Help me build a nice system from the ground up

[Hardworkingman32]

I have a 2001 Corvette that needs a new audio system in it ASAP, but it all has to be able to work with my stock 110 amp alternator.
The problem is everything seems to drain the battery on this car. I can't understand why or how to fix this.
The battery will drain so bad that the car won't even start sometimes at all.

I currently have a...
Pioneer 6800BT headunit installed in the car.
Kenwood 9106D monoblock amp installed on my 110 amp alternator and battery.
Rockford Fosgate P3 Shallow mount sub thats capable of pushing 400w RMS.

With only 400 watts the lights dim when the bass hits and the battery gets drained very quickly.
How do I fix this??? Its frustrating beyond belief that my car is incapable of running 400 watts.

I'm more than willing to buy a new audio system than deal with such a headache if it is infact my components, but it has to work on my stock 110 amp alternator and not cause any issues. With that said I'd prefer a 5 channel amp setup if possible, but I can do monoblock again if needed. I just can't understand how a 110 amp alternator is incapable of running 400 watts efficiently. All of the wires are OFC wires.

I guess I just don't understand why my car is incapable of running a 400 watt system. These are the specs. https://www.kenwood.com/usa/car/amplifiers/kac-9106d/spec.html

Where did I go wrong in choosing this amp for this car. What should I look for when choosing my new amp to make sure it will work with my 110 amp alternator?

How would you rebuild this system from the ground up to make it all work on the stock alternator and battery? I have no problem swapping the gear out for something better.

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[Kickstand Premium Member]

I had a 1700 watt amp and a 600 watt amp running of the stock 110 amp alt in my cobalt without any issues
I did however upgrade the battery to an AGM battery
It sounds like either your battery or your alt are on their last legs
The car is 20 years old.
I would start with an AGM battery and the big 3 with 0 gauge wire (Alt to battery+, Battery to frame -, engine block to frame - )
Northstar and XS Power are a couple of names for batteries that should make direct drop in's which in your case should be a group 75
This should eliminate your light dim
If the battery still drains then you know the alt is the problem

 

[Hardworkingman32]

Can you by any chance tell me which xspower battery you'd recommend for my setup thats group 75. Thanks
I might want to push more in the future, but for now its 400 watts.

 

[Kickstand Premium Member]

https://www.summitracing.com/parts/xsp-s925

 

[AnthonyO 10+ year member]

My recommendation is to get the alternator and battery tested. I had this same problem in my Forester and it turned out to be a bad battery. I replaced it and haven't had a problem since

 

[Clifff150 10+ year member]

Check out the X2 Power at batteries plus. It’s a Northstar battery with an extra year warranty. Sams club has the Duracell platinum agm that is cheaper and still solid

 

[Hardworkingman32]

I tested my battery and alternator here was the results.
12.47v with car turned off and 2 mins to discharge power with headlights running, then back off again
14.2-14.4v with car running with no accessories or anything on.
13.85v with car running and lights, ac, radio turned on without amp fuseblock to battery (no power to amp)
13.60 with amp fuse connected to battery with lights, ac, and radio turned on (Amp gain at 0 with everything flat, but subwoofer speaker level at 10).

Is 13.6 good with the car running, but no amp gain at all?
How do I find a sustainable voltage for this car when using my stock 110 amp alternator?
How do I charge this battery fully I only drive to and from work 20 mins each way 5 days a week so I don't know if its capable of charging properly with only 40 mins of total drive time every day.

Thanks

 

[GBloes]

You’ve got some issue that isn’t related to your audio system unless it wasn’t set up properly. Take it to a shop that has all the fancy computers and have them check everything and see if they can find what’s going on.
Maybe the HU might be staying on after the car shuts off? So when you take it to a mechanic to check out the electrical system have them look for parasitic drain.

Once the battery is fully charged it doesn’t matter if you only drive 2 miles a day as long as you don’t listen to the radio when the engine isn’t running.

You could upgrade the battery and put in a capacitor but that’d be a bandaid, you shouldn’t have issues with a 400w sub.

 

[AnthonyO 10+ year member]

Take it to autozone. They will do a load test for free. It will tell you if the battery or alternator is bad. Sounds to me like a bad battery. Like I said my Forester was doing this. They load tested, alternator was strong but battery was on its last legs. I replaced it, no problems since.

 

[Hardworkingman32]

I put the car in a shop yesterday. It got so bad that the car would not even start at all.
I'm unsure if its audio related at all anymore as you will see from the issue I describe below, but nevertheless I would like your opinion on what you think caused this. Do you believe this to be a failing alternator or a failing battery or is it due to my car being incapable of running 400w?

