Battery backup for stereo settings?

[Faze3]

Why oh why don't modern electronic stereos have battery back-ups to store/retain stereo settings? So that way when the battery's disconnected, you don't have to spend 20 minutes re-setting the clock and your favorite radio statons..

Looking for info on something I can place in-line in the power line to retain the settings. I've seen something on-line before in another forum (post long since gone) from Ratshack or elsewhere that would retain one's stereo settings. Its a simple battery backup.

Anyone seen this too? Know what its called?

[jethro_3]

Did you replace your stereo? I just unhooked mine last night and did not loose any settings other than the clock. Mine is still completely stock.

[zagrot]

yes, there is such a device and it will also keep the ecu from resetting should you have to remove the battery. i've seen one for sale that was a spiffy plastic one piece deal, but if you are only concerned with function then take an old cigarette lighter powered device (don't use a cell phone charger or any other adapter with an intergated power transformer) and cut the cord so you have about a foot of wire attached. now go to radio shack and buy a 9volt battery adapter (for the small rectangular batteries) a pacage of diodes (tell the clerk that it is for use with 12-14 volts) a soldering iron and a roll of solder (you'll probably find a use for it later as well) and some heat shrink tubing.

1. strip all of the wires about 1/2"
2. put a 4" medium diameter piece of heat shrink on the wire attached to the lighter adapter.
3. split the wires that go to the cigarette lighter adapter so you have two single strands about 3" long. you will put small heat shrink on the single wires before you solder them.
4. (maybe i should have told you that you need a continuity/ multimeter as well. um, go back to radioshack. what's a project without umteen trips anyway?) find the lead that has continuity with the contact in the center of the adapter. this is the positive contact (but to be sure, take your multimeter to the cig. lighter and test it anyway). solder the red wire to the lead that has continuity with the center contact on the lighter adapter.
5. solder the black lead of the 9volt battery adapter to the lead of the diode with the stripe on it (it helps to wrap the wire around the componet lead and then solder. be quick, don't leave the iron on the diode lead for ever, just long enough to melt the solder. excessive heat can damage diodes.) let the diode cool to the touch. while the diode is cooling place a 3" piece of heat shrink in the wire that goes to the outter contacts of the lighter adapter (make sure that it fits over the diode). wrap the wire around the remaining diode lead and solder. slide both small pieces of heat shrink over the soldered connections and gently heat them with a butane lighter (the heat shrink that radio shack sells will catch on fire, and if heated too strongly it will develop holes over protrousions). now slide the big piece of heat shrink over the first two and shrink it.
6. take you continuity meter and put the negative lead on the negative pole of the 9volt adapter and the positive lead on the outer contacts of the lighter adapter. the meter should read 0 ohms. reverse the leads (using the same contacts) and the meter should read infinity. note: some digital volt meters reverst the test voltage polarity in the diode test mode, don't ask me why.
7. all done. don't leave the device plugged in all of the time and i'd advise that you don't turn on any high draw devices (head lights ect.) when the main battery is out and the 9volt is plugged in. on second thought, maybe you should also get a plastic case to put the battery in incase it should leak during an overdraw.

directions for use: plug the backup battery device into the cigarette lighter (or accessory outlet if you don't smoke) and remove the main battery for required service.