I need to make a power switch (on the very cheap) for an electric vehicle.
The battery bank is a 8s (29.6 Vnom) LiPo pack, powering an ESC which drives the motors.
Max continuous current to be drawn through the switch is approx 120 A. Peaks can be expected at about 180 A or so, but very infrequent/hardly at all.
The constraints are that the circuit must be powered from the battery pack, and not draw much/any current when in the off state. There are also some dimensional constraints (ie that the entire solution shouldn't be bigger than like 50mm x 50mm x 20mm or so).
I would imagine that I would need a mechanically actuated switch at the rated voltage, that enables a contacter of some sort (mechanical/electrical/solid state).
I've been doing some research, but I need a little advice as to what I should go with for a super cheap solution.
So far I've come across:
MOSFET switching circuits
Solid state relays
Some of these might require a DC/DC converter or something to get the voltage down to useful levels to engage the switching circuitry.
Does anyone have any other ideas and could someone suggest what the best (cheapest) option would be to go for here?