how much does a deck draw when turned off
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=121913
Printed Date: May 17, 2024 at 6:32 PM
Topic: how much does a deck draw when turned off
Posted By: tegguy
Subject: how much does a deck draw when turned off
Date Posted: May 19, 2010 at 10:18 PM
Ok so I built a garage stereo using car audio components. It consists of:
- 3 Computer power supplys
- 2 amps
- Alpine CDE-102 Deck
- One switch
- a Few LED's
Currently I have it all wired up so the switch shuts off everything. The problem with this is when I turn off the switch I loose all the presets. I came up with an idea to wire in a 12 volt AC adapter of a house hold item. It's 12 V 200 mA. I wired in two relays so when I shut off the switch it uses the AC adapter to hold the presets. My problem is it doesn't work when I turn off the switch I still loose presets.
- Is 200 ma enough to hold presets?
- Do I need to use a cap to cover for the momentary loss of power when the relays swap?
Replies:
Posted By: blanx218
Date Posted: May 19, 2010 at 11:17 PM
the h/u shouldnt draw much at all. if you think about how long a car can sit without being started and the battery doesnt drain down, you should be able to connect the constant power straight to the AC adapter and just leave it that way. i would only use the other power supplies to power the amp and trigger the ignition turn on
Posted By: tegguy
Date Posted: May 20, 2010 at 12:13 AM
So your saying the head unit pulls pretty much nothing through the constant wire even when the deck is turned on? Or did I misunderstand what you were saying
Posted By: i am an idiot
Date Posted: May 20, 2010 at 6:12 AM
If the deck was built in the last 15 years or so. The Yellow wire is where it draws all of it's power from. The red wire is simply a voltage sense wire that lets it know it is OK to turn on when voltage is present on the red wire. All power drawn goes through the yellow wire, hence the 10 amp fuse in the path of the constant wire. At rest the 200 mil should be plenty, it probably draws less than 5 milliamps. You will have to try it without the cap and see if it keeps memory or not. If it is losing memory, you may want to try a capacitor. A relay switches fast enough that a 470 mic cap should do the trick.
Posted By: tegguy
Date Posted: May 21, 2010 at 12:10 AM
I have tried it without a cap and I loose memory. So I am assuming a need a cap. I have never used one before so how would I wire it in? As long as I have at least a 470 micro farad cap or bigger I should be good?
Posted By: i am an idiot
Date Posted: May 21, 2010 at 7:22 AM
You do not need 2 relays, try this radio yellow wire to terminal 30, large supply to terminal 87, small supply to 87A. You will need a switch to control the relay, connect it to the larger supply, then through the switch and to 86. Ground 85 of the relay. You will have to turn the switch off before you kill the power supply. If you have a cap laying around, try it, if you have to buy something, try a 3300 mic. wire the cap from the radios yellow wire to ground.
Posted By: i am an idiot
Date Posted: May 21, 2010 at 7:24 AM
The switch has to turn the radio off also. it would be better if you could turn the radio off then flip this switch.
Posted By: tegguy
Date Posted: May 21, 2010 at 9:43 AM
What do you mean turn the radio off then flip this switch? I thought a relay outputed whatever was on 30 to pin 87 and 87a not the other way around? Right now I simply have it wired so the switch I have to turn on the power supplies also activates the relay to switch the power source but i'm using two relays to do this due to the reason I mentioned above. Which wire on a cap goes to ground the long or the short?
Posted By: tegguy
Date Posted: May 21, 2010 at 9:46 AM
You can ignore the part about the way the relay works. I'm tire and realised it's a simple circuit and current can flow in either direction
Posted By: tegguy
Date Posted: May 21, 2010 at 9:45 PM
Do I need to do anything special to install this capacitor? Like charge it or anything? Is the short lead positive or negative? Would it be a good idea to put a diode in line between the power supplies and the capacitor so the voltage only goes through the deck and not feed back to the power supplies?
Posted By: i am an idiot
Date Posted: May 21, 2010 at 10:31 PM
There should be a marking on the plastic of the capacitor that indicates the negative leg. Ground the leg on the side with the minus sign markings. Connect the caps other connection to terminal 30 along with the yellow wire of the radio.. No need for a diode, the relay isolates the power supplies from each other.
Posted By: tegguy
Date Posted: May 22, 2010 at 12:30 AM
Alright i'll try this tomorrow thanks
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