4.8 Volt or 6 Volt?
Here is an email that answers most peoples questions who are considering a 5 cell pack:
Q: "Dave, one last question, then I will be sending you an order to upgrade my
batteries. What is the difference between 4.8 and 6 volt receiver batteries besides weight?"
A: A 6 volt pack allows some additional safety as one cell can short and you still have enough voltage to keep flying. That is not to say that any type of cell failure is covered if you use 6 volts. A cell can always open up and not amount of voltage is going to help you then. The extra voltage will give your servos more speed and more torque. The increased speed will give your airplane a feeling of crisper roll damping. Flying time will be slightly reduced with a 6V pack over the exact same capacity 4.8V pack. This is a minor reduction and should not enter into any typical battery choice decision.
Q: "My Futaba manual says that the receiver will use both voltages."
A: Yes, as it is made to accept 4 Alkalines which is 6 volts.
Q: "What, if any, performance increase will the 6 volt battery give? What specifically will increase (better reception (whatever that means)? Less interference? Faster servo travel velocity?, etc.?). Thanks, David H."
A: More torque. and more holding power. Torque will typically increases more than 25% and of course, faster rotation speeds. The speed back to center is the part you might see the most in your flying. I have heard it argued (by those who are more knowledgeable than I) that many receivers have more range and are slightly narrower band with more voltage.
You will occasionally have a jittery servos when you first turn on a freshly charged 6V pack. This usually goes away in just a few seconds. The peak voltage of a fully charged 6V pack is well over 7 volts. But, it settles down quickly.
For most of my smaller and normal sized ships, I am chasing weight savings and use 4.8V. I do use 6V on a combat model and would use it on any large model (or twin packs/twin switch harness setup) as I like redundancy in ships that are more important to me. There are many different views on this subject and you will probably get 5 different ones if you as 5 different people.
About 90% of all packs in use are 4.8V. 4.8V is fine. If you are searching for extra torque, more speed or need some redundancy, 6V is a good choice.