Weird Alternator Charge Question

[Gone_2022]

Ok so just a few mins ago I went out to the garage to start the Trans am and just warm it up let it idle and things especially with this cold weather. The car sits in the garage on a battery tender at all times. I fired it up and the gauge for the alt charge almost hit 18 volts and has stayed there for a while until the car warmed up and then it moved back down to normal. I know the battery is fine since the tender keeps it at the right voltage. But why do GM cars do this and specifically F Bodies? My last Camaro SS did the same thing. Is something wrong? anyone else have this? Much help needed

Click to read more...

 

[skeezer]

MAYBE IT HAS TOO MUCH POWER

 

[Turbocharged400sbc]

:stupid:

 

[Gone_2022]

MAYBE IT HAS TOO MUCH POWER

Only does it when it's cold out or if it hasn't been started in a long time

 

[skeezer]

If it's constantly on the charger, then I would imagine your battery isn't lacking at all.

 

[Gone_2022]

I wouldn't think so I mean the light is green and the tender is working. Same thing happened with the Camaro SS I don't get it. Soon as it turned over bam shot up to almost 18 volts and I could hear the alternator for a real short bit. I'll have to look into it. I know the Cruze maxes at 15.5 but that's the highest I've seen

 

[bikrboy128]

measure battery voltage with the tender on, then while the car is running. your tender is probably overcharging it

 

[SRT41320]

i would suspect the tender is overcharging too

 

[Gone_2022]

I took the tender off before I started it. I'll try measuring it at the terminals next time I start it

 

[deviantlx]

It's common on gms for the regulator to stick for a few seconds before it starts regulating voltage. Just keep an eye on it. A few seconds isn't going to wreck anything but driving around at 18 all the time will.

 

[Gone_2022]

Alright thanks. It drops after a short bit. Was just the first time I saw it go that high and I knew that battery wasn't low.

 

[DynaSlim]

My battery new only starts the car when warm. Just had a problem today. Had to warm it up in the house and tested the alternator is giving me 15 when running. 03 Buick century.