I'll chime in.
4X 12V/280AH set in Parallel with a BMS each, will allow each battery "Pack" within the bank to share load & charge if properly wired (as noted in the Victron Doc). Each BMS should be able to handle the Full Load on its own, so that Full Charge or Discharge you expect to hit. This also provides failover safety & redundancy should something go awry. REMEMBER, Murphy's Laws always apply to those who are not prepared.
There are MANY BMS's to choose from and they vary in function, capability and features, of course the price point float right along with that. I will NOT recommend a BMS because it is subjective and there is no info here to base a recommend on. BUT see below.
You mention you have a Genset that can output 4800W @ 120V which translates to 40A @ 120V. Most High Frequency Inverters (known as Car Inverters, they are cheap MOSFET Based) can do X2 their rating, so 3000W will do 6000W. Good Low Frequency Inverters with heavy copper wound coils can do X3 their rating, so 3000W can be 9000W for surge handling.
3000W @ 12V = 250A from the battery bank. (without deration) so 266A with derated. Also appreciate that with that amount of amperage @ 12V, you will need serious cabling like "Royal Excelene 4/0 Fine Welding Wire" see table below.
NOW the FUGLY Part. When it comes to BMS, there are two basic types, mosFET based which typically cap out at 200A because they have to dissipate a lot of heat, there are all "one piece" and the values given for them is pretty much the max capacity for them, meaning taking it to the edge of their performance design. So typically with FET based BMS, it's suggested that it handles a minimum of 25% more Amps than expected but 50% more leaves safety margin. The 2nd type of BMS, uses Relays/Contactors to control ON/OFF states such as Low/High Volt disconnect or temp disconnect. The FET based does all this internally and that generates heat. In the case of relay based BMS, they can handle whatever the Relays are rated at, they are available from 50A to 1000A. BTW: EV's use Contactor based controls, as they are all heavy amp use. Some BMS have balancing functions (passive or active) and more, so that has to be decided upon as well. Having a BMS that can balance is a nice extra which saves having to buy a balancer separately. Typical FET based BMS, will allow for a charge rate at 50% of it's output rating, so a 200A BMS would allow 100A Charge (generally). A relay based BMS doesn't care, it's up to the relays.
Batteries: Everyone sees the big numbers and get all googlie eyed but hold up on that. The bigger the battery system (amp hours) the more OOMPH it takes to charge it. Realize that a 280AH cell can accept 1C Charge Rate @ 280AMPS ! now you will NOT be charging them at 1C rate not even 0.5C (140A) There is some serious math which I won't get into but this is enough to point out that you must consider how you will be charging. I use Solar Charge Controller and Solar Panels for charging which does up to 79A, my Inverter/Charger can also accept an SCC INput (independently) or take Grid or Generator power to charge my bank but it is limited to 50A. Another point on LARGE cells most won't mention, is the larger the cell the more potential for it to wander voltage wise, if they are "Properly Matched by Voltage & Internal Resistance) this is not a huge issue but Volt & IR Matched cells will cost a dear penny ! Simple Voltage Matched will not but you must expect deviations between cells. We are not talking about 18650 mAh cells here, these blighters are big. REMEMBER that a 280AH cell is 5Kgs/11Lbs for ONE !
FYI HEADS UP:
Well, the inevitableness of the continuing trade shenanigans, it now appears that the Trumpican's are about to clamp down on Alibaba and the like from dealing with US customers. Isn't it bad enough that the Duty War has increased costs for the consumers and the other games have reduced...
diysolarforum.com
Known Good 280AH cell vendor Luyan Tech, a sister company of XUBA electronics.
280AH x 16 pcs Bundle including shipping DDP (duties taxes paid) $1706 USD
Luyuan 16pcs 280ah Lifepo4 (lfp) 3.2v Cells Battery (bulk,Voltage & Ir Matched Only)--old Version--out Of Stock - Buy 3.2v Lithium Iron Phosphate Battery,Lifepo4 Battery Pack,Electric Car Battery Pack Product on Alibaba.com
www.alibaba.com
REF on INversion Tech LOW vs HIGH frequency:
Understand the difference between high frequency and low frequency inverters with this quick article.
www.magnum-dimensions.com
Royal Excelene Chart:
Hope it helps, Good Luck
Steve
