Hi,
5 minutes should not have such an effect esp. onn a car theat is relatively new. I agree with you about dipped headlights - it would be good if it was made a stadard feature on all vehicles sold. i remember that Telecom Eireann made this adjustment to their fleet of vans and reduced accidents dramatically - it has a negligible impact on fuel consumption.
As previous poster said, check water level - it should not be too difficult to get distilled water. IFor the moment as the battery is weak, make sure allitems that draw on the battery (lights, fans) are turned off before trying to start her up!
Slán