Timeline of symptoms:
For about a year my car has had a strange issue where I could sometimes come out put the key in the ignition and turn the key then discover no dashlights would turn on whatsoever. When this happened I would pull the key, unlock the car door, open the car door, close the door, re-lock the car. Sit with key in hand out of ignition for 1-2 mins. Re-insert key and try again. The car would then start, but some times it would take several tries, usually it only took one to two more tries, but it would eventually start after doing this. I know that it sounds strange, but this is what I experienced for over a year. I didn't know what it was, but atleast the car would start and run so I decided to just fix it later on.

Over the course of the year I noticed some very slow cranks. Othertimes it started normally. If I drove the car somewhere, went inside and came back out. The car seemed to have a rougher start than it did when it was started cold.

Last saturday I came out to my car to leave for work.
Went to turn the key and got 0 dash lights whatsoever along with no click from the starter.
My buddy jumped me off and I drove on to work. The car started fine with a jump and I drove it the usual 20 minutes to work.
Came out after work 9 hours later. I tried to start the car the next time and it was same way. No dashlights whatsoever.
Pulled the key waited 1-2 mins using the same proceedure I usually did as described above. Gave the car a second crank and it fired right up. Granted it was a very rough start, but it fired right up.

Went home for the night, parked it.
Drove to autozone saturday to pick up some car wash gear.
Drove back home. Parked it for an house.
Drove to comcast 20 miles away. This run should have charged the battery sufficiently considering I kept the RPM right at 3000 to increase the charge rate. This is only a small amount of my total tachometer, so it should not have hurt anything.
Stopped by autozone
Same thing all over again only this time the car would not start for anything. No matter what I tried it was dead as doornail no accessories power, no door dings, and no dashlights whatsoever. Even using the normal method it would not fire up.

Discovered the positive terminal was loose and it was leaking fluid from that terminal.
Removed and replaced the sideposts with brand new ones. cleaned the positive and negative battery cable eyes with a brush, sprayed them.Then reinserted them. Car fired up immediately. Autozone showed me how that place that last installed my old battery stripped both bolts by overcranking them. They also tested my battery inside which showed as good, but the battery was leaking from the positive terminal. They said this could cause the battery to arc when the positive cable was not secure. Could this cause a voltage drain?

Drove the car home 20 mins while keeping the rpm at 3000 to make the charge speed up once again. So right now thats 40 mins of medium range rpm to charge the cars battery as fast as possible.
Parked the car.
Came out the next morning for work (11 hours later) and it was dead as a doornail again.

I also noticed that for the past week ever since I started experiencing this the fuel digital readout would start resetting itself to first say low, 10, 20, 30, 40 50, 60, 70, 80, 90, 100, and so on until it slowly climbed up to 270 miles for a full tank. Does the sound like a unstable battery issue. It reset the digital fuel readout all over again every single time the car was started. It never did this before EVER.

The shop that serviced my car told me that the alternator and battery was bad. It needed to be replaced asap. Apparently a surge had happened causing both to suffer as the other one was dying, all at the same time by the battery leaking and the positive terminal being loose. Is it strange for both components to need to be replaced at the same time? Could a faulty alternator kill a brand new battery in under a year? What do you think would cause the strange key starting issue I described above. I've been experiencing it for about a year.

Do you think this could be the cause of my electrical system struggling to run a small 400w system even on a 110 amp alternator?

Is it strange to go thru 3 batteries and 2 alternators in eight years? All for having a kenwood 9106d amp plugged up with 400w?
I was told today that my subwoofer is only meant to run at 1 ohms or 8 ohms, but my kenwood is made for 2 ohms or 4 ohms with some stability to 8 ohms. My 4 ohm dvc rockford p3sd4-12 is wired in series so its doing 8 ohms.

Is there any reason to change my whole setup due to this issue described above or do you think it was alternator/battery related that was causing it? Would a more efficient amp help the system to be more stable overall? The current consumption of kenwood 9106d is 65 amps. It has (3) 40 Amp Fuses installed on it. Will this type of current requirement cause issues with a 110 amp alternator?

My last question is about ohms
If 2 ohms on this amp is capable of 1000w rms and 4 ohms is capable of 500w rms. How much is 8 ohms outputting to my sub? Since they wired it in series.

Thank you again for all of your help.

 

[hispls 5,000+ posts]

12.47v with car turned off and 2 mins to discharge power with headlights running, then back off again
14.2-14.4v with car running with no accessories or anything on.
13.85v with car running and lights, ac, radio turned on without amp fuseblock to battery (no power to amp)
13.60 with amp fuse connected to battery with lights, ac, and radio turned on (Amp gain at 0 with everything flat, but subwoofer speaker level at 10).

