power isolation on small gage / low current applications

[MotorCityFats13]

So I drew up this little scenario, what is the common diode spec or part #'s that people use in this 12vdc application... I been watching youtube videos and reading articles but they only explain the theory behind diodes and diode types, not application specific parts... also share if you have a much more easy way of achieving this final goal.

[Wicks]

Why do you need this isolation?

You'll need a MASSIVE diode to accomplish this.

Google 12v isolator.

Something like this:

http://www.sonicelectronix.com/item_61067_Stinger-S2402.html

You'll have to make sure the diode can handle the current draw you're applying.

There will be voltage drop across the diode as well.

[MotorCityFats13]

Why do you need this isolation?

You'll need a MASSIVE diode to accomplish this.

Google 12v isolator.

Something like this:

http://www.sonicelectronix.com/item_61067_Stinger-S2402.html

You'll have to make sure the diode can handle the current draw you're applying.

There will be voltage drop across the diode as well.

it will be less then 5amps draw and only using a 16awg wire... the draw up is generic and not a representative of what I am trying to learn.... the thing I am trying to do will not have any adverse effects from a variance of 11.5-14.5 vdc so I am not worried about voltage drops... I am only using one battery.... in my situation batt#2 is really the fuse box and accessory is really my headunit

I could just pass the current through a relay and this will stop the back feed.... but one diode vs 4 wires on a relay sounds like something worth learning

[Rich Schenk]

Don't really understand the point of why u want to do this? Why don't you just run a fused separate wire from underhood battery to the hu to isolate it.

[Broke_Audio_Addict]

Also curious why you want to do this?

[MotorCityFats13]

I tackled this project because it was brought up over at the explorer forums...everyone said it cant be done and with the canbus system you had to buy the over priced pac box... i patched in to the RAP feature of my explorer at the window power proving it can be done... but if you keep the HU power wire connected it makes the RAP stay active even after you open the door with the key removed.... so I disconnected the factory red wire...not a single problem but somebody over at explorer forums asked if it can be done so both wires can stay connected and I told them it works just as designed with only the one wire, but he feels like there might be a problem powering the radio off the window circuit. I know I can do a relay but those people over there want simple and what I have now is just adding 1 wire and removing 1 wire so simple anyone can do it but you always have a skeptic..... so adding 1 wire and a diode would make this person happy.... but Im starting to not want to make this one person happy and if he dont like it then buy the retained accessory power box .... this is also the same diode setup used to isolate door triggers for alarms