At the field, my instructor checks the receiver batteries about every 2-3 flights, only takes a second if you leave your wire hang out the right side of the fuse or if you have a charger jack installed with your switch and the voltmeters that pull a load are only about $10 at TH. If the receiver battery gets under 5v he will use a field quick charger to bring them back up but only 1 time. After that the night is done and it's back to the radio charger for the slow charge. As a side note (don't ask how I found out) my batteries were fully charged when I left for work yesterday. When I started flying I was only reading 5.1v.....I was told not to leave them in a hot car all day as the heat will pull the charge down (learned something new!). Two short flights and a quick charge and I was good to go for the rest of the night.