RIDICULOUS Voltage Drop, help me out guys.

[Defconx3 10+ year member]

I just finished installing my Directed 1500d and my Profile 75w X 4 amp. I went ahead and started my car and turned on the headunit, but there came no sound. As you would imagine, I went around to the back of the car and noticed that the power light on my profile amp was flickering (not in a periodical way, randomly) and my directed amp wasn't even on. //content.invisioncic.com/y282845/emoticons/eyebrow.gif.fe2c18d8720fe8c7eaed347b21ea05a5.gif

The first thing I checked was the remote turn on cables, which tested to be good. Then I took my dmm and measured the voltage to the terminals while the amp was off. It read out to be 14.27 V, which is good. Then after I turned on the amp, the voltage read 7.1 V, which is obviously the problem.

What has me stumped is the wiring is the exact same wiring that I used on the amp before, and it worked perfectly. The only thing I adjusted while installing the amps was the positive terminal to the battery, which I went ahead and disconnected the 1500d from and cleaned the connections and reinstalled. But there was absolutely no difference. I am skeptical about there being a grounding issue because I have it grounded in the exact same location that I had my old POS 250w lighting audio amp grounded.

I am feeling frusterated because I spent about 15 hours installing new speakers, headunit, amps, and wiring and now im running into this shit. Any pointers would be really appreciated.

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[negativezeroz 5,000+ posts]

i would imagine you have 0/1AWG power? How big is your alt? Could try the big 3 or get a new battery

If your car was on when it did this then its making me lean towards your alt..

 

[PhatTonyDeMarco 5,000+ posts]

Well a 250w Lightning amp and a 1200w Directed are in two different classes... What vehicle is this, do you happen to know your stock alt output?

I wouldnt say something was installed wrong, just that you have some major electrical upgrades up your alley. The big three is a start, do it correctly and see what happens.

Also, what size wire is going from amp to battery? If it isnt at least 4 guage, then upgrade....

 

[Defconx3 10+ year member]

Yes, I would normally say so too, but like I said, I disconnected the 1500d, leaving only the profile 75w X 4 amplifier. I have gotten that amplifier to run perfectly on the same wiring before, and there is also no dimming to be seen, which would be an indicator of battery/alternator failure.

 

[Defconx3 10+ year member]

Well a 250w Lightning amp and a 1200w Directed are in two different classes... What vehicle is this, do you happen to know your stock alt output?
I wouldnt say something was installed wrong, just that you have some major electrical upgrades up your alley. The big three is a start, do it correctly and see what happens.

Also, what size wire is going from amp to battery? If it isnt at least 4 guage, then upgrade....

Let me clairify, I have 4 guage running to the 1500d, and 8 guage running to the 4 channel amplifier. I will be running the 1500d at 2 ohms, so I don't see why I would need more then 4 guage for the time being.

Also, the 1500d is currently disconnected, I wanted to see if the power usage from the 1500d is what was causing the drop, and it wasn't. I know that my electrical system can totally handle the 4 channel amp, so I wanted to get that to work properly, then make my way to the 1500d.

 

[PhatTonyDeMarco 5,000+ posts]

Yes, I would normally say so too, but like I said, I disconnected the 1500d, leaving only the profile 75w X 4 amplifier. I have gotten that amplifier to run perfectly on the same wiring before, and there is also no dimming to be seen, which would be an indicator of battery/alternator failure.

Have you put a DMM on the battery terminals or the altenator to see if either is mysteriously low?

 

[Defconx3 10+ year member]

Have you put a DMM on the battery terminals or the altenator to see if either is mysteriously low?

Good point, im going to do that right now...

 

[Defconx3 10+ year member]

Yep, checked the battery and the alt and they are both going strong at ~14v. I guess it has to be in the wiring somewhere. How mysteriously ghey.

 

[negativezeroz 5,000+ posts]

The 1500D has to be drawing a lot then. I doubt the Profile pulls more than like 25A. But ~7volt...****.

 

[bjfish11 5,000+ posts]

duh....all you need is a cap.....

 

[Defconx3 10+ year member]

The 1500D has to be drawing a lot then. I doubt the Profile pulls more than like 25A. But ~7volt...****.

No, you do not understand the situation all the way, I have the 1500d disconnected and it is still dropping to ~7v. It must be the wiring, but im stumped because I have had it working perfectly fine before with the same exact wiring and setup.

 

[Defconx3 10+ year member]

duh....all you need is a cap.....

How many will $4,289.00 get me! //content.invisioncic.com/y282845/emoticons/veryhappy.gif.fec4fed33b4a1279cf10bdd45a039dae.gif

 

[negativezeroz 5,000+ posts]

No, you do not understand the situation all the way, I have the 1500d disconnected and it is still dropping to ~7v. It must be the wiring, but im stumped because I have had it working perfectly fine before with the same exact wiring and setup.

Ohh! Gotcha now. //content.invisioncic.com/y282845/emoticons/blush.gif.99bc659ee2012b7d826165e26fb5eebe.gif ok where are you reading the 7v? At amp or directly from the alt/battery?

 

[PhatTonyDeMarco 5,000+ posts]

Maybe you have a pair of speakers wired wrong and have the wrong impedance for the amp than you want, causing high current draw?

What exactly has changed since you disconnected the Directed? You added the Profile amp?

 

[Defconx3 10+ year member]

Ohh! Gotcha now. //content.invisioncic.com/y282845/emoticons/blush.gif.99bc659ee2012b7d826165e26fb5eebe.gif ok where are you reading the 7v? At amp or directly from the alt/battery?

This is how things currently stand with the headunit on and the profile trying to play:

Volts at Battery and alt: ~14V

Volts at profile positive/ground terminals: ~7v when powered on, 14v when not powered on.