Alternator charging problems?

Hi Brandon, I have the same exact problem you described. Did you find the problem yet? The mechanic here does not know a whole lot. Did you try taking it to a shop who has a real charging system tester like Autozone used to have? I am curious if the new alternator is actually putting out any amperage at all at this point. The voltages are good without the AC running but I do not know if any real amperage is getting to the battery to charge it. I was thinking something is grounding out somewhere once the cooling circuit is engaged. Please reply with any suggestions. Thanks.

It started with the surging of the headlights and blower fan motor. I then tested voltage at the battery while idling at 700 rpm voltage at 12.5. I then replaced the alternator because the battery was not very old. The new alternator did the exact same thing. At 1250 rpm with AC on and fan blowing on high voltage is at 14 volts. Same thing happens with rear window defroster (heavy load) at idle. Tested battery and was reading 10.5 volts. Replaced battery and continued to do the same thing. Without any load at idle it is at 14 volts. It seems under heavy electrical load at idle it cannot charge the battery. I replaced the ground wires and same thing still persists. The 100 amp fuse is good and the positive wire coming off the alternator is good as well. What could it be? Thanks.

Hello, thank you for your reply. I have replaced the block to battery and chassy to battery ground connection. They all meet at the negative battery post.

Even at 1000 rpm with AC on my voltage is around 13 or so. Not until around 1,300 does it get back to 14 volts. Thought maybe it was also running to low on the rpm's. With AC on its sits at 700.

My other thought was I burned out two alternators because the battery failed on the first maxing out the original alternator. Then I stick a brand new alternator in with a bad battery ruining it. Is this possibly too? Thanks for your help.

I have same problem I was wondering in you ever solved it or not. I tried all the same things my battery will die if I run my AC too long. I have brand new alternator and battery and upgraded all wires to zero gauge.