Generally when this need arises for me 12vdc to 6vdc, I use a regulator, usually series 78XX or some simular family. Using the regulator semiconductors a heat sink is needed. However regulation can be variable from between/or lower than 12dc from source anywher from 3 to 12volts direct current. in general using one of these regulator chips 7volts direct current can be precisly regulated to the current specific load/capacity @ 6volts, so the regulated range can be between 7 and 12 volts, thats quite a range... Simularly a 24volt dc input can be regulated anywhere from 24volts tom 7volts(thats an even better range). So, the regulated output can renain mono-stable thruoght the performance range of the amp-hour capacity of the AH load of the battery, throught the discharge range[7 volts]. Anyone care to speculate on the minumuim state of charge(for the batt bank) when the regulator circuit exhausts it head room? Id say off hand you could utilize the batt state of charge down to 33 and 1/3rd from a full charge. If that not maximum potential, I dont know what is. So basically yes, voltage regulator chips regulate voltage precisely using PWM, without voltage drop, within a given current rating...
JW