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Flashing lights when bass kicks

Discussion in 'In-Car Entertainment' started by Jay, Apr 12, 2007.

  1. Jay
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    Jay Member

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    [Apr 12, 2007]
    Not sure if this has been discussed before but each time I turn up the volume all the lights seem to flash slightly.

    What can I do to overcome this apart from keep the volume down?

    Do I need a new battery?

    Any suggestions?
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  3. Bash_A3
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    Bash_A3 Member

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    [Apr 12, 2007]
    Fitting a Capacitor worked for me in a old setup I had. I understand these are frowned upon though.
    #2
  4. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 12, 2007]
    They're only frowned upon because they only work in very specific circumstances, where the power needed from the battery is borderline "too much". Generally they are just a band aid masking a deficiency in either the battery or the wiring. If this the case they won't work for very long. They get a bad press because they are mainly used purely for show on Saxo's, where all they're really doing is proving the owner either doesn't know what he's doing or has insufficient cabling/knackered battery.
    I take it the problem described is when using an aftermarket amp/sub setup. How has the amp been wired up? It should be straight to the battery, but some ICE installers take a short cut and wire it to the 75x terminals under the steering column. This means the amp is drawing heavy current from a circuit never designed for the job and you'll get dimming lights.
    If it is wired to the battery then chances are it's a sign that either the battery or alternator is on its way out, or you are powering a very large system (over 1kW RMS) in which case a powercap might work, but more likely you need an uprated alternator and associated wiring upgrade. There's an outside chance it could just be a bad earth from battery/alternator to chassis, so worth checking this hasn't corroded.
    If the stock system is causing dimming lights then your battery must be really knackered.
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  5. Jay
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    Jay Member

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    [Apr 13, 2007]
    The amp's wired straight to the battery... using your diagram. The factory system was fine.
    I'm running a Alpine SWR-1242D and a Alpine V12 amp 600W RMS.
    I take it that replacing the battery with a stronger one wouldn't do much good then?
    #4
  6. Bash_A3
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    Bash_A3 Member

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    [Apr 13, 2007]
    Nice explanation Andy :)
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  7. Jay
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    Jay Member

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    [Apr 13, 2007]
    on a different topic, Bash....whats purpose does the Hyperboost DV serve? Does DV stand for dump valve or diverter valve.....sorry my knowledge on cars is not too good.
    #6
  8. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 13, 2007]
    you shouldn't be getting dimming lights with only 600w. Looks like your battery or alternator needs replacing.
    I take it the dimming lights are while the engines running?
    You they still dim at high revs?
    #7
  9. dualmono21
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    dualmono21 Well-Known Member

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    [Apr 13, 2007]
    check your charging system
    if you have a multimeter see what the voltage is before and after you start the engine

    with the system playing loud and the lights flashing check the voltage on the battery if it starts dipping below 11 volts this could be causing the problem

    rev the engine to see if the voltage increases

    check the amps wiring make sure both the live and earth are the same size if there not this could be your problem with that system i would reccomend at least 4 gauge cable which should be fused within 18 inches of the battery for safety

    andy is correct in saying that a storage capacitor is only of use in certain systems this is not one of them
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  10. Jay
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    Jay Member

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    [Apr 14, 2007]
    Yes the lights are dimming while engines running....I actually discovered this when I stopped at some lights and saw them bouncing off the car in front.

    I was hoping it wouldnt do this at high revs but noticed the same problem on the motorway.

    The V12 amp shows how much voltage is going into it when engine is both on and off. I've noticed its just over 12 volts when the engine is on.

    Is this right?
    #9
  11. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 14, 2007]
    The amp is causing the problem because it has a better route to the battery than the rest of the electrics, causing a momentary voltage drop when the bass kicks in and the amp draws the most current.
    A powercap may actually solve the problem, but most likely will just mask the main problem which is either the alternator and/or the battery.
    How old is the battery? They only realistically last 4-5 years.
    For the sake of £70 I'd replace the battery for a decent Bosch Silver top. It's a quick job and never a waste of money.
    If this doesn't solve the problem then you need to look at the wiring to/from the alternator. Upgrade the large gauge wiring, especially the earth straps and then finally replace the alternator. The alternator should be able to maintain 14.4v at highish revs even with a 600w amp running off it unless the battery is knackered or the wiring is shot.
    I've got 2 x 300wrms V12's running in my B5 and don't get so much as a flicker on any of the other electrics, but the alternator was replaced 4 years ago and the battery is only 2 years old.
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  12. Defratos
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    Defratos You’re Dethpicable!!

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    [Apr 14, 2007]
    Hey Andy why not get a red top battery? I've been looking at Optima's website:http://www.optimabatteries.com/publish/optima/europe/en/config/product_info.html.

    I've been getting a problem recently. Everytime I come to start the car the battery seems to be dead, I can usually just about switch it on without a jump start but I have to pump some petrol which I don't think is good. The car is 5 years old and I think it might just need a new battery, so Which one would be better, silver or red top? with the setup I have in the car (sub, amp, etc..) cheers for any help :beerchug:
    #11
  13. MiT
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    MiT Work Hard, Play harder!!

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    [Apr 14, 2007]
    It says to use yellow for car-audio systems.
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  14. Defratos
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    Defratos You’re Dethpicable!!

