Amplifier installation question..

Discussion in 'Gen 5 Prius Audio, Electronics and Infotainment' started by XraidedX, Dec 2, 2025 at 7:29 PM.

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  1. XraidedX

    XraidedX New Member

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    I've recently got a hair up my bunghole to upgrade my audio system. After conferring with a few of my audio installer buddies, they seem to think i want to keep my current draw on my 12v system under 40a, which i fully understand.

    Yet, there's only so much you can do with audio under 40a. The minimalist system I'm wanting to go for has around 130a draw at its peak.

    Now here's my question/idea, let me know if I'm crazy or if it's unreasonable. Since I'll only use the system anywhere near full power for around 1-2 hours a day and have around 1.5 hours where I'll be driving, but not using the system at all, could I add a 200ah deep cycle battery, that is isolated from my 12v system, and run my audio off of it. Then have a 40a 12v to 12v charger topping it off from my cars 12v system? I could also to off the deep cycle when I get home with a battery tender if it is needed.

    Again, if I'm being crazy, or it will cause some harm I'm unaware of, please let me know.
    Thanks, my prius pimps!

    Edit: It's a 2025 prius nightshade
     
    #1 XraidedX, Dec 2, 2025 at 7:29 PM
  2. broderp

    broderp New Member

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    Yes, yes you are lol ..BUT it's a cool idea.

    Can you provide some detail around the statement "I want to keep my current draw on my 12v system under 40a"? How was this determined and what "system" are you referring to? The radio circuit or the entire Prius electrical system?

    I ask because like you I am looking at upgrading by adding a subwoofer and I keep seeing "Don't use more than 30A for a subwoofer. " In fact most recommended amps in the size and power i am looking at come with a 30A or smaller fuse. So this would be a "Don't exceed 30A additional draw on the cars electrical system and not a TOTAL car system power use.
     
    #2 broderp, Dec 3, 2025 at 12:02 PM
  3. soft_r

    soft_r Active Member

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    The OEM JBL upgrade (which AFAIK makes no changes to the power delivery) is rated for 800W (66A on 12v) peak output so that's what you stay near for your ceiling.

    I'm running gear that has peak output of 100A but I obviously don't hit that level because I'm not blasting music at 50+ volume. I'd be doing severe damage to my hearing if I was getting anywhere near peak output. If I had to guess I'd say I'm probably more in the ballpark of like 50A max (and that's peak, not sustained) with how I listen and it still gets loud. My system can do 75W max to each speaker (2 dash, 2 front door, 2 rear door), and 760W max to sub.

    But I'm not just sitting there playing 40hz sine wave tones to my subwoofer. I have it dialed in for sound quality, not rattling my doors off their hinges.

    I also only have base trim level of the car so no heated seats or heated steering or whatever other notable draws could be put on the 12v system. Freeing up more headroom.

    And in case you go searching my post history, while my OEM battery did show signs of unhappiness, that was before my final iteration of two amplifiers was installed. So that was a separate issue from my audio upgrade journey. The AGM battery I've replaced it with has been holding up just fine. And prior to me disconnecting the BMS, it easily handled my amps, spending plenty of time in the 12.7 resting voltage while driving as I played music.
     
    #3 soft_r, Dec 3, 2025 at 1:14 PM
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