question how you figure you dod if you are going on voltage voltage you are not getting a true dod

You are correct, I can only guess at the DOD as I only have a way to look at voltage. My battery is always connected to solar and stays at a voltage range per chart of 70 to 80%.

 

[hwy17]

You want to get them to 100% for a few hours a week or so, if not daily. They can only internally balance themselves once they're about 95%+ charged. So hanging out in 20-80% all the time would let them go out of balance. If they go out of balance it is fixable, only causes temporary capacity loss until they get balanced again.

 

[BarracudaBob]

You want to get them to 100% for a few hours a week or so, if not daily. They can only internally balance themselves once they're about 95%+ charged. So hanging out in 20-80% all the time would let them go out of balance. If they go out of balance it is fixable, only causes temporary capacity loss until they get balanced again.

So Very true

 

[wpns]

If you provide more details on your batteries, inverter, solar charge controller, solar panels, etc, you will get a more detailed answer. But hwy17 had it right. “Installed it and it just worked fine for a long time, and then (I didn’t know it, but the batteries got out of balance, and) it stopped working right and now nothing makes any sense.” Ideally, you can talk to the BMS and check on the status of the individual cells and see how it’s doing.

 

[BarracudaBob]

I have been draining them down and bottom balance then up and getting things under control. What I am finding is a ongoing maintenance keeping the "deviants" in control. Been using all the tools and sharing a lot on other threads. I see light at the end of the tunnel. Reading and watching Wills and Andy (off grid garage) youtube's helps greatly. Having 7 packs added at different times brought on a few challenges. Setting up a bench of the side of the racks to work on the Deviants was a great help too. They will all be assimilated, resistance if wasteful.

 

[BarracudaBob]

When it gets that far out of balance and the cells are welded together you only have one choice. You have to charge each cell up to 3.65V individually. I just spent the last 3 weeks trying every suggestion out there before I popped the cover. The firmware will fight you the entire way so the main switch has to be off. Observe all safety measures and consider this your last result but the results speak for them selves.