20 volts at battery and alternator.....?

[pistolPJ]

Kind of strange. i noticed this today while looking at the very low ammeter/battery gauge in the car. So i decided to break out the multimeter and was suprised to see those readings. I did clean the battery terminals extensively as there was some decent corrosion on the (+) and a little on the (-). This didnt seem to do anything at all. Here is the rundown:
Initially i got about 17v at the battery with the car off and a crazy 44v at the alternator but soon went down to around 20v

I cleaned the posts and then retested and got the same...with the truck idling i got ~20 at the battery and ~21 at the alternator.

I figure the voltage regulator may be busted but how does that explain the low low readings on the in-car gauge?

I put in a Paladium 130a alternator under a year ago...didnt replace any of the wire. The battery is relatively new and from what i saw is working fine.

Does anyone have a clue what this may be? Thanks for any help you guys can give!

oh...and i wasnt able to run it to 2000 rpm or load test it as i was alone and it was dark...thus i had to hold the flashlight like you would a phone haha

 

[BrooklynBay]

Are you using your meter in the proper setting? Is it an analog, or digital meter? Do you have another meter to compare the test results?

 

[aldive]

Strange indeed.

 

[ProjectAviator]

Your voltage regulator is toast. If you are getting over 14.4 volts. that is a problem. At 20v that is seriously overcharging and can cause other damage.

Tim

 

[BrooklynBay]

He stated previously that his battery was showing 17 vdc with the engine off. That makes me think there might be a problem with the tester. They are usually 11.5-12.5 vdc with the engine off.

 

[Bill Kemp]

With that high of volts the battey should be boiling over.
I vote for a bad test meter also.

 

[pistolPJ]

yes i had thought that my meter was fried...i guess i could test on another vehicle or my bike. As far as the high voltage goes, if it were 20v i too was thinking that it would have destroyed that battery. So if the multimeter is NOT fried then we have a case of a fried regulator and a very lucky battery. If the multimeter IS fried, then i still have a possible ruined alternator...again. remember, the ammeter still reads low overall, but still responds to load, as in it raises with initial inc in rpms or i guess a response from the regulator when it senses a load like..say...the headlights. i know that i am not overtaxing my charging system assuming everything is working as it should. I am running a small amp and sub with a single 30a fuse.

So...the in-car battery gauge...ammeter...where does it take its measurement? Is it measuring voltage returning to it post alternator or is it measured near the beginning of the circuit? This is such a great forum and you guys know your stuff! thanks for the help on this!

 

[BrooklynBay]

An ammeter is in series with the circuit, and measures current. A voltmeter measures voltage on the ground (-), and (+) of the battery. The gauges are controlled by the the ignition switch, so nothing registers (completes the circuit) until the ignition switch is in the accessory position.