Hey all,

I think my altenator is hating me. Basically here is how it goes. I will start my car and the on-dash volt meter will be pointing over he 13 mark. After about 20 minutes of driving with my stereo at a good level "not cranked wide open" the volt meter will start to drop and rest pretty much at the 13v mark. I am running a stock altenator in the car with a new RedTop Optima battery that is belting out 1125cca.

Now I think my alt might be going but I can't be sure. I want to upgrade to a Powermaster 145amp altenator. Would upgrading to the higher output alt allow me to push my stereo harder without having my lights dim and that needle drop?

 

simply put: yes

Ur stock alternator isnt charging the battery fast enough to make up for the pull from the stereo. I have a 140amp alternator in mine and i have no problems

 

Well I took your advice. I ordered a powermaster 140amp chrome alternator. Baby is setting me back $300 but the chrome sexiness is so worth it.

 

How many amps does it put out below 2,000 RPM?

That's the thing with GM alternators. Below ~1,500-2,000 RPM they don't "charge" the battery unless it needs it. As long as there is more than 12.5 volts it leaves the battery alone.

 

Hmm I didn't know they made Red Tops that big... largest I've seen is 750ish CCA range. Even the big D31 Optima are only around 950 CCA rated, supposely the do more.

Here's a link I found on another forum that talked about a 140 powermaster output. http://pub209.ezboard.com/famcforumf...picID=32.topic

"It puts out 82 AMPS at 800 RPM! and 142 at 3000!" So if the pulley ratio is about the same you should see similar results.


Make sure you upgrade the line too from the alternator to battery. Here's a CarCraft article on it (also includes a wiring size/distance chart).

http://www.carcraft.com/techarticles/85610/index3.html

They also went on to say: "Powermaster recommends limiting alternator speed to a maximum of 18,000 rpm. With a pulley ratio in the 3:1 range, you could easily exceed this speed in a drag car that frequently sees 6,000 rpm at the track."

"Powermaster rates its alternators idle output at a 2,400-rpm “alternator” idle"

Here's the link to the pulley ratio article: http://www.carcraft.com/techarticles/85610/index2.html

 

Well when Wally world tested the bat it came back 1125cca. It says 925 on it. Its a good battery none the less.

As for the alternator...I upgraded the magic 3 a long time ago. Boomin Boy said it enough in these posts so it kinda sunk in and made me do the upgrade. Hopefully this alt fixes the power issues.

 

You should test your voltage level with a DVM as the stock gauges are rarley ever right. Mine always shows under 13 volts (usually 12) but it is actully staying around 13.9-14.2 volts.