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  1. #1
    Senior Member Strommer's Avatar
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    Default 12v 15A battery lead to car CD player

    I am installing a new CD-mp3 player in a 1992 car. It replaces an old radio-tape player. I managed to find the wiring code via Google, and I have connected the new CD player to the car's original plastic plugs (wire harness), using a multimeter to confirm the two 12 v leads (ACC/IGN, and Battery) and the ground wire. So far, so good.

    My question is about the 12 v lead marked 'battery'. (This is not the ACC/IGN 12v lead that becomes live when the ignition key is turned.) The problem is that the "continuous 12v battery lead" for the old tape player is rated at only 5 amps, while the new CD-mp3 player is rated 15 amps. The new 15A wire certainly is thicker than the car's original wiring to the battery.

    Now I assume that I do not actually connect a wire (with 15A fuse) straight to the battery so my question is where do I tap into continuous 12v, if not direct to the battery?
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    The whole problem with the world is that fools and fanatics
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  2. #2
    They call me David... The_End_Of_Reality's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    I am no expert, but I believe that you will need to tap into the battery... how else are you going to get that power

    I have a sub and amp directly connected to the battery (with a 30 amp fuse), and more powerful head unit than that... so there is no problem...

    I maybe wrong here, but the ignition is NOT the main power source, it is like a switch to the main power source ie the battery, but it is handeled by the head unit, when the IGN is turned on, it tells the head unit to turn on and it opens a path from the battery to the head unit (turning it fully on). (for amps it is the head unit instead of the ignition that controls the on/off status)

    EDIT: I bet that if you follow the original head units power lead it will tap into the batter
    Last edited by The_End_Of_Reality; 13-04-2007 at 12:31 AM.
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  3. #3
    Senior Member roddy_boy's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    Just hook into the 5A wire. It'll be all gravy.

  4. #4
    Smiling Down On Youse SurferJoe46's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    Usually the "BATT" wire is designed to keep the memory active...the clock, station settings and such...and has very little to do with the actual playing of music or radio at all.

    If you don't mind losing all your presets every time you turn off the key (ignition) then yes, just attach the two together on an ignition controlled B+ power side.
    The problem with going to the stars is only the first few hundred miles.

  5. #5
    Senior Member Strommer's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    Quote Originally Posted by roddy_boy View Post
    Just hook into the 5A wire. It'll be all gravy.
    Yes, I may do this. If I put a 5 A fuse (as was in the original set up with old tape-radio) and it blows, I could try a 10 A fuse, but I am not sure about putting a 15 A fuse as specified in the new CD player manual - this could be too much for the thinner wiring; if the volume ever goes max then something could fry.
    .
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    The whole problem with the world is that fools and fanatics
    are always so certain of themselves, but wiser people so full of doubts.

    ~ Bertrand Russell

  6. #6
    Senior Member Strommer's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    Quote Originally Posted by SurferJoe46 View Post
    Usually the "BATT" wire is designed to keep the memory active...the clock, station settings and such...and has very little to do with the actual playing of music or radio at all.

    If you don't mind losing all your presets every time you turn off the key (ignition) then yes, just attach the two together on an ignition controlled B+ power side.
    It would be best to keep the presets so I want to connect it properly. Surfer, it is interesting you say that the BATT wire "has very little to do with the actual playing of music or radio at all" because with the original old tape player set up this lead only had a 1A fuse, with the IGNition wire having a 5A fuse. But the new CD-mp3 player has the BATT wire rated at 15 amps and the IGN/ACC wire 5A.

    If I have to run a line straight to the battery, I will do it, putting the 15A fuse near the battery. Going through the car's firewall may or may not be easy; I thought if the proper way is to tap off the fuse box (I am guessing it is under the dash, not sure) then it might be easier.
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    The whole problem with the world is that fools and fanatics
    are always so certain of themselves, but wiser people so full of doubts.

    ~ Bertrand Russell

  7. #7
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    Default Re: 12v 15A battery lead to car CD player

    I normally just tap off the clock power wire. It is normally easy to access when you are in the radio cavity. It would be neater and easier than trying to get to the battery through the firewall and the fusebox is normally on the drivers side panel.

  8. #8
    Senior Member Strommer's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    Quote Originally Posted by sam m View Post
    I normally just tap off the clock power wire.
    For 15 amps? Surely the wire to the clock would be thin and rated at 5 amps or so.
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    The whole problem with the world is that fools and fanatics
    are always so certain of themselves, but wiser people so full of doubts.

    ~ Bertrand Russell

  9. #9
    tweakedgeek tweak'e's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    run the 15amp line direct to battery. go through any rubber grommet in the firewall, DO NOT go through straight steel. fit the fuse as close to the battery as you can.
    DO NOT try to connect to ignition switch or off fuse block. not many other circuits will handle the extra wattage and it can make repairs later a right pain.

    joe... in the old days the batt was just for the memory, but these days with 4x100w+ amps built in they need some decent power hence the 15amp fuse.
    Tweak it till it breaks

  10. #10
    Senior Member Strommer's Avatar
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    Default Re: 12v 15A battery lead to car CD player

    Thanks tweake. But guess what? I went down to the local auto electrician - well established business - and showed the head honcho the wiring and explained the situation. Surprisingly he told me to leave as is, without bothering to run a heavier wire to the battery or elsewhere. The old tape player set up only had a 1 amp fuse and he said to leave that in and if it blew, try a 5 A. He said that most CD players would not take nearly the 15 A marked on the wire.

    What I did yesterday was to replace the 1 A fuse with a 5A. If that blows I will try a 10A fuse (bought an assortment at SuperCheap). If the 10A blows I will run a wire to the battery.

    To clarify: the new CD-mp3 player has two 12v leads: one is the ACC/IGN and the other wire is the Battery lead marked 15A.
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    The whole problem with the world is that fools and fanatics
    are always so certain of themselves, but wiser people so full of doubts.

    ~ Bertrand Russell

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