Problem?

[4bogginchevys]

I was curious why the volt meter was riding a little high recently so this mornin' I checked output of the alt while the truck was warming up...on high idle. Driver alt was 15.0 flat...Pass alt was 14.9...for 29.9 total. The meter only lowers out of the red (toward correct voltage mark) when I run the lights at dark. The batts are only a yearf old/new cables/alt 2 is new a couple months ago/drive alt still works.... all connections are strong and secure, no corrosian. Come to think of it, it has been running high on the meter for atleast a month...I was kind of just waiting for something to fail so that I could replace it, nothing is failing to the point that I have any real trouble. What do all of you think? Thanks again

 

[charlietango]

seems a bit high to me. I can see it eventually boiling your batteries. When did you change the alt's last?
Mine runs up initially after having the starter load etc then drops itself back to just positive of center. If I run the fan or lights it will spike a min then settle back in. if I kill the engine, run some accessories for a while then start it back up it will run high until it charges back up then resume as above.

it could be a voltage regulator. My 69 charger always cooks the regulator and it does what your truck is doing.

 

[4bogginchevys]

maybe alt 1 is cooking alt 2 and batt 1 ?

 

[Keith_J]

maybe alt 1 is cooking alt 2 and batt 1 ?

Each alternator charges one 12 volt battery and each alternator is regulated to produce 13.8-14.2 volts. It does this by sensing the voltage off the battery it is to charge. If this voltage is lower than the actual battery voltage, you will get such overcharging. This sensing is done off the #2 terminal.

Each alternator operates independently, the wiring diagram in Appendix F9 of the -20 TM is incorrect in stating #2 alternator charges both batteries. This is confusion with the 200 amp charging system of the M1010.

 

[4bogginchevys]

I know they are independant, thanks for the response....it is possible that both regulaters are bad, or the batts?