battery killswitch and radio presets

So My dad has a Hod Rod we built about 5 years ago, and I cant stand that the radio presets always reset when we shut off the battery kill switch.

I have the radio setup and wired correctly with the 12v switched and unswitched.. Problem is when we kill switch, the unswitched 12+ looses power(obviously)

What I did was move the ground from the radio to the unswitched side of our kill switch(direct to battery ground) this fixed the preset issue, But now the whole truck was grounded through the radio cage.. This will not work..

trying to figure out how I can isolate this issue.. I'd rather not have a "Bypass fuse"  over the posts of the switch.. Any other Ideas?

Does he have the battery kill switch on the ground, or the positive battery connection? 

In order for it to work proberly, you need to connect the radio's yellow wire directly to the battery via a 12 gauge wire and a 15 amp fuse.  The battery kill switch needs to be put on the positive side of the equation. 

The problem is that a proper and SAFE battery kill/isolate switch needs to be in the GND circuit. [Because safety-wise, that is short proof irrespective of the location of the isolation switch(es).] Hence the radio chassis and antenna and speakers need to be GND isolated. Else a separate battery used for the radio's memory (which should only require uA of current). Otherwise a +12V isolator as per Sir Idiot Esq above, but that may be unsafe, or even dis-allowed under some regulations. (LOL - I remember when GND isolation was allegedly illegal. I think a few deaths solved that issue.)

with leaving the killswitch where it is, you can run the 12v and ground wire of the radio directly to the battery with a dedicated fuse on the 12v wire. this is one way to bypass your killswitch. the other way would be to install a small 12v battery (like what they use in home alarm panels) and charger. hook the radio straight to that battery and wire the charger to what the radio is using now for power. the charger will only run when the killswitch is off and the battery will feed directly to the radio when the killswitch is on. it should last a while because the radio only uses a tiny current to keep stored settings.

soundnsecurity wrote: with leaving the killswitch where it is, you can run the 12v and ground wire of the radio directly to the battery with a dedicated fuse on the 12v wire. this is one way to bypass your killswitch.

That's the problem - that BYPASSES the isolator. All the grounds will pass thru the radio chassis and its GND wire back to the battery GND. Hence any short can still occur, though arguably with a 10A or 15A fuse in the radio's ground no fires should occur (which is usually the main reason for a battery isolator), but battery drains will still occur as does the ability to turn on any circuit. Incidentally, the ground isolation is NOT a killswitch - it will not kill a running engine. Hence why battery isolation switches (for safety purposes) and engine kill switches are two totally separate implementations (despite one competitive event that I know of that combines the two, hence necessitating the unsafe practice of a +12V isolate & kill switch).

yea sorry i wasnt thinking about the fact that it is mounted to a metal frame and having a grounded antenna too.