C7 A6 car audio questions

[codester240]

I have a 2012 Audi A6 Premium with the basic system. This weekend I removed the stock 10” in the rear deck and installed a 12” sub on 1000watt Jl amp. A couple questions, first I was wondering if anyone’s added a second battery in the trunk? Looks to be room but just wondering if the computer has an issue with this? Also I’m going to be going to a 15” i have on order and wondering if anyone’s put in a decent sized sub and played with sub and port placement?
Thanks

[OlyS6]

You technically can add a second battery, although you really shouldn't need to unless you are expecting a huge current draw, or plan on playing a high powered sound system continuously while the car isn't running. The car's power management system won't behave the same, and could put a fair bit of stress on your alternator if the car doesn't understand what's going on and keeps seeing a voltage drop.
I have 2400 watts across 3 different amps in my S6, and have been using a single battery just fine. I recently switched to a lithium battery made by Antigravity (really expensive) that has been working well. I don't drive the car much, so I keep it on a battery tender.
You might consider going with a larger capacity single battery that can be coded for on your car, or simply get a bluetooth battery monitor and a trickle charger so you can both monitor your battery's health and always ensure that it is well charged.

[codester240]

Thanks for the reply, do you get much headlight dimming? I was surprised as I’m getting a lot more than I expected considering the car comes with a 180 amp alternator. Maybe partially due to the length of wire from alternator to battery. I’m not looking to go any bigger than my 1000rms Jl amp so maybe I’ll just use it as is for now.

[supersuk]

I have two JL Audio XD400/4 and one JL Audio XD 1000/1 powering my system and there is no dimming or any issues. I'll soon be moving to two JL Audio HD900/5 amps once I get them back from JL for service.

[Mine]

You definitely do not need a 2nd battery for your installation. I have 2 80 amp Air Zenith compressors, 2 DD M1 capable of 2.5k each and a Helix 12V for my mids and highs. The charging system is pretty stout. Definitely agree with OlyS6 on the lithium. That is in my near future. Now if you do add one, I recommend a battery Isolator. This way you 2nd battery will stay charged only when your main battery is fully charged. But this is one of several ways to add one.

[codester240]

Good to know supersuk, I’ll have to do some checking, maybe the alternator is getting tired or I have a bad ground as I’m getting really bad flickering with just the JL on 2 ohms.
What are you running for subs? I have an American bass Elite 15 coming in and I’m trying to decide on sub back, port back or sub up and port facing into the stock sub location in the rear deck

[Mine]

Being in SPL over 20 years, normally with a hatch, sub up / port back. Just remember the ports wave length needs to hit you after the subs wave length. There are several possibilities if you go ported in the hatch area.

[OlyS6]

Thanks for the reply, do you get much headlight dimming? I was surprised as I’m getting a lot more than I expected considering the car comes with a 180 amp alternator. Maybe partially due to the length of wire from alternator to battery. I’m not looking to go any bigger than my 1000rms Jl amp so maybe I’ll just use it as is for now.

You should NOT experience any headlight dimming, esp since you don't have that much of a power draw. Something is definitely going on there. You may want to test both your battery and your alternator for issues.

[OlyS6]

I have two JL Audio XD400/4 and one JL Audio XD 1000/1 powering my system and there is no dimming or any issues. I'll soon be moving to two JL Audio HD900/5 amps once I get them back from JL for service.

Agree. I'm running a JL HD900/5 and 2 JL 600/4 amps without issue on a single battery.