I use Contactor Controlling BMS' (Chargery) because I will not trust to FETs.
2P configurations should NOT be done with Bulk Commodity cells, only Matched & Batched ones because cell differentials will play havoc. People do it anyways, regret it and won't fess up to it when it goes wrong.
NB: Most vendors claim "Matched Cells" they are NOT ! They only match the storage voltage & standing storage IR (Internal Resistance) typically with a handheld YR1035+ battery voltage & IR tester.
Properly Matched & Batched cells go through a 3 Cycle process of Full charge to 0% SOC and back up, while sampling the IR & Impedance every 10 minutes or so which is LOGGED and also while under various load C-Rates. When Matched, the cells will behave identically during the operational cycle. A REPORT is provided with Cell Serial Numbers and test results for each.
Ideally when setting batty packs in Parallel like this, you design each to be able to operate as a Standalone take either Full Charge or Discharge loads. As a 280AH cells based pack can handle 280A out and 140A in, I would build it to support 250A Out & 125A In. Basically, build it once and not have to upgrade it later.
IE, all of my battery packs are designed to 300A spec but never see more than 200A draw and even during the Thrash Testing process, I was pulling 250A per pack and even pushed 140A at single packs to edge case test my system (remember remote & rural, can be snowed in for days at a time).
A LURKING GOTCHA !
Relay's used for BMS' are most often Energy Savers because quite honestly relay's can be power pigs, the most common are the Gigavac / Kilovac EVE series which are very reliable and durable. Non Energy savers eat watts for fun and that adds up quite fast. I use the Chargery DCC which was developed with input from a few of us here on this forum. It is Solid State and therefore uses FETS but this is a different animal than just a simple SolidState Contactor.
NOTE ON COLD TEMPS:
LFP does not like charging below freezing 32F/0C. Not all BMS' have Low Temp cutoff. If intended to be used in cold temps, a battery warmer or such needs to exist. Look at it this way, LFP likes the same temp you do with a pair of Jeans & Shirt on (no coat).
I have two 280AH packs which are Bulk Commodity cells.
I have one 280AH pack with Matched & Batched cells.
I have ATM two 175AH packs (recycled EV Grade cells from ShunBin (a total ripoff disaster written up on the forum) ) I will be switching that to one 350AH pack but I am not 100% sure as I am testing another fix for the issues.
Each of my battery packs has a Chargery BMS8T SmartBMS, with a 300A DCC (Smart Solid State Contactor), a QNBBM-8S Active Balancer and a 300A MRBF Fuse per pack.