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Second Car Battery?

Car Audio, Video, & GPS

Car Audio, Video, & GPS
Talk about stereos, navigation, amps, subs, and all things car audio

Second Car Battery?

  • I am very puzzled by my most recent dilemma. Most people who have real power in their system, without a cap, have the issue or their headlights flickering or in my case going about half out. I know that this is a strain on my battery, and while the headlight flashing doesn't bother me, I do not like what it means for my car. I have been looking into a capacitor and seen that most are more than the cost of a new battery altogether. I plan to add a 200W speaker amp and hopefully another sub amp drawing 800W, and there is no way I would install those without at least one good cap, or a new battery. Given the financial issue here, why don't most people who have a cap just get a separate battery? The cost a decent battery and battery charger couldn't be more than $150 or $170, and most caps start at $100, could someone provide clarity please?
    1999 Oldsmobile Alero Pioneer DEH-P5900i Alpine MRP-M850 10" Alpine Type-X (2) Alpine Type S 6" x 9" Speakers (2) Alpine Type S 6 1/2" Speakers
  • i drive a 2000 intrigue basicly the same car.

    first can u list what u have installed alread and what u will be adding.

  • I've got an Alpine MRP-M850 amp wired at 2 ohms, so it's pushin 800W, hooked up to an Alpine 10" Type X in a 1.62 cu. slot-port box and thats all controlled by a Pioneer DEH 5900i head unit. I haven't decided specifically what amps ima use for my upgrade, but I have a Viper 200.4 and a Viper 1200.1 that need repair, so I'll likely use those. I would be gettin another Type X and haven't decided about speakers.

    I'm really just curious as to why most everybody with a 800W+ or 1000W+ system doesn't have a separate battery.  



    [edited by: theclashfan1 at 1:05 PM (GMT -5) on Sun, Mar 30 2008]
    1999 Oldsmobile Alero Pioneer DEH-P5900i Alpine MRP-M850 10" Alpine Type-X (2) Alpine Type S 6" x 9" Speakers (2) Alpine Type S 6 1/2" Speakers
  • theclashfan1:
    I'm really just curious as to why most everybody with a 800W+ or 1000W+ system doesn't have a separate battery.

    B/c it wouldn't fix anything - if your system is drawing more power than your alternator can supply and pulling down your main battery as well, adding a second battery is just added strain on the alternator.

    Now - if you want to wire the second battery with an isolator and go to sound competitions and listen for 3-4 hours with your system and then know you can still start the car and drive home - or if you would be comfortable doing the same thing, driving home, and then putting the aux battery on a charger each night b/c the alternator can't charge it back up.

    Basically, the options that work are:

    Do the Big 3 upgrade - ED sells kits here

    Then add a capacitor - about 2.0 F per 1000W RMS for the subwoofer amps.

    Then add a HO alternator or second alternator. 

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • I couldn't add a separate battery completely independent from my car's battery? And just charge it when necessary? I don't know too much about cars or car audio, if that's not obvious already .
    1999 Oldsmobile Alero Pioneer DEH-P5900i Alpine MRP-M850 10" Alpine Type-X (2) Alpine Type S 6" x 9" Speakers (2) Alpine Type S 6 1/2" Speakers
  • theclashfan1:
    I couldn't add a separate battery completely independent from my car's battery? And just charge it when necessary? I don't know too much about cars or car audio, if that's not obvious already .

    You could do that, but it would only help if you want to play your system when the car is off. When the car is running, it draws all of its power from the alternator (unless you are drawing beyond its capabilities). If the alternator doesn't put out enough power, the amp tries to draw more than it can handle which causes the voltage to drop, hence the headlights dimming. If it drops low enough, the amp will start drawing power from the battery, however that is not a good thing. If you have significant headlight dimming, the best way to fix the problem is by getting a high output alternator for your car.

