you have to drive considerably at higher rpm for the battery to recharge. 5mile trip is hardly enough to charge the battery... in fact, it will drain it.
i put my dd on a battery manager every weekend as my commute is only 11-12 miles one way. it's not enough to have a healthy charge. i will add im on a 8yr old original battery and started up fine in -2F weather.
i do add distilled water from time to time (once every 3yrs) when the cells show a dip in level.