Voltage problem!

[TheFiverMan 10+ year member]

I got a 2007 impala. Done the big 3 got a 270 amp alt and a brand new yellow top. When i start the car its at 14.3-14.5. then when i take off and turn up my head unit it goes down to about 13.2-13.5 and stays around there. i dunno if this is normal or not. After about 10 minutes of driving my "Battery Saver Active" light comes on. When i read the voltage up front its right at 14v but on the stinger gauge in my car it says mid to low 13s. Any suggestions?

Click to read more...

 

[KidThump 10+ year member]

Maybe get a battery for the back as well, idk if that is the problem or if it even could be, just an idea.....

 

[Omg Itz Layz 10+ year member]

you have the power line off the voltmeter wired to the power line on the head unit i did the same once wire the red wire to the battery pos

 

[goingdef 10+ year member]

Other then slightly odd readings between the gauges is it causing any problems? a lot of the newer cars are so computer controlled(drive by wire)that constant changes in the cars voltage causes the computers to function oddly if it's not causing any malfunctions in the car I would just go with it on the other hand if it's causing issues then I would figure out a way to isolate the stereo system some way maybe re-install the factory alt to strictly run the car and have a custom bracket made for the high output alt and have it only power the stereo system (kinda a b*tch but possible)

 

[Slo_Ride 5,000+ posts]

Other then slightly odd readings between the gauges is it causing any problems? a lot of the newer cars are so computer controlled(drive by wire)that constant changes in the cars voltage causes the computers to function oddly if it's not causing any malfunctions in the car I would just go with it on the other hand if it's causing issues then I would figure out a way to isolate the stereo system some way maybe re-install the factory alt to strictly run the car and have a custom bracket made for the high output alt and have it only power the stereo system (kinda a b*tch but possible)

This. You need to recheck EVERYTHING you did. Everything is comp controlled these days, has anything else (fuel economy, power, stalling, windows slower, lights dimmer, etc.) changed? The light is on for a reason.

 

[TheFiverMan 10+ year member]

Everything is fine. just the AC will go off and ill have to turn it back on. But i read up on that battery saver active light and it says it will do that when the voltage is low. which isnt possible because its 14v all time up front. Unless its the alt. Might be just something in the computer causing it since this is alot bigger alt.

And to Omg Itz Layz your right. So i think thats my problem with the gauge because up front wasnt dropping below 14.

 

[keep_hope_alive Premium Member]

what vehicle?

as mentioned, some cars will reduce the alt output when the car's ignition system is not drawing a lot of load (EX: Honda Electronic Load Detector). Turning on the A/C will increase the load on the ignition system, thus the car's ECM/PCM tells the alt to increase output.

just dropping in a H.O. alt without understanding how the field is controlled can cause issues.

if the voltage at the battery is much higher than the voltage at the amps - you have a voltage drop issue on your power wire. this is caused when the power wire is too small or the amp grounds are poor. where/how are the amps grounded?

 

[TheFiverMan 10+ year member]

It's a 2007 impala. I don't have an amp hooked up. Just my head unit. I think it's how I got the voltage gauge wired. Because up front it reads 14 volts.

 

[keep_hope_alive Premium Member]

the ground for the volt meter is equally important for an accurate reading.