Hyundai accent 2003 with 76,000 miles Need Help!

I have a Hyundai Accent 2003 with 76,000 Miles
I have only had it a month and I am experiencing problems such as
a couple weeks ago I went to start my car in the morning and it would not start so I got a jump and it started after a couple mins. I can drive all day and turn it off and start it back up fine with no problem. Well recently I went and got the battery and alternator checked out and they both checked out fine. I was asked if I left anything on and I did not. And I have been told maybe electrical problem. Well yesterday I went to start my car and it did the same thing. Now I have a speed charger and I hook negative and positive to battery terminals to charge it and when I do my battery voltage reads around 12.1 or 13.1 but the percentage of my battery was around 45% so I charged it up to 100% but would not start. (it wants to turn over and sounds like low battery. All lights come on in car when attempting to start and it makes a dinging sound.) So I put it back on the charger after I charged it to 100% and it said around 75% it lost charge that fast?? So I once again charged it to 100% and it started right up the second time. I drove it around without shutting it off then finally got home after 15mins of driving and turned car off, and started it back up no problem. About 4 hours later I went out and started it and had no problem. I am stumped I cleaned my battery terminals and they had hardly no corrosion. I looked around for any frayed wires and did not see any also followed to started and did not find anything. Anyone have any ideas? I am not to familiar with cars I know a little but I have no clue when it comes to this. I have been told possible bad spot in starter, bad ground, bad wires somewhere also been told electrical. Now I have been told could be bad battery even though it check out ok. (I took it to auto-zone twice and they did the computer check.)
Asked Nov 29, 2013

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