Is it ok to add new Lithium batteries to an older Lithium install ?
asked
mixing battery ages
What is the difference in age?
Was the original battery bank cycled every day?
And how deeply discharged?
At some point ( years? ) the answer is ...
Do not add a new battery, to a very old battery bank.
Verify that the two batteries have the same voltage before connecting in parallel.
Thank you for coming back on this, I asked a very broad question, in actual fact what I am trying to ascertain is can I build my Lithium battery bank in stages, this install is for a cruising yacht. So currently (pardon the pun) I am converting from fully AGM to Lithium for the "consumer" load, fridge freezer nav' day to day house hold load. Not spending along time away from shore power at the moment but as time away increases more autonomy will be required.
Bottom line is can I get away with a couple of thousand euros/pounds/dollars now and a couple later and maybe more later. Or do I have to commit to the full battery install now so they are all the same age, as you would AGM.
Depends on what brand you are planning to use. At least they must have internal BMS and even your supplier gives permit to connect different ages together they will have different internal resistance. That is issue as old cells will have higher resistance so new cells will need to handle more current as not divided evenly. That is okay as long as you do not exceed charge and discharge ratings of your battery. Brand and model should any case be same or you can have differences in chemistries and BMS which can lead to problems.
In general many suppliers state that you can add more batteries to same group like in example pylon tech which have guide how to connect different versions together. Some suppliers say that no more than 6months with daily cycled max 50% etc. So like other answered to you it depends how you use your system. I suggest that you present your planned usage to reseller and they will make sure that warranty will not been affected due mixing batteries with different age.
I would not be too concerned.
Our motorhome 4 cell Sinopoly 300Ah LiFePO4 battery has survived 9 years of full-time travel with just a 5% capacity loss.
About a month ago I added a new 4 cell EVE 280Ah LiFePO4 battery in parallel.
I will leave it to the theoretical experts to inform us all which bank will die first.
I expect not having to report back for another 9 years.