    When the car is not running, and you have the system playing, then it will draw power from the battery because the alternator is not running. If you add extra/better batteries, you will be able to play your system longer with the car off.

    I hope this clears up some of your confusion. If you have anymore questions, feel free to ask.
     

    2005 Toyota Tacoma Access Cab Alpine CDA-9886 Head Unit Rockford Fosgate 550X amplifier Sundown Audio SAE-1000D Temp - Kicker Solo Baric L5 Temp - Kenwood Coaxials Soon - Fi Q 18, Hertz HSK 165, 120sq.ft. of Damplifier and Overkill
  • Not quite as Nphilanthro described it - you could add the second battery, run your system off it (independent of the charging system) and the system would only draw from the battery and play till the battery was dead and then you would re-charge it.

    Two things to consider:

    • Standard car batteries are designed for a minor drain on starting and then to be charged back up by the alternator - if you run one till it is dead a couple of times, it won't charge back up again.  You need a deep-cycle marine or an orbital battery which are designed for this - hence higher cost.
    • Batteries typically have a reserve capacity of about 120 Minutes or less.  I thought that was 1-amp, but I looked it up here:

            Reserve Capacity, (RC) is a battery industry rating, defining a battery's ability to power a vehicle with an inoperative alternator or fan belt. The         rating is the number of minutes a battery at 80 degrees F can be discharged at 25 amps and maintain a voltage of 10.5 volts for a 12 volt             battery. The higher the reserve rating, the longer your vehicle can operate should your alternator or fan belt fail.

    A 900W system will likely draw around 25 amps continuous, so you have about 2 hours to listen to your system before the battery dies (at 10.5 instead or 13.8V, so less power as well).  You could use multiple batteries in parallel to extend this time of course. 

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • Thank you very much guys, totally answered my question. I think I will be investing in a 5 farad Cap, that should handle all the power that any future upgrades could require. Quick question, If I was running an 1800W system (max I think it'll ever get to) with a 5 farad Cap, am I still gonna be doing some serious draining to my cars battery? Specifically, do you think I would have to worry about my alternator or even something like my car not firing up?
    1999 Oldsmobile Alero Pioneer DEH-P5900i Alpine MRP-M850 10" Alpine Type-X (2) Alpine Type S 6" x 9" Speakers (2) Alpine Type S 6 1/2" Speakers
  • Hard to say, but you need to understand how it works and what you are doing.

    The alternator charges the capacitor when the system demand is low, and then the capacitor discharges when the system demand is high.

    For most music, when there are breaks in the bass line where the demand is not high, this works fine.

    Now, if you are playing bass test tones, or if the draw from the amps is greater than the capacitor can supply, you may get into a situation where the alternator cannot charge the cap back up fast enough, the cap depletes and then your battery starts being drained.  At that point, you would need a HO alternator or dual alternators. 

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • I see above now that you were planning on adding a battery, but not hooking it up to the cars alternator. If that was the case, then as TigerHeli said, the alternator would not come into play. This plan would definitely work, but the downside is that you have the charge the battery when it dies and you want to use it.

    For reference, my system, which draws around 1000-1500 watts at full volume will get about 30-45 minutes off my standard battery (One from autozone, not meant for audio competition) at close to full volume. I found this out when I was working on my car and had the system on the whole time. 

    I still think getting and HO alternator would be your best bet. You wouldn't need to get any more batteries, and you wouldn't have to worry about charging an extra battery.

    A capacitor will hopefully help quite a bit. If your headlights start dimming with the cap after several minutes of hard listening, generally you can turn the volume down a little bit, wait a song, and the cap will be charged back up. 

     

    2005 Toyota Tacoma Access Cab Alpine CDA-9886 Head Unit Rockford Fosgate 550X amplifier Sundown Audio SAE-1000D Temp - Kicker Solo Baric L5 Temp - Kenwood Coaxials Soon - Fi Q 18, Hertz HSK 165, 120sq.ft. of Damplifier and Overkill