On my 18MZ I have it set up to display the motor pack voltage. So a quick glance let's me know what the voltage is. I also have an alarm set to warn me of low voltage (under load). Pretty handy feature. One quick way to avoid the low pack situation is to simply check the pack before take off. I use one of the testers Hyperions sells (and everyone else copied). Just one more way to cross check.

http://www.rclipos.com/HP-EOSSENTRY.htm