Adding big amp under seats. Run cable from inverter?

I have an amp under the front seat, fed by a 7Ga (10mm^2) powerwire from the battery.

I wish to add a far larger amp under the other seat.

The factory wiring to the battery is quite thin, so I could either replace the factory wiring and the powerwire to the amps, or, much simpler, could run a wire from the inverter (or the jump-start-bolt) to the amps and hook it up to the powerwire going to the battery.

Anyone try the latter option?

I have a fused distribution block that has an unfused throughput so I can hook up the front and rear powerwire before it is fed into the amps.
The battery power wire is fused with 80A and I will fuse the 'inverter'powerwire with 80A too.

Any thoughts?

 

Thanks!

I have sound deadened the bootlid (gives a nice "THUMP" when closing it now) and will also do the doors and whatever keeps rattling after that.

I mostly pretend that I am into SQ (sound quality) instead of SPL (sound pressure level), but who am I kidding... I will occasionally use whatever I have on tap...

Which is 4x60W (Helix HXA400) right now (used as 2x60 for front and 1x200 for a sealed PG sub).
This amp will be driving all 4 stock speakers once I will be adding a subamp (Audison LRX 1.1k/Helix P200 (whatever fits best) used as 420/450Wrms on a single LTD (500Wrms) or as 800/675Wrms on two regular 12" Aliantes (2x350Wrms), but the tray seems slightly too small to accomodate two in a fully stealth setup (sealed enclosure instead of the tray).

Total power will probably be about 1000Wrms or less. Which with a battery upgrade to 55Ah and some common sense (not run system on full whack while lights, heated seats and rear defrost is on) should not be too excessive imho.


Still not swayed on NOT using an extra powerwire. Like a good Internet keyboardwarrior, I will keep asking my questions until someone agrees with me...

The major reason for wanting to add it is just the thin feed to the battery. What would I be risking if I improved on that using properly fused extra wiring?

 

Pretty thorough and neat job!!!

Wouldn't that be a Prius III? Whenever looking for info on my Prius, I type in 2008 instead of 2009, saves me from igoring all the Prius III results... (At least in the Netherlands, Toyota sold both my Prius II and the Prius III in 2009).

I'm running similar power to you, but my amps are all class AB, so less efficient...

 

Something like this?



(It's not a bandpass and only 12", but I may try to sqeeze these subs into a stealth closed enclosure that replaces the tray).

 

Frodoz, I did a quick calculation and assuming 7 Ga factory wiring and a 6m run, it will drop about a volt on 100A. Where I am worried about too much voltage drop 'reaching' the amp, this might actually be a good thing here (not good for the amps, but better for the Prius).
By the time the inverter voltage sags under 13V (at the battery through voltage drop in the wiring), the AGM battery is about to start contributing. So using your proposed method of running a 4Ga from the battery is starting to make a whole lot more sense. (in practise I will probably use the 5 Ga (metric 16mm^2) I have lying around which I'll add to the 7 Ga for two separate runs, negating the need for fuses and a distribution block under the seats.)

Thanks everyone for helping me get a (hopefully) more clearful perspective on things

 

You are completely right.
Just to clarify: I had no intention of skipping the fuse between supply and amps. But my original plan had a fuse at the inverter, a fuse at the battery, and a distribution block with two fuses under the seat.

This will be replaced by a single 80A fuse (or possibly two) feeding both the 7Ga and the 5Ga. For my intended use, I will probably not use more than 80A (not even close) and 80A should be quite safe for 7Ga, let alone the 5Ga.

Unlike my father in law's Renault Espace, where I tried to locate an occasionally occuring short and traced the 30A fuse to 8Ga wiring that was split into smaller ones several times up to as small as 20Ga... Still fused by only that 30A fuse. Now THAT is a firehazard...

I do wonder how safe all those modern cars with their battery in the boot are... My Volvo has a ~2Ga run from front to back without any fuses and virtually any car with an alternator will have an unfused run from alt to battery of several feet.

Mine are not class D... but my current amp only gets luke-warm even while pounding the sub, and the future subamp has active cooling (in case of the Audison).

That's why I am considering giving up the tray under the bootfloor. That is mostly filled with crap (although the past few weeks I have had a retractable 8ft ladder in there ).
I am a big fan of potent caraudio, but my main goal is always to use little to none of the functional bootspace. That's why I was quite disappointed that my wife didn't understand my instructions to buy this sub (I was undergoing some chemotherapy and a stemcelltransplant at that time (too bad a shape to finalize the deal myself), and I figured that was a nice present for when (and if...) I came out of the hospital ).

The above pic of the dual 12" or my current setup (single 12"in closed enclosure) are just temporary setups that are easily removed in a few minutes (Hence the blue strap to hold it down that can be loosened in seconds).