Voltage dropping at amp terminals

[brandonio21]

Hi all,

I have a Sony xplod 1000W 2 channel amp, and it has worked perfectly fine with my 2 kicker 15 comp subs for almost 2 years. Last week, my alternator died, and so I replaced it and purchased a new and bigger battery for my car. However since this happened, my subs would randomly cut out, so I bought new wires and a new RCA cable and replaced everything. They still cut out and now they wont even hit, at all. I don't know whats wrong. I checked the voltage at the battery with the car on and off, and its good both ways. I also checked all my fuses for resistance and continuity, and they are all good. I then went to check the voltage going to the amp to see if it was just underpowering the subs now, and low and behold the voltage read around 5.4 volts. This was weird so i took the wires out of the amp and tested them and they tested good at 12.2 volts. Does anyone know why my voltage is dropping. It only happens when I screw the wires into the terminals on the amp. The inline fuses on the 4 gauge power wire are also ok. I checked them as well. Any help would be GREATLY appreciated!!!!

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[NASTY08IMPALA 5,000+ posts]

Hi all, I have a Sony xplod 1000W 2 channel amp, and it has worked perfectly fine with my 2 kicker 15 comp subs for almost 2 years. Last week, my alternator died, and so I replaced it and purchased a new and bigger battery for my car. However since this happened, my subs would randomly cut out, so I bought new wires and a new RCA cable and replaced everything. They still cut out and now they wont even hit, at all. I don't know whats wrong. I checked the voltage at the battery with the car on and off, and its good both ways. I also checked all my fuses for resistance and continuity, and they are all good. I then went to check the voltage going to the amp to see if it was just underpowering the subs now, and low and behold the voltage read around 5.4 volts. This was weird so i took the wires out of the amp and tested them and they tested good at 12.2 volts. Does anyone know why my voltage is dropping. It only happens when I screw the wires into the terminals on the amp. The inline fuses on the 4 gauge power wire are also ok. I checked them as well. Any help would be GREATLY appreciated!!!!

That amp is more than likely trash..with voltage that low at the inputs...the old alt might have been spiking to a high voltage before it went out amd shorted the amp ..time for a new sub amp

 

[brandonio21]

That is what I thought, so I went to a buddy's of mines house, and I hooked my subs up to his amp, and they made some noise but the voltmeter was still only reading about 7.4 volts at a high when I put the voltmeter on the terminals. If the alternator did spike though, wouldn't i have noticed power loss at other places in my car as well?

 

[NASTY08IMPALA 5,000+ posts]

That is what I thought, so I went to a buddy's of mines house, and I hooked my subs up to his amp, and they made some noise but the voltmeter was still only reading about 7.4 volts at a high when I put the voltmeter on the terminals. If the alternator did spike though, wouldn't i have noticed power loss at other places in my car as well?

So his amp in ur car only read 7.4 ? Are you sure the battery in ur meter is good? Check the battery and alt up front and check the power wire right before amd after any fuse blocks to see where the voltage is dropping. Very odd

 

[dbjunior 10+ year member]

What terminals are you trying to read power or output?

 

[NASTY08IMPALA 5,000+ posts]

What terminals are you trying to read power or output?

Im pretty sure he said power bc he said he pulled power from amp and checked bare wires

 

[brandonio21]

nasty08impala is correct, i pulled the power and ground and checked the bare wires directly. and as for where the power is dropping, I checked the inline fuse and the voltage across it directly before and after is 12.4 to 12.2-12.3. the voltage before and after the fuse block only changed by about .1 volts. I honestly am not sure where the power is dropping. :/ And as for the battery and alternator up front, with the car off measure 12.1 volts, and with the car on measure 13.4-13.6 volts, which i believe is good.

 

[NASTY08IMPALA 5,000+ posts]

nasty08impala is correct, i pulled the power and ground and checked the bare wires directly. and as for where the power is dropping, I checked the inline fuse and the voltage across it directly before and after is 12.4 to 12.2-12.3. the voltage before and after the fuse block only changed by about .1 volts. I honestly am not sure where the power is dropping. :/ And as for the battery and alternator up front, with the car off measure 12.1 volts, and with the car on measure 13.4-13.6 volts, which i believe is good.

Yea thats all ok ..but the fact that ur getting 5 and 7 volts with 2 diff amps is fishy

 

[brandonio21]

yeah, i dont know why that is happening :/

 

[brandonio21]

My friend's dad has done a decent amount with electricity and he thinks i may have fried one of the voltage regulators in my car...Is that a possibility?

 

[NASTY08IMPALA 5,000+ posts]

My friend's dad has done a decent amount with electricity and he thinks i may have fried one of the voltage regulators in my car...Is that a possibility?

I wouldnt think so esp if ur getting a solid constant 12v from the wire and ur new alt would rule out a voltage regulation problen i would think

 

---------- Post added at 09:57 PM ---------- Previous post was at 09:56 PM ----------

 

The voltage regulator is in the alt

 

[brandonio21]

So is there just a short or something in the car wiring somewhere?

 

[brandonio21]

Also, i failed to mention that i had my alternator rebuild because it was substantially cheaper and i am very good friends with the individual who rebuilt it. Would the alternator still work even if the voltage regulator was bad?

 

[NASTY08IMPALA 5,000+ posts]

So is there just a short or something in the car wiring somewhere?

Yea could be but very odd to get solid voltage right outside the amp at the wires then getting such low voltage at the amp

 

[NASTY08IMPALA 5,000+ posts]

Also, i failed to mention that i had my alternator rebuild because it was substantially cheaper and i am very good friends with the individual who rebuilt it. Would the alternator still work even if the voltage regulator was bad?

Yea it will still work but if he didnt replace the voltage regulator then it could be spiking or dipping ..you can have it load tested at autozone or another parts store

 

[brandonio21]

I went to autozone today, and they tested the battery and stuff and said that my battery is being fully charged but that the battery has dead cells. I thought this was weird because the battery is not even a week old.

 

[NASTY08IMPALA 5,000+ posts]

I went to autozone today, and they tested the battery and stuff and said that my battery is being fully charged but that the battery has dead cells. I thought this was weird because the battery is not even a week old.

Get the battery replaced then have them load test the alt ..they wont test the alt when the batt is bad

 

[brandonio21]

Ah, ok! that makes sense! thanks! if they load test it and its bad, what should i do? would buying a bigger alternator be a good idea, or should i buy a second battery and parallel wire it?

 

[Nutdawg651]

Ah, ok! that makes sense! thanks! if they load test it and its bad, what should i do? would buying a bigger alternator be a good idea, or should i buy a second battery and parallel wire it?

Id take the alt back to your good friend and ask why he didnt replace the regulator and have him replace it free for ****** up

 

[NASTY08IMPALA 5,000+ posts]

Ah, ok! that makes sense! thanks! if they load test it and its bad, what should i do? would buying a bigger alternator be a good idea, or should i buy a second battery and parallel wire it?

Id get a new alt...going with a ho alt is up to you . If you plan on upgrading over 2000rms in the near future id say go for it ..but if not a stock alt will be fine ..and as far as the 2nd battery ..really wont be needed unless u cross that 2k mark..just replace the battery under the hood with a good agm battery