Hi and welcome. If you want to build a MOSFET box, any kind of button that appeals to you will do because the button is not in the current path; it merely serves as a signal to the gate pin to open or close the path. I am not personally aware of any MOSFET that will handle an 80 amp load (4 x 20 amp battery, God help us) in one package and fit in a box mod, but that doesn't mean there isn't one. There are some SMT ones that are like 2 x 4 mm in size that will do 60 amps. I would suggest you look into building a parallel or quad MOSFET box; that is, one where you have a MOSFET that switches each pair of
batteries, or each battery, and simply use just the one button to turn them all on and off at the same time. I don't have a spec on which to use handy, but I will observe the newer, higher power stuff is all going to be SMT rather than through-hole. If you use through-hole, you'll probably need 4 of them. You could look on eBay for a MOSFET box kit, get the specs and just buy 4 of the MOSFETs. You're aware of the need for a pull-down (pull up, for P-chan) resistor, right?
