Terminology Fix. !
Battery = Pack: A Pack is a set of cells assembled into a complete battery with a BMS and is a complete stand-alone entity.
Bank : A Collection of 2 or more Complete Batteries working cooperatively.
A Bank can be a combination of Batteries in Parallel _or_ Batteries set in Series to increase Voltage with Each Series Paralled into the Bank.
48V takes 16 Cells to form a Battery with the BMS to manage "that" individual Battery Pack. *Series is generally NOT Advisable, that is essentially a remnant of FLA Lead Tech which is Brute Force Tech compared to ANY Lithium based system. Imagine 16x6V Lead @ 135Lbs of lead each just to make ONE 48V "Bank"... The days of teh DoDo ! BTW: I came from an FLA Setup.
Most BMS' which are FET Based are extremely limited when it comes to Series Connections. If you have 4 12V Packs in Series to get to 48V, each BMS needs to be capable of handling the voltage changes should one or more packs fail within that series. Quite often that can melt down the FETS.
BMS' which depend on Realy's have no issues with FETS as the Relays do the switching on/off and as such isolates each BMS and the pack while the remaining relays "take the hit" (simplke terms).
I run a Larger Bank (5 packs - 1190AH/30kWh) which is all 24V/8S (no paralleled cells in packs). This has run with Relay Based BMS and zero issues as the build/wiring etc is all properly equalized. ( Same length of wires, same config across). I am now switching to all JKBMS at Great Expense and packs are IN PARALLEL and there are no issues as yet. In fact the performance of the online packs has improved quite a bit. Also within 1 hour of entering "Float Mode" all cells across everything average a Mean Delta of 0.005mv difference which is exceptional. It is a Lovely Sight to see !
Sadly there is a LOT of TWaddle coming from other tech like FLA which includes wives tales & more that get dropped all over Lithium Based system. What is worse is that not all Lithium Tech is the same, like Li-Ion (NMC, NCA etc) versus LFP (Lithium Iron Phosphate / LiFePO4) such as the "keep the charge level between 20-80%" which does NOT Apply to LFP ! but the echo chamber keeps that twaddle flying.
A SPECIAL NOTE ABOUT CELLS IN PARALLEL !
Many people are doing this and it comes from the other Lithium Bases, because they look at an EV which all run Paralell & series within their packs.. These are VERY Different animals. EV's also use Perfectly Matched Batched & Balanced cells which of course are PREMIUM ! Regardless of the particular sub-chemistry including LFP. Properly Matched & Batched LFP Cells are available but also cost more and they are suitable for having cells in Parallel. Voltage & IR (Internal Resistance) matched cells are NOT properly Matched & Batched.
Fully Matched & Batched means they have been run through test cycles of being C
harged & Discharged with IR Readings AND Capacity Validation at the various set points. It is a long, tedious & costly process.
Voltage & IR Matching at a static storage voltage is of little use. This has little value because matched cells will have identical IR at 2.50, 2.75, 3.0, 3.25 etc...
HERE is one company in US and this is what they want for Matching & Batching (and not a great description either)
www.batteryspace.com