ISP use different power grid’s power and they has inverter and generator too .

UNINTERRUPTED POWER SUPPLY. Diode I used is 1N5822 Schottky diode superfast n no delay.very low voltage drop.

Instant switch between battery and grid power because of 1N5822 Schottky diode. Circuit is very simple. Main 15v dc (positive) with 1n5822 connected directly to output switch. 15v dc connected to xl4015 board red one. Xl4015 connected to bms input output points. BMS’s extra input output connected to XL6019 boost converter. Xl6019 output with 1N5822 diode connected with switch n output. I recommend adding a extra switch between XL4015 output with bms connection .

Circuit is very simple,you can easily build it . If you want I can send you the tutorial link

Node or central connection is not in our area. Grid power different and they also have inverter for the system.

That’s why I used battery holders and soldered wires into holders.Then inserted batteries into holders.

Yes little bit of Diy stuff is good and exciting.