Voltage Drop
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=14574
Printed Date: June 03, 2024 at 11:49 PM
Topic: Voltage Drop
Posted By: Okoboji
Subject: Voltage Drop
Date Posted: June 07, 2003 at 11:43 AM
I resently put in a head unit in a friends old fire bird and a certin times the head unit powers down suddenly and then turns back on... it will happen when he turns on head lights or when he shifts out of park..... i tested the # of volts going to the head unit and sure enough i watched my muti meter go from 12 to 9! then back up..... i figured i could use a capasator to fix it. Does any one see any thing wrong with this set up im about to do?
Replies:
Posted By: trusdamanr
Date Posted: June 07, 2003 at 12:36 PM
what does the meter show on the battery when the car is running, if the car is off and it does that could be looking at a bad cell in the battery, but there is defentliy something wrong with charging system, need more info i.e. whats the voltage when the car is running,how is it wired, cripmed together,soldered, wire harness, also wheres the ground ..
Posted By: xetmes
Date Posted: June 07, 2003 at 1:16 PM
yea that doesnt sound like something i would just slap a cap on, Head units usually dont draw all that much current so look into the battery voltage and see if that does the same thing.
Posted By: BigBlue2002
Date Posted: June 07, 2003 at 2:04 PM
I had the same problem with my 68 Barracuda. I found out that when you went past REVERSE, the backup lights coming on for a second with the headlights on, drew enough current to kill the electronic radio. This would only happen at idle when the alternator didn't put out enough to keep it from happening..
The fix.. several things
1. Upgraded the alternator to one that put out more at idle.
2. Rewired the radio to a better hot lead (one not attached to something like the airconditioning fuse or something else that pulls alot of amps)
3. Put the headlamps on a relay system. That kept the headlamps from pulling through the dash wiring and made all my interior wiring much more reliable. Dash lights burn brighter now, radio doesn't cut out, etc...
Good luck!
Rob Robinson
Posted By: Okoboji
Date Posted: June 07, 2003 at 2:47 PM
Im not talking about a really big cap like a 1/2 f or some thing i picked up a small one at a electronics store i think in is like 500 uf (micro frauds)
Posted By: MAXST
Date Posted: June 07, 2003 at 4:07 PM
it shouldnt need a cap for that... thats a wiring issue... go thru and look for a loose connection. thats most likely the problem.
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I need quality equipment, feel free to donate.
Posted By: Big Purds
Date Posted: June 08, 2003 at 10:19 AM
its farads to begin with...
a cap is not the answer to the problem...wire the head units constant lead directly off of the battery, and do as BigBlue suggested and relay the headlights...if this problem persists beyond that you will really need to hunt down the problem in the car...there is more than likely a loose connection or short or something somewhere in the vehicle that is causing this to happen...
people who dont understand what a cap is for shouldnt be using them...
Posted By: LittleBill
Date Posted: June 08, 2003 at 10:53 AM
make sure u have a clean ground connection to i had voltage drop when i had a bad ground, probably easiest solution though would be to direct wire to the battery with a fuse, it won't go out then garenteed
Posted By: Okoboji
Date Posted: June 12, 2003 at 6:16 PM
HAHAHAHA to all of you i checked the conections and every thing was fine so my choises were make my friend buy a new alternator to fix a small prob. w/ his head unit or try the cap... a guess what i hooked up the cap and every thing works fine in fact better than fine... his head unit not only doesnt turn off any more it stays on after he turns the car off, for about 5 sec. and he thinks that is so cool!!!! (i wired it to the acc power lead) so hahaha to Big Purds... ya i know what a cap is and how it works... just cause i dont know how to spell farads doesnt mean any thing...
Posted By: xetmes
Date Posted: June 12, 2003 at 6:37 PM
But you also put more stress on the alternator causing it to charge the cap everytime the car is started, a cap acts like a short circuit when it is first charged, and thats a good deal of current draw that the alternator must then recharge. Maybe instead of trying to prove people wrong you should listen, Big Purds knows what he is talking about.
Posted By: D148L0
Date Posted: June 12, 2003 at 6:42 PM
Okoboji, two things: first, once I stepped up for you when somebody was being rude with you. and now u do the same thing to someone that knows a lot, A LOT more than you. in fact, and i'm sorry to say this, I have read your posts and believe me, you still need to read a lot before attempting to do an install. Second, if I got u right, did you actually connected the cap to the acc power lead? Finally, do you know why I like this forum? because of the kind of people in it.... people that don't laugh (well, at least they don't post it) after reading your posts (or mine in that case, I'm no expert either...), instead they encourage you to learn and give knowledge for free...
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D148L0
Posted By: Okoboji
Date Posted: June 12, 2003 at 7:14 PM
I must appologise.... i dont like it when people say i dont know what im talking about when i know i do.... big p. i know what a cap is... i know that it is make up of magnietic plates w/ an eletrolite solution inbetween them i understand that it acts like a gas tank in that it fills with electrons and then the load draws power from it accordingly.... and please dont start a post off with "ok first off its frauds" thats kind of rude... and saying that "people that dont know what caps are shouldnt use them" is not good advice but once again im sorry for being rude. I, like D148L0, love this forum because it has lots of kind people in it that love car audio as much audio as i do ------------- Okoboji
"Yo I wanna buy a system so big it blows women's clothes off!"
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