Is a KILL SWITCH actually needed?

CosmickGold · Nov 9, 2021

I've noticed that a lot of "van tour" videos, show a big red KILL SWITCH on the wire between battery and inverter. Why? Inverters come with an off switch on them already. Do they sometimes go crazy and refuse to turn off while billowing out smoke, or what?

I don't see a kill switch used elsewhere on the system, such as between battery and solar.

Most importantly, do I need to get a kill switch?

DLTooley · Nov 9, 2021

I don’t have one.

You do need a fuse or a circuit breaker. I don’t fully understand the merits and drawbacks of all the different types.

Freelander · Nov 9, 2021

I have one of those battery disconnects on my RV and never use, the only time I can think of to use at would be if you stored the RV some place without using it for a few months.
But I would recommend someway to disconnect the solar from the batteries or other items, I use a ANL fuse to do that, I mounted one between the panels and controller and between the controller and the batteries. You can never have to many fuses.

Its best if the fuse fails first before you set something on fire.

PlethoraOfGuns · Nov 9, 2021

As soon as I could, I have a big ANL fuse for my battery bank. That takes care of safety. I don't technically need to, but I installed one of those big ugly red disconnect switches right after the fuse. It's peace of mind for me in case something does go wrong, I can just flip the switch and everything is disconnected. Only thing I've used the battery disconnect switch for is maintenance things. Makes it easier than unbolting cables or fuses.

For my inverter, I needed protection, so I just put in a circuit breaker. So the circuit breaker can be used as a means of disconnect.

I have circuit breakers for my solar array. Fuses are fine, but I wanted an easy way to disconnect that power for maintenance easons.

So no, you don't need switches and circuit breakers and such, but you definetely need at least proper protection for all this stuff! At the minimum you need fuses. The switching just makes maintenance and upgrades easier.

tx2sturgis · Nov 9, 2021

I have not seen the videos you refer to, but it's possible the 'big red kill switch' might be an A-B battery selector.

Just FYI:

The typical small on-off rocker switch on large inverters is typically rated at a few amps and does not actually control the high amperage current into the inverter, it only switches the control circuits on or off. The large high current devices in the inverter always have full access to the incoming current supply.

It could be possible, ---in theory--- that an inverter might fail (shorted, overheat, etc) and the heavy duty switch would be needed to actually be able to carry the inverter current when it is operating normally...and/or shut it down completely if it DID fail in a bad way.

But...I simply use a switched DC high-current breaker. It is BOTH a switch AND circuit breaker. Keeps me happy!

Tony's Dream · Nov 9, 2021

I installed it on my battery box so I could disconnect the power from the battery power easily. I found that there are numerous things that run all the time and it drained my batteries when I stored my camper for several months.

I think he means this.......

Battery Switch, 12V 24V 48V Battery Disconnect Master Cutoff Switch for Marine Boat RV ATV UTV Vehicles, Waterproof Heavy Duty Battery Isolator Switch (On/Off)

bullfrog · Nov 10, 2021

Just keep in mind the solar panels should be disconnected from the controller before the batteries are disconnected from the controller and batteries should be connected to the controller before the solar panels are reconnected. A master cut off switch is fine for powered circuits for safety just make sure the battery stays connected to the controller when the switch is off to the other powered circuits like the inverter or you disconnect the solar panels from the controller before turning off the master switch and turn the master switch on before reconnecting the solar panels to the controller or you may damage your controller I believe.