Kill switch and fuse or breaker

Hopefully a quick discussion here, basically wanted to do a sanity check on my throttle and a kill switch option. Upgrading a brushed set up to learn some basics but I understand they tend to fail in a WOT position. So I wanted a handlebar mounted kill switch.

The throttle I have is your basic twist with a voltage read out seen below. Will this handle 48V going through the key switch and would it act as a kill switch when off? Or does it need another kill switch option (probably just another red manual rocker switch)?
https://www.amazon.com/QSMOTOR-Throttle-Voltage-Ignition-Electric/dp/B07D29TPM1


Definition of line color:

1.Black wire: Ground/GND
2.Red wire: +5V DC
3.Green wire: throttle Signal
4.Yellow wire: Battery Voltage In
5.Blue wire: Controller Electric Lock, Batter Voltage Out


Second question is about what anyone recommends for an additional battery protection without BMS. Solar circuit breaker at the appropriate amperage or a beefy fuse wired in series so as to not overload the batteries. It may come down to size restriction.

A few options here: https://www.solar-electric.com/pamodccibr.html
or
https://www.amazon.com/Install-Pro-Waterproof-Inline-Holder/dp/B07LH3ZWW6

A brushed controller, when failing WOT, is because the FETs themselves are shorted on. The only way to cut that off is to disconnect the high-current battery connection.

LIttle switches like those in throttles/etc can't handle that current. They are only to cut off the low-current "keyswitch" or "ignition" line that powers the brain of the controller. (which won't help in the case of a brushed WOT failure)


To have a killswitch on the bars means you have to lengthen your battery-to-controller wires all the way from the battery up to the bars and then back down to the controller.

Or...use a small switch like the one on your throttle to control a contactor. The contactor would be placed on the short path from battery to controller, and just it's control wires would go to the bars. The contactor would be wired so that it is off unless it receives power from the control wires, so it is fail-safe.

There are a lot of kill switch / killswitch discussions, some of which are in the list below. I'd recommend looking at some of those to get some idea of what's possible / used in existing builds that might be like yours.

https://endless-sphere.com/forums/search.php?keywords=+Kill+switch&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

Solar breakers are a common item used for this,,as are marine battery cutoffs, and large power connectors with a loopback (like ANderson SB50, etc). I'm using a powerchair breaker, but it's not rated for the voltage I'm using it at, so there's no guarantee it will actually work when i need it to. It has, however, worked fine for years so far, on an earlier bike, as my main power switch.

Personally I recommend using something with wiping contacts, like a rotary switch or a connector loopback, because those will self-clean the arc-residue from when the switch is opened/closed under load, and can also force a connection to break even if the cotnacts begin to weld, if the structure of the handle / etc is strong enough. Other types like common rockers and pushbuttons don't, so they can fail to operate (open or close).