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    [Apr 14, 2007]
    as far as I've understood yellow top battery is for internal use i.e. in the house or in conjunction with a standard car battery with the yellow one being in the boot or somewhere else as an added battery. My bro has this on his car, it works ok but it's not at its best on ignition which is where I believe I need it most
    #13
  15. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 14, 2007]
    I just always trust Bosch, don't know why and for the money they're superb value. They also look a whole lot more capable than the girlie Optima range (not suggesting this should be high on your list of criteria when choosing a battery, but works for me).
    [​IMG]
    [​IMG]
    #14
  16. Jay
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    Jay Member

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    [Apr 14, 2007]
    Thanks for all the replies....looks like a new battery it is then.
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  17. dualmono21
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    dualmono21 Well-Known Member

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    [Apr 14, 2007]
    even at tickover an alternator should provide a constant 14.4 volts
    if it isnt then it may well not be your battery thats at fault

    get the battery checked if one of the cells is down then fair enough new battery time

    re-check your terminals and make sure they are protected from corrosion
    if there is any corrosion remove the terminal and clean it up
    after you have replaced it use something like vasoline to stop it happening again
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  18. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 14, 2007]
    It should do, and the idle should increase with any heavier load (as it does when you switch the a/c on), but it can't react quick enough to the short sharp power drain of a high power sub, which is why you get the dimming lights. If the battery is good then it should be able to provide the additional surges needed without dropping voltage, which is where the powercap comes in I guess.
    Just a whole lot cheaper replacing the battery than the alternator, and basically as soon as a battery is 12-18 months old it's performance will start to wane, so as long as the old one is not fairly new then it's still a wise investment.
    #17
  19. dualmono21
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    dualmono21 Well-Known Member

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    [Apr 16, 2007]
    andy a battery is capable of welding a spanner directly across the terminals allmost instantly even with the voltage showing 11 volts its ability to supply current in one big gulp is second to none
    supplying an amplifier with enough to power a subwoofer
    compared to this is chicken feed
    it does not have a problem with supplying either voltage or current allmost immediatedly
    what a battery can suffer from is poor recharge which is why you get the flashing lights syndrome in the first place
    putting in a powercap in the wrong circumstances only increases the demand on the alternator itself as ultimately this is where the electrical power is generated nowhere else
    i agree if the battery is showing signs of distress (such as a cell down or inability to hold voltage ) then by all means change it but do not change it without checking the component that charges it in the first place
    this can be done easilly with a simple multimeter
    #18
  20. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 16, 2007]
    Yes thanks I know how a battery works.
    What I'm saying is that there's no full proof method for determining this kind of issue. You certainly can't do it easily with a multimeter as the voltage drop only occurs for a fraction of a second under load, and we already know it's dropping voltage somewhere.
    The battery is always the most likely candidate as it's performance will wane almost as soon as you start using it, so this would not be money down the drain even if the problem lies elsewhere. For £70 it's the easiest and cheapest swap out, even just to eliminate it as the cause. The alternator should be good for at least 120k miles, and if faulty, would be displaying other symptoms. At £230+ fitted it is not a cheap or easy fix.
    If the battery is suspect then the amp will be pulling short sharp bursts of current which the battery cannot supply, thus the dimming lights. A powercap in this instance will provide a reservoir to overcome this, but will ultimately be masking the real cause.
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  21. dualmono21
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    dualmono21 Well-Known Member

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    [Apr 16, 2007]
    its not a question of cost andy its a question of changing the right component to avoid further outlay
    if you change the battery without it wanting changing then that money is wasted just the same as blindly changing the alternator is
    far better to find out which component is broken before you attempt to fix it
    a simple drop test at allmost any garage MOST FOR FREE will tell if the battery is good or not
    a simple multimeter experiment lets you know if the alternator is charging or not
    simply measure the battery at rest (at least ten minutes after a journey)tuen on the engine and then measure when the engine is idling
    now rev the engine and see if the voltage increases if it does and it continually puts out more than 14.4 volts when the engine is idling and whilst being revved then the alternator is fine
    #20
  22. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 16, 2007]
    If only it were that simple.
    Neither components are broken, but one of them is under performing. From experience it is far more likely to be the battery than the alternator. Go to any garage by all means but they'll all try & sell you a battery at high street prices as any battery a couple of years old will fail their test. So the process is pretty redundant.
    An alternator with a failed diode will still produce 14v idling or revving. This tells you nothing. You need to test it under load, and as the load in question is a microsecond of bass, you're multimeter will not react quick enough.
    If it's putting out more than 14.4v then it's not fine as the regulator has failed and it could overcharge the battery which can damage it.
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  23. dualmono21
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    dualmono21 Well-Known Member

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    [Apr 16, 2007]
    andy if the diode or rectifier had failed then the alternator will not charge above 14.4 volts at idle in which case the alternator is at fault
    if the alternator is charging above 18 volts when the engine is at load then again the alternator is at fault
    its that simple
    why on earth do you believe this to be an intermittant fault ??

    to simply start replacing parts without first checking to see which is broken first is a ludicrous and expensive suggestion
    as for the amplifier drawing too much current too quickly it aint gonna happen if the charging system is in correct order in the first place and you aint gonna know that by replacing parts willy nilly
    #22
  24. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 16, 2007]
    Never said it was an intermittant fault.
    9 times out of 10 it'll be the battery, so why fanny around?
    £70 for a new battery hardly ludicrous or expensive.
    I think Jay has lost interest anyway....
    #23
  25. Jay
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    Jay Member

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    [Apr 17, 2007]
    Andy wins this one i'm afraid.
    New battery did the trick.

    Thanks
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  26. dualmono21
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    dualmono21 Well-Known Member

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    [Apr 17, 2007]
    it wasnt a question of winning
    if you read the posts i agreed if the battery was knackered change it
    what i didnt want you doing is changing it for nothing and then finding out it was something else
    #25

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