The voltage tests are fine, but for a more complete picture you would need to load test it and see what it holds. You need a tester for that.

At six years, it has provided you the service it was designed for. You may get a year or so more out of it, but at this point it comes down to deciding the value of xx more months, vs the inconvenience of it failing when you least expect it. If you carry jumper cables, and can always get a jump when it goes, and you are the only driver, it may make sense to run it out. On the other hand, if another family member may be driving it, or you depend on the vehicle and don't want to take a chance of getting stranded, it is usually good policy to replace it proactively around this age. I would.

Don't rely on the indicator eye in the battery, it means very little.

And idling it for 24 hours to recharge the battery isn't good for the vehicle at all.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue