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Amp Install and Grounding Point question

Discussion in 'Gen 3 Prius Audio and Electronics' started by Lehboy, Sep 8, 2015.

  1. Lehboy

    Lehboy Junior Member

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    Hi guys I just recently installed an amp and front speaker system. I just have a minor problem because the amplifier goes into protect mode at a certain volume / level.

    I initially thought that the amp was defective (I bought it second hand), but upon emailing a shop to ask for quotes for new amps, he mentioned that I should check if the amp is properly grounded first.

    My question is what should be the ideal grounding points where I can attach the ground for the amp? The attached photo is where the ground is currently connected to.

    The amp is located near the rear battery, inside the boot storage. Amp is an Audison LRX 4.1 which just powers front speakers - Focal KRX2.
     

    Attached Files:

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  2. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    That looks fine. Except, is it just my eyes, or is the cable looping through a bracket of the spare tire took kit?
     
  3. Lehboy

    Lehboy Junior Member

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    Yeah it's just looping there - got to fix it haha
     
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  4. mrbigh

    mrbigh Prius Absolutum Dominium

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    whichever ground point closest to the aux 12V battery will work best
     
  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Where the 12 volt negative cable grounds, even? Just stack them, run the bolt through both.
     
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  6. frodoz737

    frodoz737 Top Wrench

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    Mine is under the passenger seat so can't help with a good location for yours. Just remember to keep it a very short run with correct/heavy gauge and used a bonding brush or similar to clean the bonding area of all paint, sealant or what ever.
     
    #6 frodoz737, Sep 8, 2015
    Last edited: Sep 8, 2015
  7. drysider

    drysider Active Member

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    Protect mode is usually caused by low voltage. You might check the 12 volt input at the higher volume range.
     
  8. lopgok

    lopgok Member

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    You might also check out the battery to chassis ground wire. No point using a really thick wire from the amp to the chassis ground when the battery to chassis ground wire is thin. I added a 6 gauge wire from the battery to chassis ground in my install.
     
  9. E46Prius

    E46Prius Active Member

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    Make sure it's as tight as possible. (not ridiculous tight) if the threads inside the receiver are painted, that wouldn't be good. Like when they dip the car for corrosion when the bolts are in place. Maybe clean up the threads with a chase or loosen/tighten the bolt a few times to rub any paint off. Take a file to any contact surface of the bolt and what it attaches to to sand off any paint.
     
  10. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Interesting. The domed pin on the end you hold in the bolt hole, to keep the brush centered?

    upload_2018-1-17_12-10-2.png
     
  11. Grit

    Grit Senior Member

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    Check if a set of speaker wires are grounded or crossed path some where by doing a continuity test with a dmm. 9 out of 10 times the positive terminal and or positive audio cable is grounding sending amp to protection mode at louder volume. 1 of 10 be overheating amp or defected amp. Also double check if it's bridge or stereo mode and wire up accordingly
     
  12. frodoz737

    frodoz737 Top Wrench

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    Yes.
     
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  13. KK6PD

    KK6PD _ . _ . / _ _ . _

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    Amp shutdown is caused by current starvation, improper grounding is a very good cause of this. Do yourself a favor, run two (2) 12 Gauge stranded wires directly from the battery terminals to the cars 12v battery. This will solve this nasty problem!!
     
  14. frodoz737

    frodoz737 Top Wrench

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    Respects, but not needed if you have a good chassis ground...and a lot less wire.
     
  15. KK6PD

    KK6PD _ . _ . / _ _ . _

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    That's the problem, you almost never have a "good" chassis ground. A little time, water, you get corrosion, that equals current starvation, which is the problem here. So with the couple of bucks extra you spend for a few feet of wire, you are guaranteed not to have a future problem. All high current devices, 2 way radios, power amps, and the like, really need to go directly to the battery. It's just good install practice.
     
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  16. frodoz737

    frodoz737 Top Wrench

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    You solution works, but it's a work-around.

    Standards and Practices dictate good terminations, clean chassis ground contact and sealant as required to posts where environmental conditions dictate. Can you imagine the quantity of wire and logistics needed if all electrical systems on any vehicle required a return wire back to to the battery post? It's just not practical or done that way.
     
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  17. ChapmanF

    ChapmanF Senior Member

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    Not to mention that, assuming you listen to more music when the car is READY than when it is just sitting stationary in ON or ACC, the circuit path back to the battery isn't even really the one you care about, but rather the one to the DC/DC converter in the front of the car....

    -Chap
     
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  18. skorpyo33

    skorpyo33 Junior Member

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  19. skorpyo33

    skorpyo33 Junior Member

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    Question about amp install to positive terminal battery 2010 prius. Where did you install inline power? To the bolt on top of positive terminal under red cover??
     
  20. ChapmanF

    ChapmanF Senior Member

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    Take a close look at that red battery clamp assembly. There is a high-current fuse built into it, with an accessible bolted connection for you at the other end (over the side of the battery, where the cable from the rest of the car is attached). I think it's 120 amps. It's marked, if I remember right.

    Attaching at that point gives you some advantages:

    1. You're already protected from the max current capacity of a shorted battery. If the wiring you're adding has a lower ampacity, you still need your own properly-sized fuse, but it doesn't necessarily have to be a high-interrupting-capacity fuse, because you're already downstream of one.
    2. Most of the time (if you play music in READY mode) your power isn't coming from the battery anyway, but from the DC/DC converter at the other end of that cable. By attaching at this point, the voltage drop of the battery clamp fuse is not in your power path.
    3. There is a similar high-capacity fuse at the forward, converter end of that same cable, so by attaching at this point, you are protected by high-capacity fuses from both possible supply directions.

    This is a picture of the corresponding attachment point on a Prius Gen 1 (note the battery clamp details are a bit different). Green arrow toward lower right.

    [​IMG]