Hello,
I'm in the process of gathering info for my next project, which will be ESP32-controlled, PWM/MOSFET-driven seat heaters for my car, and I can't quite find the right MOSFET for this.
So far, I've been able to take measurements and work out that I will need 8 metres of heating wire per heating mat, perhaps a smidgeon more, in any case, around 16 metres in total for one seat.
I plan to use this heating wire, in the variant that has 0.3 Ohms/m resistance:
At 8 metres per heating element, that's 2.4 Ohms. To get a good heat output, I would like to connect the heating elements for the cushion and the backrest parallel, so that I would have
12V/2.4 O = 5A of current per heating element, i.e. 2x 5A = 10A of current per seat.
This is of course only the theoretical maximum, I'll probably run them at a PWM duty cycle of around 180 to 220, as most factory heated car seats are said to output in the region of no more than 80-100W per seat.
So I've looked at the websites of ST Microelectronics and ON Semiconductor, but I haven't been able to find an N-channel MOSFET with the right characteristics, i.e. 5V gate voltage, >=12V through voltage, and around 150W of maximum power, and >10A maximum current.
Could somebody point me towards the right kind of MOSFET for this application?
Other thoughts and suggestion are welcome as well.
(the ESP32 is because besides of course installing physical switches in the car, I want to be able to control the seat heaters via bluetooth app on my smartphone, because, hey, why not... )
- carguy