Mixing new and old lithium LiFePo4 batteries

Hello everyone.
I wanted to know if anyone had experience or knowledge in regards mixing new and old lithium ion LiFePo4 batteries. I am considering an installation with 1 battery module from Pylontech or BYD (around 2.5 kWh) with the possibility of upgrading the system within a few years with more modules.
I remembered that with lead acid mixing new and old was not a good idea, and I wondered if this would also be the case for lithium ion. Would it depend on the inverter / charger? Would some sort of balancing be required before installing the new module having used the old module already for a few years?
Thanks in advance!
I wanted to know if anyone had experience or knowledge in regards mixing new and old lithium ion LiFePo4 batteries. I am considering an installation with 1 battery module from Pylontech or BYD (around 2.5 kWh) with the possibility of upgrading the system within a few years with more modules.
I remembered that with lead acid mixing new and old was not a good idea, and I wondered if this would also be the case for lithium ion. Would it depend on the inverter / charger? Would some sort of balancing be required before installing the new module having used the old module already for a few years?
Thanks in advance!
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Comments
Experience on this forum has shown that there is very little lose of capacity at 3 to 5 years so combining old and new should not be an issue in that time frame. For battery modules, it's necessary to make sure they are fully charged before installing in series/parallel connections. It is helpful to have access to individual module cells for monitoring during charging.
Rick
Yes, it is important to verify that all the cells in a module are achieving top balance, both initially and periodically while charging.
Rick
With Lithium Ion batteries the coulomb/current charge efficiency of around 99% does not change much as they age and they do not need any absorb time.
The one thing that LFP batteries do loose with time is capacity, if used conservatively I would say that this would be around 1%-2% per annum.
Both the Pylontech and BYD "modules" have an inbuilt BMS which if wired up to external equipment as per the manufacturers instructions should protect the battery against any imbalance issues. I would ask Pylontech and BYD for their advice about adding new modules at a later date. I can't see why there would be any problem doing this.
Simon
32x90Ah Winston cells 4p8s (24V), 4kW Latronics Inverter, 1160W of Solar Panels, homemade MPPT controller
Homemade BMS https://github.com/simat/BatteryMonitor
I don't think it would be good to mix internal to a bank different age batteries unless the BMS was designed for it.
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