I only used 1 pak for the entire pactice and racing all i did was repeak after every race and then i would discharge at nite then a new full charge in the morning i was using a heating pad to get the temp up my chage rate was ten amps...I ran 13.5 and 10.5 ten runs on one pak and it kept getting better and the pak was two months old...take that sub c lol ...Later Drew