New Alt Still voltage drops!

[Anonymous 10+ year member]

I just got my Iraggi 220A alt installed with the pulley that came on it and when playing my system at my max volume(60/80) the voltage on my cap still only reads 10-10.5 and after about 30 seconds my battery light comes on. I have 2 Viper 1200's and a Viper 200.4. Along with the alt i have an Exide/Rockford 1100A batt under the hood the big 3 is done in 2/0awg and i have a 1 farad cap. The mechanic that put it in said that the alt was working fine, he said that it was reading 13.9v at idle, i doubt they were playing any music, and the only way i can measure the voltage is with what my cap reads and the fact that my battery light is coming on. What could be the problem and how could i fix it? I have been trying to get in touch with Iraggi to see wtf the deal is. But please help

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[937DYTBOI 5,000+ posts]

i would add a battery seriously ur killing that one battery up front, that 1 farad cap is not enough for what ur running

 

[Anonymous 10+ year member]

Why would i add another battery if it is not charging the one i got? If my batt light is coming on than it is not producing enough because when i turn it down the light goes off. Someone tell me i am wrong because i do not know **** when it comes to this

 

[MadAudio 10+ year member]

Why would i add another battery if it is not charging the one i got? If my batt light is coming on than it is not producing enough because when i turn it down the light goes off. Someone tell me i am wrong because i do not know **** when it comes to this

first off is the voltage drop happening while the car is in idle?

if it is then thats normal most high out alts dont put out rated till higher rpms

second hmm 13.9 is kind of low for a alt i think. should be 14.2 or better might need to change the pully.

the reason why the battery was suggested is your car battery acts as a buffer juice goes from alt to bat to system the greater your battery ability to maintain a 12v drain the less voltage drop you will have from the drain that 13.9 charge might indicate a low charged bat ( needs to be charged) , bad battery or loose belt .try it again only this time when the light comes on rev the engine a little say 1500-2000 rpm see if the light goes away then you know it has something to do with the alt's rpm either loose belt or you need to change pulley

 

[RandyJ 10+ year member]

As mentioned, a higher output alternator does notmagically put out it's rated power at idle, unless specifically mentioned. YOu are probably getting about the same at idle as your old alternator.

 

[mikeyboc 10+ year member]

What car is it in?

 

[Anonymous 10+ year member]

The alt i ordered was supposedly designed with a custom overdrive pulley to provide more at idle so i changed the belts out to fit properly so it should not be that. I do not know about my batt. I do not drive or start the car a lot so it might not be charged good.

 

[Anonymous 10+ year member]

2004 Durango

 

[helotaxi 5,000+ posts]

The battery light is telling you that you battery is discharging. Adding another battery will make it worse. First get rid of the cap, it isn't helping things. Next, get the alt tested under load. If the alt is putting out good volts under load then you have bad connection somewhere in the power chain. Check ever power and ground connection in the system. It could also be that you just don't have a good ground point for your system and are losing voltage there.

 

[Anonymous 10+ year member]

Where would test the alt under a load?

 

[helotaxi 5,000+ posts]

second hmm 13.9 is kind of low for a alt i think. should be 14.2 or better might need to change the pully.

Depends on the car. Some ECUs regulate the alt to around 13.8V. As long as it is abover 12.5ish it should charge the battery.

reason why the battery was suggested is your car battery acts as a buffer juice goes from alt to bat to system the greater your battery ability to maintain a 12v drain the less voltage drop you will have from the drain that 13.9 charge might indicate a low charged bat ( needs to be charged)

turning off the system would allow the battery to be charged.

bad battery

Probably the most likely cause.

or loose belt

doubtful, he would hear the squeal and none of the other belt driven accessories would work right either.
I'm guessing either bad battery, or bad ground.

BTW, have you done the big 3 yet?

The alt shop should be able to test the alt with the system running.

 

[Anonymous 10+ year member]

yes big 3 is done to 2awg and i do not think it is the ground or power connections because if i had a bad connection my voltage would be dropping and spiking without me bumping my system wouldn't it?

 

[QtrHorse 10+ year member]

Answer these questions.

What is the voltage at idle w/ out your system on?

What is the voltage at idle w/ your system on?

Is the lower voltage that you listed, while the car was at idle or at cruising speed and w/ or w/ out your system on?

My guess would be a bad battery as well. If you ran you battery down low, the alternator will never really fully charge it. You need to have the battery tested and if it tests good, have them trickle charge it overnight. A dirty or bad ground can make a world of difference as well. A cap will put a lot of strain on your battery. The cap has to fully charge everytime it is drained and it will draw from the battery.

Almost any autoparts should be able to test your alternator under load and they will do it for free while it's still in the vehicle.

 

[Anonymous 10+ year member]

My cap reads 13.5-14 with my system turned down at idle. When i turn my system up to my max volume(60/80 on the cd player it drops to 10-10.5v at idle

 

[Anonymous 10+ year member]

Alright i am going to get my batt and alt tested tomorrow. First of all what do u mean by getting the alt tested under a load? And what kind of results am i looking for at of this test, what would be good results and what would be bad results? And know they will tell me if the batt is bad so i just need to know those things.