Seemingly differential simulation?

[Things]

Hey all,

I'm using the little Java circuit sim to try out some battery control here with MOSFETs, but i'm seeing some strange behaviour. My thoughts are that the simulator isn't getting the "ground" references correct, and as such, is using the 2 terminal inputs as differential inputs?



Is this just a referencing issue with the simulator, or am I actually doing something wrong here?

I also have an odd issue where if the threshold voltage of the MOSFET is set below around 2V, it allows current to leak through? I've heard this sim isn't the most accurate for MOSFETs, but is my circuit sound?

Cheers,
Dan

[PA0PBZ]

My thoughts are that the simulator isn't getting the "ground" references correct,

I don't get it either, where is your ground?

[Things]

There is no ground, this is a purely battery battery based system. Although in terms of what the control electronics are referenced to, this point under the blue arrow is "ground", as the 25V is the pack that will be powering the system:



I tried putting a ground reference in that position, but it did not do anything.

[PA0PBZ]

There is no ground, this is a purely battery battery based system.

Ok, but if you expect the simulator to put out some meaningful values which you expect to be referenced to something, then put a ground on that something.
The bottom connection of the battery would be a nice candidate, try it.

[Things]

Sorry, just updated my last post with more specific info.

Circuit is here if anyone can be bothered checking it out in the sim.

EDIT: OK, I think I've figured out how this is meant to work. THis section of the circuit is meant to be controlled by a IC internal to the batter pack, thus ALL output (That isn't the pack's internal protection circuitry), should be taken from the DSG FET's output pin. This way a -3V "ground" will be the ground for all external electronics to the pack, which is fine.

The problem is, i have a microcontroller I want to have control over the DSG FET also, along with the batter management IC. If I use the DSG output as the uC's ground source, it'll mean that the DSG FET will never come on, because the uC will never get power, to in turn enable the FET. Am I right in thinking an isolated power supply for the uC might be my only solution here?