Intended circuit diagram I want to build a LiPo protection circuit for my quadcopter where MOSFETs are connected to the primary and secondary battery. When the voltage falls below certain value in the primary battery the voltage monitor triggers the P channel MOSFET and cut the supply from primary and simultaneously the N channel MOSFET connected to the secondary battery turns ON and supplies the power. Batteries are rated 22 V Max current is 250 A.

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    \$\begingroup\$ That would be a P-MOSFET device. Look at VTH in datasheet to get the right cut-off voltage. Would need somewhat of a schematic or more information to help you more. \$\endgroup\$ – 12Lappie Feb 16 '17 at 15:55
  • \$\begingroup\$ You cannot rely on the mosfet threshold voltage for this operation. You will need a more precise voltage reference, and a comparator of some sort. Mosftet Vgs(th) parameter varies a lot from device to device and over temperature. \$\endgroup\$ – mkeith Feb 16 '17 at 19:37
  • \$\begingroup\$ The circuit that triggers the MOSFET would be an voltage tester the indicates if the voltage in the main battery is low. When the voltage falls below say 10 V the voltage tester will output the required voltage(Vgs) to turn off the p-channel MOSFET connected to the main battery and simultaneously turn on the N channel MOSFET connected to the secondary battery. \$\endgroup\$ – Pavan Shetty Feb 17 '17 at 9:52

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