No problem, re messing up...
It is sometimes very confusing.
First, it `hangs` on the positive supply instead of standing on ground, then using an
inverting amplifier.... Sometimes the brain doesn`t co-operate with it
And than... in my poor English.... I wrote `open` FET where I meant conducting and vise versa.
But an OPEN switch is NOT conducting....
I was planning to make the gate-resistor about 1...10 kOhm.
The gatecapacitance is mostly around 2 nF by this kind of FETs.
So, a bit extra is no problem. buckets of 0805 100 nF `in stock`.
And when this is ready, the next problem, that I did not work out yet, is `measuring` the
voltagedifference between both batteries. If < 0,5 Volt, a big relay may be switched on,
to give the 2nd battery the last bit to get charged.
Kind regards,
Edwin