Depending on my approach, there are 3 ratings I could go with:
- 30A (at 24V) - if I put the switch between the regulator output and device
- 72A (at 10V) - if I put the switch between the regulator input and batteries
- 100A - max current the battery back and BMS support for continuous drain
(Those are the max it could use, not what I would be consistently drawing.)
Ideally, I’d prefer going with 100A just so I know I know the BMS will cut power before the switch breaks.
The 3 options I see are a mechanical switch, a MOSFET (or other type of transistor), and a relay.
Mechanical switch sounds like the simplest option. But I can’t find any rated for that much current that aren’t giant.
I’m thinking a MOSFET or relay are the better choice, because then I could cheaply change the type of physical switch I’m using. Also I’m debating using 2 momentary switches that both need to be pressed as a sort of failsafe, and that sounds harder to do with a physical switch.
This is just going to be an on/off switch. So switching speed isn’t important. The main thing I care about is that it doesn’t leak much power when off or waste power when off. Ideally, I want something that wouldn’t need active cooling. But I’m not sure if that’s feasible when working with that much current.
I’m going to be powering this with 4 LiFePO4 batteries in series. The pack will have 10V-14.6V over the course of its life. Each battery has a 105Ah capacity. So the whole pack will have 1344Wh of power.
Anyone have advice on a switch/chip that sounds good for this?
Sorry if this is a bit rambly. Since I’m not sure how to make a decision on this, I’m just trying to give all the info that could be relevant.