Hiya, this is my first post. I have a 2000 Chevy Blazer LT 4.3, and I've been having the problem when it sits for a couple of days the battery is dead..... I'm trying a few things I saw in other posts on this problem... charged the battery,put in a new Alt. and serpintine belt, removed the rubber ends from the cables and cleaned everything really well. the Pos. cable wasn't corroded, but it was kinda dirty... the grounds were all good. now my standing volts are" 12.53
Running volts are at :14.83-15.00 And the parasitic draw was at :0.00ma...I'll keep ya updated if this fixed the problem since there seems to be alot of this type of problem with chevys.....

 

Sounds like battery. Take it and see what the cold cranking amps are. How old is battery. Betting CCA are LOW

 

Regulated voltage should be 14.2 volts. 14.83 to 15.0 is much too high and will destroy the battery prematurely. Probably a bad voltage regulator in the alternator, or a poor ground, (high resistance).

Parasitic draw should not show zero. There are several memories onboard that continuously draw current, and parasitic draw varies from vehicle to vehicle. All current must pass through the DVOM while testing, if not, it will indicate zero draw. After disconnecting the positive battery cable, memories must be initiated with an external voltage source. They must be kept alive while connecting the DVOM in series between the positive battery cable, and the positive battery post, then remove the external voltage source.

 

The battery was replaced on 9/15...LOL it looks like I still have some detective work to do.
the alt. and serp. belt were replaced about 2/23/16. So far, everything seems good.....But we know how that goes.....I'll keep ya updated.....Thanks for the info.....

 

An open cell in the battery will cause regulated voltage to rise, and the inability to hold a charge. If regulated voltage is too high with a good battery, the regulator could be the cause of the battery failing. The alternator, voltage regulator, and the battery, are a system, and they all need to play nice together . Prior to 1998, the voltage regulator on these trucks was powered by the ignition circuit. On your 2000, it is controlled by the PCM, which changes how the system performs, and how it is diagnosed.

 

Thx. Captain Hook..... So far all seems ok, but i think i may have a bad tensioner or pully.
after running for a few min. she gets to squallin.....was quickly running outta daylight..lol
If I get a chance I'm gonna check it out to see whats going on.... thx for the info.....

 

OK, I finally got a chance to look at this problem closer.....I went out and the truck fired right up, I popped the hood and checked the voltage at the battery and it was kicking out 14.67 volts. everything looked good. i ran it for about 10 min. and shut it off to run inside. when I went out and started it again, the bat. light came on and the voltage gauge read about 10 volts or so... So it seems like once it warms up, it starts acting up..... Would thios be a bad alt. or maybe the PCM ??? The grounds are good, fairly new battery,new alt. and belt.....

 

On the rear of the alternator there should be one 10ga red wire attached to a stud with a nut, and a rubber boot over it. It must show battery voltage at all times. On the right side of the alternator, toward the rear, there is a smaller connector, how many wires, and what color, are in that connector?

 

The voltage at both the battery and the 10 gage were 11.67 volts while running. and the plug connector has 1 Red wire on it.....

 

Voltage is a little low, but shouldn't make the light come on. With the key in the RUN position, engine off, what is the voltage on the small red wire?