Ideal diode MOSFET circuit

[Barkuti]

Posted it yesterday in BudgetLightForum:

Having read A simple and inexpensive ideal-diode MOSFET circuit @ Power Electronic Tips, decided to draw its N-channel counterpart. See images below for comparison. Since I have no formal electronics education, this is to ask the experts if this is right (if I converted it right) and what are its practical limitations:




Speaking of low nominal voltage cells I guess a low V_GS MOSFET is preferred if used to prevent battery or charger reverse current, isn't it?

Cheers and have fun

[spec]

 Hi Barkuti,

Yes, the circuit that you have designed is the full complement of the original circuit, so it will have the same characteristics as the original circuit, except all polarities will be reversed, as you show.

About MOSFET gate threshold voltage (VGth): The VGth must be low enough so that the MOSFET turns on fully with a low battery terminal voltage. That is the criteria, rather than back flow. There are many low VGth MOSFETs available, both N and P types. The FDS6575 PMOSFET, in the original schematic, has a VGth of 400mV to 1V5 and turns on to a low drain/source resistance (Rds) of 17mR at 2V5.  https://www.onsemi.com/pub/Collateral/FDS6575-D.pdf