Do digital servos cause a higher battery drain than regular servos and same question for high torque servos? If so what rx battery would be recommended for a plane using 6 high torque servos? Would a standard 600 mah battery be to small. This is regarding a GP RV-4.

Yes, digital servos and higher torque servo requier more juice. Digital high torques draw a lot of amps, high torque servos alone arn't to bad. My funtana x50 has hs 475 wich are kind of high torque servos. 4 of them burn anywhere from 150-200 mah a flight. My stinger .50 heli has high torque digitals and i burn up 600 mah a flight.

Batteries aren't very expensive. Get a 5 cell Nimh with about 1500 mah. You won't be able to charge with the wall wart charger that came with your radio and will have to get something with a little more oomph, but just about everyone in this hobby has bought a more sophisticated charger. I like the Sirius products.

cambo is correct when he says that they require a higher capacity battery.
a standard 600 mah battery will power your servos but not for long. you see mah stands for mili amp hour so a 600 mah battery can produce 1 mah for 600 hrs or 600 mah for 1 hr.
some will say go to 6 volt battery. all that does is make your servos faster. to answer your question perhaps a 1200 or 1500 mah battery will do you. always check with an expanded scale volt meter, to check the true charge of your battery under load when in doubt

http://www.hangtimes.com get a decent capacity pack and invest in a good charger/cycler like the AccuCycle elite or something similar, its cheaper than replacing a model because a pack failed you at an opportune time.

There have been two magazine articles in the last year or so that compared the battery drain of digitals and analog servos.

Both magazines came to the same conclusion. The two drain about the same depending on how you fly. And whether or not you've rigged your servos right. One of them suggested the differences they found wouldn't amount to the difference in capacity of one flight.

Remember that moving from a 4.8 volt to 6 volt pack will make your servos move quicker
and give them more torque. The downside is that because the torque and speed have increased
so does the current draw which is why it is reccomended to get a rather high capacity 6 volt
pack when changing from 4.8 volts.

This is the battery I use in my RV-4.(also available in 4.8v for $19.99)
http://www2.towerhobbies.com/cgi-bin...&I=LXNHS4&P=ML
So far I have never had a low battery at the field but 5 or 6 flights a day is about it for me.