None of that is how you test those things. You must take them to a part's store or auto mechanic who owns "load testing" tools.
This is 100% a problem with your vehicle's electrical system. Factory charging system on even clown-car econo-boxes should hang with modern amps up to 1200W or so without too much issue

I also would NOT buy a meme-brand battery. IMO not a one of them on the market is worth the premium price and again, you shouldn't be anywhere near needing any big upgrades. Just go down to Pep Boys, Auto Zone, or whatever parts chain is by you and get whatever their store brand premium AGM one is with the best warranty. Those have always performed well for me and warranty service if something goes wrong is just bring it up to the counter at any store in the country (save receipt to make it easier) and the kid there hands you a new one.

 

[hispls 5,000+ posts]

Is it strange to go thru 3 batteries and 2 alternators in eight years?

Assuming you only rarely drive that car, I could see batteries not lasting well (unless you leave them on trickle charge when you're not driving regularly) and assuming you are just buying remanufactured parts store alternators which can be really hit or miss quality. Parts store cheap alternator is <100$ typically and you''ve probably been buying sub 100$ batteries too so yeah, life span is about right. Non AGM batteries will fail extremely quickly if you deep discharge them (like from leaving the car sit without a trickle charge all winter when you're not driving) then running your alternator into a dead and dying battery will put extra stress on that.

Ohm's law states that P = IE and E = IR
E - Voltage
I - Current
R - Resistance
P = Power

Your amp is a constant voltage source so doubling resistance halves the current and therefore power.

Sure, a 5 or 6 channel amp would be great provided you have some fronts that can hang with more power, but there's absolutely no reason your audio equipment is the cause of this issue, more likely just the canary in the coal mine that's letting you spot it now.

 

[Hardworkingman32]

Thank you guys. I think I have it set up correctly now, but I want to be sure.
I'm pushing 39.92-39.97v out of the recommended 40.00v at a volume of 47 of 62. 47 is 75% of my volume which is the max volume I will play my music at when driving. Its not where distortion is its just 75% of the total volume. The 6800BT seems to play clear up to a volume of 56, but I figured 75% is a good cutoff point so the speakers don't get damaged.

400watts would be 40v at 4 ohms.

My single 2 ohm 12" DVC sub is wired in series at an output of 4 ohms. So is 4 ohms the resistance I need to be using to get 400 watts of power, because that breaks down to 40v max to keep the subs right that their rms rating, but not exceed it. Do I add the two voice coils together to get the resistance I need to use under ohms law or do I use 2 ohms like sub is called since it is a 2 ohms dvc sub? Thanks

I know that music is dynamic, but I want to be sure I am not using too much power on my new 110 amp alternator. I have been thru 3 batteries and 2 alternators so far in eight years. I think its due to me running my audio system too high. I have had alot of problems out of my electrical system with this car so I feel like this method is safer.

According to ohms law 400w at 4 ohms only uses 40v | 10 amps out of my 110 amp alternator, but if I should configure it for 2 ohms let me know, because thats 28.28v | 14.14 amps out of 110 amp alternator.

When I configured the sub for 40.00v for a 4 ohm load using a DMM I did the following.
Step 1). I reset the headunit first.
Step 2). Once it had reset it. I set the EQ from the default powerful mode to flat eventhough for some reason pioneer headunits default to the powerful mode, next I went to speaker level controls and turned the subwoofer up to 10. I left the fronts and rears at 0, then I switched over to bluetooth and re-paired my phone for BT use, then while I was in bluetooth settings I turned the SLA setting up to 4.
Step 3). Finally I turned off all bass boost both on the headunit and the amp, turned off all loudness on the headunit, turned off all lpf/hpf filters in the headunit itself, but I set the amp's lpf to 80hz, then I turned the gain up slowly watching the voltage until it reached 39.92-39.97v

During my configuration I used this exact 40hz test tone under bluetooth mode



Did I do it right using the DMM or did I miss a step on my configuration that I need to correct?
Thanks


I really want to be sure on my voltage setting that I did here.
My sub is Rockford Fosgate P3 Shallow Mount 2 Ohm DVC 12". Its capable of 400w RMS/800 Peak
Do I use a 4 ohm voltage load or a 2 ohm voltage load when configuring. It seems like my sub is wired in series.
Given the fact voice coil 1 red has a jumper wire going to voice coil 2 black. Then the speaker wire connected to voice coil 1 black and voice coil 2 red.


The sub box itself says its a P3SD2-12

I used this calculator to get amps and voltages

https://ohmslawcalculator.com/ohms-law-calculator