Took a drive to the store. Everything was normal then I saw the battery light come on real faint (almost barely noticeable.) So I shut everything off (radio, heater, Sirius, heated seat) and kept driving. The light went away for a bit came back then went away. Each time real real faint. Got home parked it cleaned the terminals Started it up idled it for a bit and then shut it off. This morning on my way to the mountain I had to jump it with my van to get it going (-12 degrees last night, thought that's what killed it) then drove it halfway to the mountain when the light came on again. (Still real faint flickering) (Also The windows moved really slow.) So I pulled over assuming it was the battery. Silly me was not thinking and Took off the negative terminal. Car died instantly and would not start. Got a jump and drove it directly home and put it in the garage. Then I charged the battery on 25amps and after it was charged started it up. Took the negative off and it bogged down but kept running. No battery light came on or anything.
The current battery in this car has been taxed allot lately and I'm wondering if the battery can be the soul cause of this or is the charging system to blame.
Can a bad battery cause this?
Bad cell perhaps?

Thanks in advance