Prevent HU turn off during ignition
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=78440
Printed Date: May 28, 2024 at 9:11 PM
Topic: Prevent HU turn off during ignition
Posted By: liquidsage
Subject: Prevent HU turn off during ignition
Date Posted: May 29, 2006 at 9:40 PM
I did a search but I must not be entering the right combo of keywords.... Is there a temp battery device / way to prevent the stereo from turning off during ignition? I don't want to do a dual car battery setup, but I was hoping for something small that could get and keep a charge and prevent battery drain/over-charge when it has a full charge.. It would be great if wiring directly to the cig. wire was possible. I do have a amp, but I don't care if that doesn't get power during ignition. Though if that is the case, will having an active remote-turn on wire prevent the car from starting due to an amp's power demands? If so, am i right in thinking I could use some kind of SPDT or SPST-momentary between the device and the remote turn on wire? Could a Farad capacitor by used to safely keep the HU & amp on during ignition?
Replies:
Posted By: aznboi3644
Date Posted: May 29, 2006 at 10:27 PM
What exactly are you trying to say?
Ignitions takes about 2 seconds. Stereo turns off so the starter and get the engine crankin. There really is no need to have the HU on for those couple seconds.
Also you are not making much sense.
Posted By: mustangfoo
Date Posted: May 29, 2006 at 10:34 PM
what he might want is for the stereo not to be interrupted. Like maybe he made a quick stop for his gf and shut off his car stayed inside, and when she comes back out he doesnt want his tunes paused! lol
Posted By: aznboi3644
Date Posted: May 30, 2006 at 12:39 AM
Also a cap would not help to keep the HU turned on. Question is why do you want to keep the sound system on for the 2 seconds of ignition?
Posted By: rallysport
Date Posted: May 30, 2006 at 1:57 AM
allthough i dont understand the need you should be able to simply tag into an ignition source (say at the ign harness) for your acc wire on the deck
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Posted By: liquidsage
Date Posted: May 30, 2006 at 4:41 PM
basically, what mustangfoo said....trying just to keep the HU from being interrupted. Ignition draws too much current for HU and amp. When listening to a CD, the time reference in a song is behind ~ 30 sec when the HU momentarily goes off . Also the HU reads the sound presets for a particular MP3 CD and sometimes i manually change them but if the HU is interrupted, it will revert to the cd's default setting. A minor thing, but annoying as hell. I just think I found what I need.... A tank circuit to connect with a small battery. https://carpc.kyferez.com/Products/products.php?id=10
Posted By: geepherder
Date Posted: May 30, 2006 at 8:37 PM
Ignition draws too much current? Who told you this? The accessory wire on your radio will not put a big load on the ignition circuit and will only take the small amount of current it needs. That is the best/simplest way to achieve what you want- keep the stereo powered while cranking. Just disconnect the accessory lead connected to your stereo in your vehicle harness (so the ignition power doesn't backfeed into it) and run your own fused lead from the ignition.
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My ex once told me I have a perfect face for radio.
Posted By: auex
Date Posted: May 30, 2006 at 8:52 PM
I am assuming that you mean radio shuts off while cranking/starting the car.
Voltage drops regardless of where you pull power from, the starter does take alot of power. The voltage falls below the normal level and the radio does turn off. A cap will work but it needs to be 1/4 farad to 1/2 farad(I have done this and I know it works, it may take more depending on how long your car cranks). I had to do this to a CVA1005 for a Police Detective, he would use the deck as a monitor hooked up to a camcorder and didn't want to redo the brake setup if he needed to start his vehicle and move quickly.
As far as the amp, it will probably shut off regardless. They draw alot of current and you will deplete a cap in less then a second.
If you want to double check, tap constant power at the ign harness, wire both constant and switched, crank the car, and you will find the deck still shuts off.
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Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: liquidsage
Date Posted: June 01, 2006 at 12:15 PM
I tried both constant & switched and the radio HU still goes out. I would prefer to not use a cap and I don't care if the amp doesn't get juice when cranking. I do care that whatever setup I use, the battery doesn't get drained when the car is off. So I really just need at most 5-8secs. of power to the HU. I have a 2001 Jetta, Kenwood KDC-X890 HU, Kenwood XXV-02A 25th Anniversary Amp. I have replaced batt. to ground, moving on to the alt. a bit later. My amp power run is 4gauge and the amp reads 14.1-14.5 volts when driving. I'm just now starting to take interest in cars so I may be way off base....but if I'm getting 14v's when driving I can assume that the alt -->batt-->amp power run is good. I've heard that starters / starter solenoids can draw excessive amounts of juice (and blow fuses, melt the wire) when they are dirty or faulty. It does take a few turns to start and on occasion chokes during start. (I live in LA so it's not cold). I was going to replace the spark plugs but should I expect to need an in-depth look at the starter as well?
Posted By: geepherder
Date Posted: June 01, 2006 at 7:15 PM
Yes, as long as your battery, alternator, and cabling is up to snuff, have the starter tested. I've never had a radio cutout while cranking when using ignition for the switched lead. ------------- My ex once told me I have a perfect face for radio.
Posted By: auex
Date Posted: June 01, 2006 at 10:42 PM
If you want to test to see if this is even possible to have the radio stay on while cranking(don't know why 5-8 seconds though) then what you can do is to try this: pull your radio out, run a FUSED wire from the battery to both the radio's constant and switched, then try and start your car. If your radio stays on then you can run a constant and a switched from your ign harness. If it turns off while cranking then it won't stay on. Starters just draw alot of power and the voltage drops below the minimum voltage for the radio to stay on.
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Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: gramozeka
Date Posted: June 02, 2006 at 2:32 PM
Hello
there is a reason why your stereo is turning off when you crank the car. it is connected to the accessory lead on the ignition switch. You have 4 positions off-acc-ign-start. In order to allow all the current to flow to the start systems that require a lot of energy for the start i.e. starter and it is a bigger priority than you music, all your accessories are turned off while you are cranking the car i.e. stereo, ac, fan and some others. This is done simply by disconnecting a switch inside ignition lock during start position and connecting it again when you return to ign or acc position.
It is a very good safety feature which insures good starts and safety of your electrical systems.
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