Print Page | Close Window

test alternator output?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=98858
Printed Date: March 28, 2024 at 8:24 PM


Topic: test alternator output?

Posted By: ice32
Subject: test alternator output?
Date Posted: November 10, 2007 at 8:15 PM

Hey,

Is there anyway to test the output of a alternator, to see if it will still have enough power to charge a sound system?

Thanks



Replies:

Posted By: stang351w
Date Posted: November 13, 2007 at 8:12 PM

Is there anyway to test the output of a alternator, to see if it will still have enough power to charge a sound system?

Thanks

well, first off, the alternator doesn't charge the sound system. it charges the battery which provides power to youe stereo. depending on what kind of power your running for your system would determine what you need to do, if it's just a small amplifier that only have 40 amp of fuseing, don't worry to much, but if your drawing 100+ amps to run your system then you need to consider some upgrades. if you have any doubt read up on upgradeing the "big 3" (stickyed at the top of this forum i beleive) and maybe upgrade to a ultima yellow top or some other deep cycle battery that would work in your aplication.



-------------
Tri County KustomZ
certified installer




Posted By: zhalverson
Date Posted: November 15, 2007 at 10:41 PM
stang351w wrote:

well, first off, the alternator doesn't charge the sound system. it charges the battery which provides power to youe stereo. depending on what kind of power your running for your system would determine what you need to do, if it's just a small amplifier that only have 40 amp of fuseing, don't worry to much, but if your drawing 100+ amps to run your system then you need to consider some upgrades. if you have any doubt read up on upgradeing the "big 3" (stickyed at the top of this forum i beleive) and maybe upgrade to a ultima yellow top or some other deep cycle battery that would work in your aplication.


Well that's actually not true either.  When the alternator is working it would be charging the battery and providing current to your stereo.  The alternator will be operating at roughly 14 volts and that's what your amps will be operating at while the battery is only 12 volts.  This means your amps will be getting their power from the alternator and not the battery.  The only time the amps get their power from their amps is when the car is off or the voltage dips below 12 volts.





Posted By: jmelton86
Date Posted: November 16, 2007 at 12:02 AM

Can you simply hookup a DMM set to 'DC voltage' and rev the motor to see what amperage it peaks at (accesories off, of course)?

I actually always wondered this, just didn't think so since I haven't seen anything about it before.



-------------
2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001




Posted By: i am an idiot
Date Posted: November 16, 2007 at 5:01 AM

Morning J   You can use a DMM on the voltage scale to see if the alternator is putting out Voltage.  To get the output current of the alternator it is a little more complicated.  That requires a clamp on DC current meter and a battery load tester.  Any reputable alternator shop will have the equipment needed.   Clamp the meter around the charge wire and connect the load tester to the battery.  When the load tester pulls the battery down the alternator will do its best to get the voltage back up to 13.8 thus producing all of the current it can.    

If you are using a DMM on the voltage scale, it is better to turn everything on, Lights, Air Conditioner, Stereo System Etc.   With all accessories on you will be demanding the most out of the alternator.  If it is able to increase the voltage when the motor is rev ved slightly, this ONLY means your alternator is working.  It will not tell you how much current it is putting out.





Posted By: ice32
Date Posted: November 16, 2007 at 9:01 AM
so if at a little above idle revs your alternator can still increase the volts.

it means that the alternator is doing its job with the current set up?

I'm just getting a terrible wine out of my alternator when i rev up and down, im thinking it is that i am drawing to much,

My dads a old mechanic and thinks it just needs a bigger compressor on it as he put a small one on it but it didn't do much (people didn't have "boom box's" in the boot in his day, so he dosn't believe its over drawing) but we will try that some time soon.

my system has 110A of fuse's but probably isn't drawing anywhere near that much at operating levels

and the alternator is 90A

Maybe a big 3 upgrade and a new battery is in order?




Posted By: jmelton86
Date Posted: November 17, 2007 at 3:14 PM

i am an idiot wrote:

Morning J   You can use a DMM on the voltage scale to see if the alternator is putting out Voltage.  To get the output current of the alternator it is a little more complicated.  That requires a clamp on DC current meter and a battery load tester.  Any reputable alternator shop will have the equipment needed.   Clamp the meter around the charge wire and connect the load tester to the battery.  When the load tester pulls the battery down the alternator will do its best to get the voltage back up to 13.8 thus producing all of the current it can.    

If you are using a DMM on the voltage scale, it is better to turn everything on, Lights, Air Conditioner, Stereo System Etc.   With all accessories on you will be demanding the most out of the alternator.  If it is able to increase the voltage when the motor is rev ved slightly, this ONLY means your alternator is working.  It will not tell you how much current it is putting out.


Sweet. I work at a Napa attached to the side of a Carmax (we supply their parts) so I have access to the stuff. I'm actually on 'vacation' until Tuesday after next (weee!) so it won't be until then. Thanks.

ice32] wrote:

'm just getting a terrible wine out of my alternator when i rev up and down, im thinking it is that i am drawing to much,

my system has 110A of fuse's but probably isn't drawing anywhere near that much at operating levels

and the alternator is 90A

Maybe a big 3 upgrade and a new battery is in order?

Big3, for sure. I think you're in the same boat as me. I've got 95a max system power (plus an extra Yellowtop) being powered by my stocker 105a alt and have been burdened by the dreaded 'whine' so I think i'm'a have to replace it. I do need to try one other thing first, though (outer sheild solder joint in my amp, thanks again- i am an idiot).



-------------
2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001




Posted By: i am an idiot
Date Posted: November 17, 2007 at 4:15 PM
Hey Ice let me guess,  A Pioneer radio?




Posted By: ice32
Date Posted: November 17, 2007 at 6:31 PM
you got it, I've read about there earth problem, should i try earth the rca and see if the whine goes away?




Posted By: i am an idiot
Date Posted: November 17, 2007 at 7:04 PM
I would.   It will go away.




Posted By: ice32
Date Posted: November 17, 2007 at 7:27 PM
hmm, righto, i'll give it a shot, but im not optimistic seems i just put some cheap head unit in my buddys ford falcon and it has the same whine.




Posted By: jmelton86
Date Posted: November 22, 2007 at 1:57 PM

Update; I resoldered the RCA negatives to the amps' board. Noise is still here. I think I may need an alternator replacement... Yay.



-------------
2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001




Posted By: i am an idiot
Date Posted: November 22, 2007 at 8:45 PM




Posted By: jmelton86
Date Posted: November 27, 2007 at 6:14 PM

[QUOTE=i am an idiot] https://www.bcot1.com/images/rca/temporaryrcashieldrepair.html [/QUOTE]

Great, great link. Thanks. I've actually tried grounding the RCA negatives and it made the noise get way worse! I did it at the amp end if it makes a difference...

I guess I just need to check resistance between the HU case and RCA negative, with the RCA's unplugged. Correct?

BTW, that link should be in a dedicated sticky on temporary Pioneer noise repair!!posted_image



-------------
2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001





Print Page | Close Window