12v power selector switch source

[TheHokieHoopty]

I'm looking for a basic switch for my radio that will allow me to select the power supply (either the bus starting battery or the "house" batteries). I've seen the big marine battery selector switches but these seem like overkill. Websites for lots of new RVs mention a radio power selector switch, but I haven't seen one and haven't been able to locate a source for one. Any leads from anyone? Thanks.

[sportyrick]

That's easy, go to your auto supply house or Radio Shack and ask for a single pole double throw switch (3 lugs on the bottom and the current rating you need) and hook your radio to the middle one (common) then each battery bank to each side then you will have power from one or the other. 16Ga wire would work (assuming you aren't going a long way or have a high output radio) but watch out for corrosion if you hook it directly to the batteries ( I reccomend not doing that). You could also get a switch with center off so you could kill all power to the radio if you wanted to. it will be described as on-off-on or single pole double throw with center off. Be sure you fuse it for it's rated amount of current. I assume you have both batteries grounded to the bus body or frame? If not then get a double pole double throw and hook your grounds up the same way to the other set of poles. sportyrick

[Coma]

GOOD ANSWER

[TheHokieHoopty]

Coma, you're right that was a good answer. Thanks Sportyrick. I guess I was overcomplicating the issue by focusing on a task specific switch. You mention not connecting directly to the battery. I assume an add-on fuse panel for the backup battery would be the way to go. Power from the starting battery is coming off an empty accessory slot in the existing fuse panel. Thanks again for the helpful reply.

[the_experience03]

Do remember that all your presets, equalizer settings, etc will be lost everytime you switch unless you have a constant power wire hooked to a battery at all times. Every aftermarket head unit I've ever seen has a seperate wire for constant power and switched power. IIRC red is the constant power and yellow is the fused and switched power. You could switch the source of current on the yellow wire and leave the red one connected to the starting battery at all times without problems. Don't worry about it drawing your batteries down as I've gone 3 months without starting my truck and it doesn't go dead. I would dare to say that the battery will naturally discharge at a rate equal to or greater than what the head unit draws to maintain clock settings and the radio presets.

[eggman]

Yellow is constant power and the red is switched. Just finished hooking my am/fm/cd player up.

[the_experience03]

I knew I was going to get it backwards no matter which way I said it was I think I chose yellow as the constant because mine has an inline fuse....but the headunit as one as well. Oh well. Thank you for the clarification.

[TheHokieHoopty]

Hey, thanks for the input. I got two heavy duty spdt switches and wired them in today. One side going to empty ignition spots on the fuse panel and the other side going to my eventual battery bank. The "always on" power was run from the starter battery - I came to the same conclusion that it would take forever to run the battery down and I could maintain the radio memory by not going through the switch.

The current setup has one switch for the radio and satellite radio receiver. I also have a second switch set up the same way and it will control three accessory outlets (cig lighters) for an ipod adapter, cell phone charging, etc.

Now I just need to get my batteries, fuse/distribution panel, and a battery charge meter would be nice.