I am having issues with my Cherokee, i am getting the low voltage light and my battery gauge drops to 9, the lights will dim and the radio will turn off. I had the car idling and tested the battery and it was reading around 9v when i would turn the lights on and turn up the heat it would drop even further. I manage to make it home where it would not longer start once i turned it off. I currently have it on a battery charger.

What i have done so far:
Battery tested (twice) and is good.
Alternator was removed and brought to the store and tested and is also good.
I replaced the ground cables about 9 months ago and are good. I replaced the cable from the battery to the frame, from the engine block to the firewall and one other one i can think of off the top of my head. I also replaced the rest of main electrical cables at that time,
I replaced the Engine control module with a certified refurbished one from flagship one.
I cleaned out the electrical connectors to the alternator and ECM with CRC electrical contact cleaner.
Both battery terminals are new and clean no build up anywhere on the battery.

I read on this site someone had mentioned that the distributor and rotor could be an issue, i am not sure why this would be the culprit but i have not changed that yet. The issue is real and is not just a gauge issue but i am out of ideas. Any assistance is appreciated.

Thanks,
Josh