More than likely you will be ok charging Friday night and flying on Sunday. How much charge you lose depends on a lot of things like the type of battery, the age of the battery, the condition of the battery, and a few others too. But you get the general idea. The best way to find out is to check it out yourself. Charge your batteries normally as you would on Friday night, then skip a day, and use an extended scale voltmeter to check the voltage of your batteries on the morning of the second day.

A great resource to learn just about everything there is to know about the batteries we use in this hobby can be found at [link=http://www.rcbatteryclinic.com]www.rcbatteryclinic.com[/link] . It's well worth the time spent to spend a couple of hours on his site reading up about batteries.

Hope this helps

Ken