Let me go backwards here...
Dunno why I’m doing this in bullet form (oh that’s right; I’m at work! *lol*), but here goes:
• The amp power should come directly from the battery. The harness may not even be used at all, except for remote start. This will of course start the million dollar question of secondary battery vs capacitor; but if you get an entry level amplifier, you can drive power from the main battery. Like you, I’m that “better-safe-than-sorry” person whose girlfriend loves to take her daughter around in my car when I’m not using it. For that reason…
• I use a secondary battery. And I use a relay that switches charging on and off when the car is on and off. It’s been a year; and it still is going strong. Winter for me is here; and having the ability to have my main battery dedicated to powering up is awesome. And in connecting the amp to that secondary battery, just because the car is off doesn’t mean your CarPC/music is too. This is a caveat I tend to embellish. A lot. Some advice on that: While an Optima battery is your best bet, they are not the only deal in town. Shop Stinger; shop Odyssey, shop XS Power; shop for any battery that will not leak acid no matter what position you put the battery in. And be sure that you get an excellent mounting mechanism for it too!
• The Venue 8 Pro looks very promising. As far as power goes, any opportunity to not use a cig adapter is an opportunity well taken. The USB hub idea works, as long as you know that your hub will only serve as a charging station for all USB items. The danger of most tablets (this one included) is that they do not connect to any external peripherals. So whatever you were considering about rear-view camera/USB camera connections, car diagnostic connections, and things of the like… you can forget about it. And what about adding extra storage via the MicroSD slot? Get past powering on an internally mounted unit, and this should be the next question on your mind.
• That alternator – truth be told; I am not sure how long an alternator is supposed to last. However, because I was “Mr. Trial-and-error,” I ended up replacing mine. I think I went from 80 amp to 100 amp or something like that. As long as your connections are correctly installed, your alternator is nothing you need to worry about. Especially if you go the tablet route.
• @Camo.b is spot on about second battery info as well as the 7” install for a “novice.” My 10.1 screen (which is the combination of a pulled LED netbook display [used in some tablets!] and a controller board for VGA/HDMI connectivity) was decided upon after years of dealing with 7” screens. And even with fabrication, the person doing will have to redo the Camry’s HVAC controls for proper placement. And they do have 10.1” tablets (some less than $200 on eBay!), so know what screen size you really want before you dive in.
• The Toyotanation.com forums - This forum will be your best friend. Look through here first to see how fellow Camry owners did their car audio setups. You will notice a few things; namely the fact there was little-no drilling! For my MACry, the only thing I had to do was puncture a hole in a grommet that already existed, and feed the power wire for the amp, and later the secondary battery-relay connection, through the hole, underneath the carpeting of the car and the underneat the car's backseat which you will have to pull out. You’ll also find information on LED bulb swap outs, and other upfit ideas you can discuss with @rray.
• Based on the tenor of this thread, the Metra kit is a necessity. Buy a couple of these early. Your fabricator will appreciate you.
• I will go through my old pics and give you an idea of how my setup currently looks. Hopefully by then, you’ll know how you want your setup to look. Because it seems you want to go the regular infotainment route, with Office 365 and the internet at your fingertips. In this plan, the tablet is your best bet, and depending on the amplifier you get (4 channel for all six speakers, no subwoofer) you may not even need a secondary battery. But if you feel yourself getting bold with a bigger build, you may require a bigger setup.
That is all… For now.
Ahhh... The joy of the holidays!
Oh, I feel the holiday love! That pie-loving, turkey-carving love of the holidays…
I’m sorry; I couldn’t resist. Anyway…
The primary reason there is a direct connection to the battery is because of current flow. Based on my understanding, the harness will provide the same power, just not enough current for a typical amplifier. That is, if you were to get a typical 4 channel amp from the likes of Lanzar, Rockford Fosgate, JL, Kenwood, Boss, Alpine or Sony, you’ll notice they always tell you to use 8 AWG or 4 AWG wiring to connect to the battery (as well as to fuse the connection, thanks @OldSpark). Thumb rule is: the shorter the number, the thicker the cable; the thicker the cable, the less resistance it has. The less resistance the cable has, the more load it can handle, and therefore, the more current can flow to your amplifier. And that current is necessary to keep those kinds of amps going, otherwise you risk frying the power supply, overheating the amp, frying the amp, or all of the above.
Now bear in mind, that’s if you use those kinds of amps.
If you use these kinds of amplifiers, only then do I see you using the harness to power it. I cannot vouch for its abilities, because I believe in subwoofers and the old-school amps that power them. But look at the reviews; check out other builds that have used similar types, and then make your decision.
Rear View Cameras
If you indeed go the route of the tablet, check out @Hexxamillion’s Altima build. He used an independent screen for his cameras similar to a rear-view mirror. This is an idea you can consider if you wish…
Optimas, Stingers, and Odysseys. Oh My!
I will not dispute/confirm the charging issues that @redheadedrod has discussed. I’m sure he went through that ordeal and came out the other side so others won’t go through similar plights. All I can say is that in my situation, I use two (2) optima yellow tops; a D35 for the main battery to start up the car, and a D51R for the audio setup. Both are 12V batteries; both charge fine with the Stinger relay isolator and all fuses in their proper places. Both just happen to require 13.6-15V from the alternator to properly charge. There have been no acid spills of any kind, and no alternator issues of any kind since this union took place.
Before I forget, the harness you speak of is already routed to the main battery. If you use the harness to power whichever amp you choose, you sort of defeat the purpose of the secondary battery. @OldSpark said it best; should you want independence from the main battery, the secondary battery is the way to go.
Until Next Time…