After going for a 30 min highway drive in the X5 around 2pm yesterday I brought it back and trickle charged it at 2amps till about 7pm. Then it sat in my heated garage (+5 Celsius) till 10am Sunday...I just checked the battery voltage and before starting was 12.1volts and then with engine running at idle it was about 14-15volts, ran it 2 minutes while testing, then shut it off the voltage was 12.02.