Solenoid as Battery Disconnect?

An automotive solenoid will allow a slight parasitic draw while keeping the coil energized like others have mentioned. If you’re sold on installing a solenoid disconnect use a mechanically latching solenoid that is designed to be used as a battery disconnect. They are cheap and plentiful and will not draw any current through the coil when the circuit is open. If you want the disconnect inside the coach why not install a simple manual one inside. Less to go wrong and achieves the same result. Sometimes it is easy to over complicate things….I’m guilty.

go online and buy an RV/marine "latching relay" disconnect

the typical 'continuous' duty solenoid/relay will on 'using power' for the coil, the whole time you have the switch on camping

in other words a continuous parasitic DRAIN

not something you want to be happening

I did a simple add to my battery box. I just installed a disconnect switch that I use only for storage. Not remote by any stretch, but it works and now I have no parasitc draw. Not sure if the pic links will work as I dont do this often....

http://s797.photobucket.com/user/Rustycampsalot/media/Disconnect%202_zpszeeyiuva.jpg.html?filters[user]=137209718&filters[recent]=1&sort=1&o=0

http://i797.photobucket.com/albums/yy252/Rustycampsalot/Disconnect%201_zpskhsyjvel.jpg?t=1517723475

I think you want a latching relay operated by a remote momentary switch.

https://pdxrvwholesale.com/products/rv-custom-battery-disconnect-latching-relay-rvc1002

https://www.prvparts.com/product-p/41968.htm

I assume you're talking about a battery disconnect for e.g. storage use.

One difficulty with a solenoid like a starter solenoid (or a continuous duty variant) is that the coil remains energized whenever the solenoid is on, so you're consuming power continually. This would probably add up to at least a few Ah per day. The disconnect solenoids typically used for this application in RVs are latching ones, where the coil only serves to throw the switch one way or the other and so is only energized briefly when switching.

I'm not sure why a key switch to control vs. a plain ordinary toggle switch of some sort, but that part really doesn't matter in the overall design.

a lot of RVs are set up with solenoids... depending on if its installed in a trailer or a motorhome, there are several ways to wire them in... as disconnect switches or bank combiner switches.
but I dont see the need for a key switch on the relay circuit anymore than you need one on the manual switch... if it accidentally gets turned off, the lights will go out, so turn it back on. no damage done.

Yes, absolutely continuous duty and rated for well more than max amps you will run.

Make sure your disconnect doesn't interfere with the emergency break away switch.

I probably want one that is rated at continuous duty.