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Where to get power for audio amplifiers?

Discussion in 'Gen 2 Prius Audio and Electronics' started by lunarkingdom, Mar 4, 2023.

  1. lunarkingdom

    lunarkingdom Junior Member

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    2007 Prius
    Model:
    II
    Looking to upgrade the stock stereo and replace all 6 internal speakers (four 6.5" and 2 tweeters) and adding a 4 channel amplifier for the 6 stock speaker locations then adding another amplifier for some bass in the trunk. In looking into doing this I have a few questions:

    Where can I get 12v power to run 2 audio amplifiers?

    I do not want to attach them to the small 12v battery in the back of the car so where can I attach the power cables where I can pull 30 amps of 12v without causing any issues?

    I assume that they will run from the hybrid battery (there has to be a step down converter to run the electronics in the vehicle) but out of all the searching this subject in PriusChat forums all I have seen is people tapping into the two 12v power outlets (dash and center console) and that is some thin wire so I doubt pulling any amperage through them is a good idea. I wire up electronics all the time at work and have no problem adding whatever is needed to support two amplifiers, I just need to know where to tap it from.

    I have seen that people do this successfully, does this affect the life of an old hybrid battery and or fuel economy? I feel like 30 amps is a small amount of what the car uses to run but please educate me I dont want to spend the time and money for the upgrade only to have it cause a problem I can't fix.

    As always I appreciate your help and insight, this place is the best resource on the internet for the Toyota Prius.
     
  2. ChapmanF

    ChapmanF Senior Member

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    Look for the threads around here where people are talking about setting up power inverters. There are plenty of those and the considerations are the same.

    Keep in mind that the car's DC/DC converter is only active when the car's in READY mode. In any other mode, like ACC or IG ON, it doesn't matter where you tapped in, you'll be drawing from "the small 12v battery in the back".

    So, presumably, you're going to keep the car in READY mode when you are running this stuff.

    And of course as long as you're in READY, it doesn't matter if you did make your connections at "the small 12v battery in the back", you'll be drawing from the DC/DC converter, not the battery.

    So it comes down to where it's convenient to make your connections. It turns out the battery in the back isn't such a bad place to make some heavy connections. Just plan for how to make sure your amps are off when the car's not in READY.
     
    lunarkingdom likes this.
  3. Rational

    Rational Junior Member

    Joined:
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    Vehicle:
    2007 Prius
    Model:
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    I'm also about to upgrade my entire audio system in my 2007 2nd gen xw20. Not JBL. Current stereo went quiet/shrill three months ago. :(

    Just bought a new Mekede M6Pro Plus 2k screen double din head unit with 8gb ram and 256 gb of onboard storage. Nice android head unit!

    Got all the accessories and am researching how to get a full 4 channel and sub amp into the Prius. Searching and reading a lot.

    Got Image Dynamics comps and IDMAX 12 sub ready! I plan to do a custom install in the spare tire wheel well that will let me still load items in the trunk. Might use my CNC to create a custom rear deck with cutouts for the sub and amps then cover that with acrylic perhaps.

    Just need to not screw up the Prius electrical and still get everything working.

    I'll share what I learn.

    I'm guessing there's probably quite a few threads here that may already contain all the answers, so I'll post links here for you if I find them reading for the next few hours.

    But so far I've also heard most seem to connect to the 12v starter battery and just make sure the care is in ready mode. Which I think is how I have it all the time anyway and will when using two big amps and a sub.

    I may also install a second 12v Optima battery in the back as well with a second battery add on kit if that's a good idea as well. That way it will give the audio system a separate 12v system and charge the main starter batter automatically & vice versa when the voltage drops. Hope that's a correct assumption.

    Still searching on what the voltage limitation on these Gen 2s should be though. So far I've read up to 1000 watts is without issue. But I have some amps that could draw more if installed. So want to select correctly amps that won't overload the system.

    More searching and reading now. Interested in all input as well. Thanks!
     
  4. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    The 12v battery in the Prius does not start the engine. It just boots some of the computers and closes some relays. That's why they used such a small battery.

    You don't need to use a secondary battery unless you want to run your audio stuff while the car is shut down.

    You can still add one if you like, but it's extra expense and complication for the most part.

    If you are particularly worried about the limits of the car's electrical system, I would suggest temporarily installing an ammeter in line with your gear, just while you are adjusting and tuning. You'll be able to take readings of exactly how much impact you are creating, and you might be surprised at how little it is.
     
    Montgomery and Rational like this.
  5. Rational

    Rational Junior Member

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    Thanks. Smart idea. I'll look into getting an ammeter and doing just that. But is the max capacity known for a stock Prius? E.g. what's the max amps/wattage I can safely install for amplifiers into my car just so I know the acceptable range.

    I'm also still on the hunt for some of the better threads here from past users that might already have the info. Glad to read through them if someone can point them out to me. If not, no worries. I'll keep searching and reading. Thanks again for all the help found in this treasure trove of a forum.
     
  6. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    A stock Prius can produce about 1000W of continuous 12VDC power.

    The car is going to need about 300W to run itself, maybe a bit more on the worst day of winter with more accessories engaged. Most of the remainder is fair game.

    Your audio system is going to draw a little bit of power all the time, and some more power part-time. The battery is the buffer that will satisfy the more sudden demands of the amplifiers. I would encourage you to connect them to the battery. Your car has a different setup from mine so I might not explain it perfectly, but your battery has a current-sensing device attached to the + terminal. Somewhere on the outside of that device is a terminal you can (and probably should) use to feed your amps. This is also where you would introduce the ammeter for your testing.

    Connecting there allows the sensor to notice the demand coming from your audio system, giving the main DC/DC converter a heads-up that it should ramp up a bit. It also shortens the path from the current source (battery) to the current sink (amplifier) which should help prevent voltage dips in the first place.
     
    Rational likes this.
  7. Rational

    Rational Junior Member

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    Excellent. Thank you so much for this insight Leadfoot. It's very much appreciated.I'll do so.

    I received my new android head unit and accessories in the mail today so hope to being here in the next week. Exciting times.

    Thank you again.