OK, you are suffering from a bit of what I call alphabet soup confusions which happens to many.... the jargon get's folks mixed up.
Cells are rated for their AMP HOUR capacity, which is different than the Amps they put out.
A 280AH cell for example has exactly that, 280 Amp Hours @ 3.6 Volts, when assembled into a 12V pack (4 cells), that pack or battery is considered as 12VDC / 280AH.
Most LFP cells are capable of a 1C discharge rate. If using the 280AH example, that means max 280A out. If .5C rate discharge that means 140A out.
When looking at a BMS, they are rated for the amount of amperage they can handle. So a 4S/100A BMS will handle a maximum of 100A @ X voltage, be it 12,24 or higher. The BMS' that do not use external relays, use FETS for internal handling of the power, FETS work well but are not tolerant of working beyond spec. So if you know you will be pulling 100A on a regular basis but may have a surge that could double it, you best to go with a 200A BMS. If you stick to a 100A BMS (FET based) and all of a sudden have a demand of 120 / 130 amps, the BMS will more than fail / burn out.
Common-Port means it uses the same wiring to charge & discharge the battery pack.
Separate Port means there is a separate wire for discharging and another or charging, each can be separately disconnected by the BMS as needed.
The load you are going to pull, including Inverter, Devices/appliances have to be figured into to determine the amperage potential to select the proper BMS. 1000W @ 12V = 83A. 1500W @ 12V = 125A
You can parallel Packs to make a larger battery bank. Each pack is a separate & independent entity managed by it's own BMS. If properly wired in a parallel bus method, you will get the most balanced charge & discharge to/from the bank of packs and there really is no limit like there was with Lead Acid batteries. Have a look at pages 9-12 especially in this excellent document by Victron:
https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf
Some gotcha's that may seem wise but aren't. It sort of falls into Penny Wise, Dollar foolish thinking.
There are LFP cells from 10AH to 1000AH available on the market, of course the price climbs as the size/capacity does naturally. YES there are 1000AH cells and they are crazy pricey and not that common !
There are different ways to build packs, most suitable is to have each cell managed and preferably balanced by the BMS because that offers the most management possible. Another method is to parallel cells in packs to double the pack capacity, so instead of using 4 100AH cells to make 12V/100AH pack, you use 8 100AH Cells to make a 12V/200AH pack. The parallel pack in essence "ghosts" the cells and your not getting the best management possible and there is potential for problems going unnoticed till it's too late. The "proper" way would be to use 4x 200AH cells to make a 12v/200AH pack, or 4x 400AH cells to make 12V/400AH.
The economy factor (dollar foolish part)
Doubling cells and losing 1/2 the managing capability is foolish and a false economy on saving on BMS cost (it's not that big to pinch pennies).
Often times buying 8 100AH cells to build two 12V/100AH packs ea with 4S BMS will actually cost more than just buying 4x200AH cells and one BMS.
Remember there is a Shipping Cost and it's NOT CHEAP as LFP cells are heavy and it adds on top of the cell cost ! When you crunch the numbers up and compare it as cost per Amp Hour including shipping & handling plus BMS, it becomes more obvious.
At present the XUBA 280AH cells made by EVE seem to be the best price point but sales & specials come up regularly. Many of us here have bought these over the past couple of months and folks are testing & beating on them and using them, I have 16 arriving on Wednesday. See link in my signature for XUBA deal for a long thread on these as well there is a link to another long running detailed thread on them in there too.
!!! CHARGING !!!
Please be aware, the bigger the battery bank in Amp Hours the more Amperage will be needed to charge the batteries. At a charge rate of 0.5C on a 100AH pack, means 50A, a charge rate of 1C is 100A. You cannot exceed the cells limits and those vary by brand & size/capacity of cell. So however you intend to charge the batteries, you have to ensure you have enough amperage to do the job. So the Solar Charge Controller (SCC) needs to be sized accordingly and supplied with enough panel to be able to deliver that amount of amperage. An AC Charger if used, running from your AC power source also has to have enough amperage to do the job. Many Inverter/ Charger units are designed to be able to charge their attached battery banks based on their design / wattage ratings. These vary quite a bit when looking at product lines and quality / tier level.
** Some folks have built massive LFP packs 500AH+ and then think that a small 12V/30A SCC with a pair of 12V 100W panels will do the job.... NOT ! It would take forever to "trickle" charge because that will never even get 30A charge from the SCC going out. This is surprisingly quite common (hence a PLAN is a MUST before buying anything) with new to solar people. Also NEVER EVER make assumptions, 99% of the time that ends up making an ass out of oneself. Everything has to work together in cooperation to achieve the goals you have. Properly sizing a battery bank to meet your needs and wants, having enough charging capability to recharge your battery bank and to maintain it in good health a all times.
Hope that helps,
good luck.
Steve
