Battery not getting charged

A couple of weeks ago hopped in the jeep for a weekend ride and battery was about dead. Got jumped and went to local auto parts store. They checked battery said it was fine. Took off the alternator, had it bench tested, they said it was not delivering stator voltage and needed to be replaced. Got the new one in today and still having the same issue. When I go to crank she's very sluggish to turn and then dead. Jumped her off again, started right up and ran around for about 30 minutes thinking that would charge battery. Voltage meter shows 14 volts while running but does drop down to about 8 at idle. When I turn the key off and then try to crank the volt gauge drops to 2 and is not enough to crank.
Once again, battery is good. Had it on charger these last 2 weeks and was on automatic float anytime I looked.
F134 engine 1967 cj5
Ideas? Thanks

 

Battery cables and connections, at both ends including ground, all clean and tight?

 

at idle it needs to be around 14 volts or so. internal regulator one wire alternator?

 

Battery connections all clean and tight.
Its a one wire alternator with internal voltage regulator, Remy-delco. Same model as the one I replaced.

Im beginning to wonder if the battery test done by auto parts store really valid......

 

in a battery a plate can short out with the build up of the lead sulfide. it can read fine voltage wise but not carry the amps to do much. the alternator is also not putting out the voltage required at idle. I would either get a rebuild for the regulator or just get a replacement alternator in its entirety, again.

 

Get a hydrometer (they are cheap) and check the specific gravity after the battery has been sitting for a few days. One bad cell can cause the same symptoms. Make sure the alternator belt is tight. Not all volt meters are a reliable indicator of battery and/or charging conditions.

 

I have to agree with battery issue. What method did they use to test the battery? Was it load tested? Capacitance test? Was it done with a fully charged battery?

 

You can load test a battery with a volt meter which you are doing with the in dash one. A good battery shouldn't drop below 10 volts when cranking. Sometime OEM instruments are disconnected during cranking, so use a multimeter connected to the battery and have somebody else crank the jeep over while you are observing voltage drop.

Then use the meter to verify voltage at the battery while the jeep is running.