Researching the battery shutoff switch hookup as what others do, I decided to install the switch in the negative cable. Recently purchasing a radio to install, I see it has a wire that is needed to hook up for a memory saver to the unit. I see they have kits for this but appear as nothing but a wire and fuse holder with a 3 amp fuse in it. They install on the positive battery side of a shutoff switch ( the stud with power to the positive post) and the other side goes to the memory wire at the unit..if...the shutoff switch is in the Positive cable. I can't see any way to do this with the switch in the ground side. Am I going to have to change these cables around? As I see it , I think so.
the purpose of the shutoff switch is to not let the radio drain the battery. So....you just reset the memory when you turn it back on after the hibernation is over. Or get a more basic radio, one that doesn't have memory.
You can try putting in a small ground wire from the battery to a switch to the radio. Switch it off when the battery is going to be turned off for a long period and then reset as suggested above. Test to make sure ground does not travel thru radio back into dash and chassis when the little switch is on.
I wired my memory wire direct to a 9 volt battery. Radio Shack has the plug with wires. It's a milliamp draw and I get 2 years out of a standard carbon battery. So not to loose my memory while changing battery's I use a jumper from + side to a hot 12 volt source. Simple as that. The Wizzard
That might be the purpose for some, but for me, and many of my friends, it is a anti theft device. If my car is ever going to sit long enough to have the radio drain the battery, I put it on a battery tender
I read somewhere on the HAMB that if you put a low amp fuse between the posts on the cut off switch it still has enough power to keep the radio memory but if someone attempts to start the car the high draw of the starter will blow the fuse. Also the comment that you just reset the radio every time you turn the battery off means setting the time,all the stations, and every other function you have set.
If you have the cut off switch in the ground, you'll need to run a dedicated ground for the radio all the way to the battery side of the cut off. Make sure the radio case isn't common with the ground for the memory.
Radio memory can sit on a battery for months and not run it down. I would put the cutoff on the positive side, not negative. Doing it that way, simply run a designated power wire to the memory wire on the battery.
Yes, if the purpose of the switch is anti-theft, just put the fuse across the switch terminals. It does not matter that the switch is in the negative side. (In fact, putting it in the negative side is preferable).
Most radios have a separate memory wire ,or switching of the key would kill the memory. Put a diode inline on the memory power wire to the radio [ so power doesn't backfeed up this wire into the main harness ] Then get a small 12volt battery [ eg: 12 volt cordless drill ] and Tee it into the memory wire down-stream from the diode. If the battery is disconnected ,the diode will prevent discharging the battery if somebody accidentally turns the lights on or tries to start it. Normal driving around should recharge this battery And put the kill switch on the positive, it kills the whole harness . And while you are playing with diodes , put a heavy duty diode inline with the alternator wire [so it only feeds back to the battery] and wire this to the battery side of the kill switch. If you need to kill the engine while running the alternator charge cannot loop and keep the engine running
Like one of you suggested, buy a Battery Tender and be done with it. My first one has lasted more than 14 years.
It kills me when someone gives the correct and simple answer , and yet nobody reads or comprehends it. This place is classic !!
As simple as this sounds, you would need to be dammed sure that none of the radio is touching the chassis. It needs to be totally isolated. All it would take is somebody to try and start the engine, or turn on the lights etc and the whole grounded frame will try to create a circuit through this wire.
Yes I did. Just about every car radio grounds through it's own body/chassis. They sometimes add a ground wire to the harness for some applications where the body isn't grounded correctly.[if you put a multi-meter across the ground wire and the radio body ,it is the same] I have yet to find a radio with a separate ground for the memory. The memory usually has a dedicated power feed but not a dedicated ground . So for simplicities sake ,are you suggesting we make own custom radio ,or to hunt down one made from "unobtanium" I would rather fit a cut-off switch and a 50c diode on the power side to make it failsafe
So you are saying that you are of no help to a guy who's done his research and put his cut off on the negative side. Of course, to keep things simple as possible the logical thing to do is make your own radio That's clearly that has been suggested here but you came up with that all on your own. If the continuity to the chassis for a ground path is provided thru the radio case , you'll have a custom radio install to challenge. Obviously there's problems to solve if you want this 1 integral component (radio memory) to remain in a system that you are trying to disconnect. Custom problems do need custom solutions Maybe I'm of no help to guys who can't reset their radio's clock
I can't see how your method can help the OP that has already purchased a radio. Or the average DIYer that has an "off the shelf" radio mounted to a medal dash. If you've got a mid 80's Mitsubishi Mirage or Sigma your method would work fine. The cradle in these cars are mounted to the plastic dash and have a ground wire from the cradle to the chassis [just run that wire back to the battery] If you have a fibreglass hotrod it would also be ok as long as the radio is isolated in the fibreglass dash As I posted earlier, I would rather install a 50c diode than to f**k around trying to isolate a radio from the frame. I've been involved in cars all my life ,and one thing I have observed is.... A lot of people have no respect for your property. People will touch things ,and Kids will push buttons and play with things. And as an owner we all do absent minded things [forget shit] It is similar to installing an Auto trans without a starter isolating switch , you may get away with it but all it takes is one moment of stupidity and the results can be disastrous
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