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do I need four BMS's
#1
i am finishing my 4x14s200p 18650  li-ion power wall.
do I need four 70A BMS's as I use 3 4048 PIP's. each inverter can  draw 80A.
please advise which BMS to use except Batrium which I can't afford.
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#2
You need 1 bms per battery string or a bms that can take 4 strings such as Batrium or DIY BMS.

You need a bms that can handle the full load on one string. If you never plan to remove any string thats that the 3 inverters in total can draw from the battery bank

A 4048 can easily pull up to 8kW from the battery in short time. The max charging from solar alone is 80a but combined with ac its 160A....
8Kw at lets say lowest voltage of 40V is 200A.. Thats a single unit. 3 units is then 600A.

You need to be able to surge 600A from the Battery bank.
Having 4 strings of each 14s200p should handle this. You need atleast 200A bms per battery string at minimum if you ask me!

Will it be cheap? NO. But this is something you should design for before you start building and buying stuff. You really should get a proper BMS that can handle it. You already have tons of cells, 3 rather larger inverters.. And i guess you will power a more expensive house?

Look into DIY bms and then atleast one larger 500A ABB shunt example S5 series.
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#3
tanks for your reply Daromer, it is very useful I appreciate your advice
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