Charging system is no good, what to change and how?

[puppetz007]

Been trying to diagnose why my battery keeps losing its charge. I have a new battery and alternator (replaced with warranty). The voltage with the truck running is 12.22v which I know is no good. My question is what wires do I need to replace (if any) and how is that done? What fuses do I need to look at?

 

[jakknz]

Is there anything that's draining the power from the battery once you take the key out of the ignition? Your charging system more than likely is fine. You probably have a power drain somewhere. Have you done any work to the truck recently like adding an aftermarket radio?

 

[KidVermicious]

Puppetz, if the alternator and battery both test good, I'd check your grounds next. There's probably at least 3 - battery to engine, battery to body, and body to frame.

 

[STRRAYNGE]

When your vehicle is running, your alternator should be putting out between 13-14 volts,(ideally between 13.8 and 14.2 volts) to effectively charge a 12v car battery. Im sorry, but 12.22 volts is still too low, unless you are taking that reading with the engine stopped. Im not sure what the issue is, but I would get it checked out again somewhere.

 

[LDForget]

sounds like the cable going from your alternator to the battery has a poor connection somewhere. Start the vehicle and grab a multimeter and put it on v20 mode with the black wire on common and the red wire on V or Voltage side. first put the black on the case of the alternator and the red on the large wire coming out of the alternator. it "should" read about 14.6 Volts. Next, measure the battery's voltage potential to make sure its the same as your last reading, around 12.22 volts. If this is still the case, put the black on the alternators large cable (power out) and the red on the batteries positive terminal. If you get anything more than .05 volts, thats your problem. Try putting a booster cable going from the alternators positive post to your batteries positive post to confirm your findings. you should now have 14.6 volts at the battery. If this is indeed your issue, just go to your local car audio shop and ask for a few feet of 8 or 4 awg red wire and a couple terminals to make a new alternator power wire.

 

[LDForget]

any update on this?

 

[Drcoffee]

Puppetz, if the alternator and battery both test good, I'd check your grounds next. There's probably at least 3 - battery to engine, battery to body, and body to frame.

All too often the Black ground lead is faulty. If the old battery had acid leaking at the posts, it migrates down the cable under the plastic sheath. Install a new battery ground wire and it should work again. While you are at, check all the frame ground points. Remove the bolt, clean the contact point and reattach with dielectric grease.

 

[Baja Runner]

Just having battery drain issues myself. Replaced starter contacts and its been better. Not sure this is your problem, but just throwing that out there.

 

[puppetz007]

Sorry guys I've been moving all weekend and haven't been able to get on and check everything. As it sits now I'm still getting around 12.4 Volts when the engine is running. I did notice some corrosion on the connector that plugs into the back of the alternator. I think that could be causing the problem. Anyone know if this is a common problem? Also, does anyone happen to know the part number for that wire?

 

[puppetz007]

Bump. Any ideas? I think I'm going to unbolt the fuse box so I can get a look at the wiring that goes into it. Correct me if I'm wrong, but as far as I understand the wire from the alternator goes into the fuse box then to battery positive?

 

[LDForget]

did you do the tests i instructed?

 

[puppetz007]

I haven't put the booster cable on yet. Was going to get to do it yesterday, but got stuck at work late.

 

[LDForget]

whats your voltage at the alternator?

 

[puppetz007]

The voltage at the alternator is only 11.42, which I'm guessing means the alternator is no good and needs to be replaced again. With the MM black on the alternator power out and the MM red on battery positive I get a reading of 0.16 volts. Thoughts?

 

[LDForget]

The voltage at the alternator is only 11.42, which I'm guessing means the alternator is no good and needs to be replaced again. With the MM black on the alternator power out and the MM red on battery positive I get a reading of 0.16 volts. Thoughts?

That means your losing .16 volts from the alternator to the battery, not that big of a deal really. Id say your alternator is shot. probably just the regulator inside the alternator...but most people dont bother rebuilding them anymore.