Wiring Inverter - how to add switch to 12V input? HELP

[neo102470]

Greetings,
I have a 1350W/2700W stand alone inverter that I'd like to put in my 2002 Fleetwood Storm (class A). I plan to mount it near the house batteries and just run AC wires to the TV cabinets, etc.

My question is how to shut off battery power to the inverter when I'm not using it. The inverter has an on/off switch on it that I can easily relocate to the interior of the RV but the inverter will still draw .5A from the house batteries at all times. I don't want to let this happen when the RV is in storage - and I don't really want to get in the basement compartment and manually unhook the inverter from the battery each time I use it.... and I don't know if the RV is 'prewired' for an inverter - but either way, this inverter does not have a 'pass through' circuit - so integrating it with the RV's power control board is not an option.

My intended solution was to put a relay to switch the + input from the house batteries to the inverter. My issue is that the inverter can draw 250A DC max and I have never seen a relay that can handle this much amperage. I assume I am just missing something and that this is easy to do...
What do I need to do here?

THANKS!

[Tincup]

I don't understand how your inverter can draw any current if it is turned off?

Are you sure the .5A is from inverter and not a phantom load?

[neo102470]

When the inverter is turned off via the switch on it, only the AC outlets go dead. The inverter is still receiving 12V from the battery and uses .5A in 'sleep' mode according to the owners manual. I think this is pretty standard.

[wa8yxm]

I use a knife switch rated at 700 amps hooked to one of the battery terminals.

You could use a heavy duty Marine quality switch of which most RV places carry at least one..

Frankly... Any switch in the line will reduce voltage to the inverter under heavy loads... and that sucker can pull some SERIOUS amprage (Figure watts/10 and you are right close)

[neo102470]

Yea, I'll probably end up using a knife switch... I was hoping to be able to set it up so I could switch it off from inside the RV instead of needing to remember to go flip the switch in the basement. It's not a huge deal... drain the battery a couple of times and I should be able to remember.

[HarleyWJones]

You can use a latching solenoid to switch the 12 volt power to your inverter. They are more common on boats than RVs. All it requires is a momentary contact closure to toggle the solenoid on, then off. The momentary switch can be any garden variety pushbutton capable of handling 1 amp at 12v. It draws no power when in either the on or off state. This would allow you to control the solenoid remotely with only small guage wire. You can even get by with only one conductor if you supply either 12 volts or ground at the remote switch.

Do a search for "battery latching solenoids 300 amp". These solenoids will do exactly what you need. There is a company named Blue Seas that used to sell them. They also make a solid state switcher, but it gives you a voltage drop of about 0.7 volts across its terminals. That voltage drop would cut your inverter run time a bit.

[BigV]

Since we are just talking about storage I would just use a battery disconnect switch.

Latching relays come in 100A and 300A. You would need the big one which is pretty pricey for something you only need to switch coming in and out of storage. The blue sea switch can handle 350A and will take up to a 4/0 wire.

[TechWriter]

Originally Posted by neo102470

Greetings,
My question is how to shut off battery power to the inverter when I'm not using it.

My intended solution was to put a relay to switch the + input from the house batteries to the inverter. My issue is that the inverter can draw 250A DC max and I have never seen a relay that can handle this much amperage.

I would not use a knife switch that has exposed metal. You'd be asking for trouble.

Use a high-amp battery disconnect switch like a Perco:
PERKO Battery Switches at West Marine

Or, if you don't have a fuse between the batteries & your inverter (something tells me that you don't), use a high-amp DC breaker:
C-Series Toggle DC Double & Triple Pole - Blue Sea Systems

The breaker gives you a fuse & disconnect switch all in one.

[neo102470]

Thank you for all the replies. Lots of great ideas...

I decided that I'm going to use an automotive style screw off battery disconnect and forget about trying to turn off the inverter power input from inside the coach. It's just not worth the money to me to get one of the 'fancy' marine switches.

Regarding inverter fuses, I do plan to use a 250A ANL fuse on the +12V input to the 1350W/2700W peak inverter.

As for exposed electrical wires/terminals, the automotive style screw off type battery disconnect, while having exposed metal, is bolted to the battery so no worries there and the ANL fuse will have a plastic cover that's designed for it so, again no worry of accidental contact with metal.

Thanks again!