Changed alternator, still not charging well

[Purduegmc]

I switched my alternator to an internally regulated 94 amp from the factory external. I was hoping to see some big changes. Well, I didn’t. It is charging at slightly over 13 volts (was 12.5). Should I probably be getting more? Is there a possible problem with the factory wires? I followed the FAQ by toddtheodd to convert to the internal. Anybody have any ideas?

[rage'nrat638]

13 sounds about right..

hook a meter up and check the output voltage..and see if the dash meter is correct..

turn everything on heater,blinkers,wipers,headlights,stereo

you will notice that the lights don't flicker at idle any more

mark

[Jerdog]

13 volts is too low. A fully charged lead acid battery is 2.2 volts per cell, 6 cells is 13.2 volts. Typically the alternator output is 14.0 to 14.4 depending on the current condition of the battery. What type of alternator are you using?

Jerry

[Longhorn Man]

use a miultimeter, and test the output on the post on the back of the Alt... I'll bet it's actually putting out 15 or so volts, but only 13 is making it to the battery.

[motopatzo]

The best way to check the charging system is with a load tester. Checking voltage gives you a ballpark number, but does not give you the amperage that the alternator is capable of producing when it is fully loaded. If you have a 70 amp alternator, it should produce close to that amperage when you have maximum load on the battery.

I think 13 volts is enough to charge the battery. Each cell is 2.1 volts and a fully charged battery is 12.6 volts. The lower voltage could be caused by a bad battery, or there is a load on the system while the truck is running (such as lights,defroster, heater, A/C, etc).

[truckdude239]

Originally Posted by Jerdog

13 volts is too low. A fully charged lead acid battery is 2.2 volts per cell, 6 cells is 13.2 volts. Typically the alternator output is 14.0 to 14.4 depending on the current condition of the battery. What type of alternator are you using?

Jerry

that is not true a fully charged battery should read betweeb 12.2-12.6 if i see a battery at work over 12.8 i have always seen the battery test bad

[Jerdog]

Purduegmc, Did you ever figure out what was wrong with your charging system?

Jerry

[Purduegmc]

I am still working on it. I am waiting for a load tester, and the fact that I am currently a couple of hours away from my truck right now. I got to looking at some of the 37 year old wire and well.... I am working on it maybe this weekend. I will let you guys know what I find. If anyone has any ideas, let me know.