@fhorst ,
You are trying an experiment by mixing cells of different capacity.
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I would also suggest you start a new thread so this experiment can be easier for others to find with search engines. That way it will help others.
Yes, that will be a good idea.
I already made a thread discussing the usage of different ah cells, "mix n match" and from it it became clear it is normal practice to do so.
Calling it "experiment" would suggest I'm doing something totally different then standard.
It's not.
Even adding new cells in parallel to old pack to boost the life is common practice!!
As lifepo4 doesn't drain other cells like Lead acid does, you can have "bad cells" mixed up with good ones!!
A "bad" old cell just doesn't have the same capacity, and for longer period of time it can have more difficulties to hold the charge.
Bad lead acid takes twice or more the amount of energy to charge, (normally 75% efficient, bad LA 50% or worse) can do about 20% of original capacity, and loses this fast (can't hold on for a few hours)
This already makes huge difference in usage.
Bad lifepo4 still is +95% efficient, can hold about 75% (or less) of original capacity, and holds it just fine for a couple of days.
In solar, daily charge and discharge, the low efficiency of LA is already bad with good battery, with bad ones...
Sad.
Holding on to this charge for just a few hours (less then 12) is the next problem.
After dawn, there are more hours without sunlight.
The only thing for Lifepo4 in daily charge / discharge is its lower capacity.
Adding new cells to overcome this limitation is used a lot, for many, many years not a problem and not experimental.
Adding lifepo4 to a bad lead acid setup, that would be experimental
When my cells arrive ( order will be finished in a few days) I'll make a new thread.
A few % difference in SOC is for me not a problem.
Balancing them by placing in parallel will balance just fine for my solar application.
1 or 2% difference in SOC will happen standard by just using them.
Even after official by the book top or bottom balance, after a few weeks or months.
It's just the nature of lifepo4.
They will go / be out of balance.
This is why
@Will Prowse and others suggest to Balance every few months or once a year, depending on your usage.
Higher C rates will give greater imbalance.
(Did) Charging at C0.33 or C0.1 makes huge difference.( For me 230 or 70A)
Normally it will be mostly C.01 for most people, including me.
During rain season, I'm charging fast, as there are just a few hours of open sky/ full sunlight a day.
My solar panels are matched for those days.
Probably I need to balance twice a year, before and after rain season.
Having a few % imbalance in the cells and parallel sets is normal!
Naturally, when my new cells arrive, I will add them at the moment both cells have the same voltage, with the new cells as reference.
(Probably 3.29/3.30v)
After this top charge to 95 - 100%
And this twice a year to Balance the cells.
OT...
I wonder how battleborn does this, as their cells go max to 85%.
Maybe they just accept the imbalance?
