Airsoft Outlet NW have some new electronics out that will let you know when your LiPo battery is running low:
Hey Arnie,
We’ve recently developed Lipo Alarms for 7.4v and 11.1v Lipo battery packs. These alarms notify the player when the charge on their Lipo battery is dangerously low and should be replaced. These simple chips are easy to install and do not take up much space; anyone who runs, or wants to run, a Lipo in their AEG should consider a Lipo Alarm to protect their investment.
7.4v alarm: (http://www.airsoftoutletnw.com/index.php/7.4v-Lipo-Alarm-Board-Li-po-Battery-Protector.html)
11.1v alarm: (http://www.airsoftoutletnw.com/index.php/Airsoft-Batteries-BB-s-Gas-Chargers/Airsoft-Batteries/Lipo/11.1v-Lipo-Alarm-Board-Li-po-Battery-Protector.html)article on their functionality: (http://airsoftoutletnw.typepad.com/blog/2010/11/airsoft-lipo-protection.html)
Thanks again, Ben (Airsoft Outlet NW)