What size battery does one need for to use with 4 servos,5 servos,7 servos. Is there some sort of printed info on this subject? Of a rule of thump to use?

I use 4.8 VDC 600 mAh Batterys in some of my planes.

I also use 4.8 VDC 1000 mAh Batterys in some..

You get a little longer flight time with the 1000.

I find that eather one works fine for our size planes..

Yea What Don Says!
Also when you go up in the servos or if it is digital or analog servos the amperage draw gets higher. Some people use a seperate regulator and power supply to the servos and reciever. Of corse the smaller battery supply will be at the reciever.
Hope this helps.

Thankyou Don K and ROV for your input,this gives me a better idea of what size battery to use. Thankyou.

Anytime! :thumbup:

There are many variables to servos vs batteries. For a standard plane, starting with a 4 channel then a 600-800 mah pack will be good. Whenever you add a servo I'd probably step up to next size bigger pack, ie, 4 servos, 600, 5 servos 800, 6 servos 1000 mah etc. It's always better to have extra power than not enough ;)

If you start using digital servos then you definately want to use a bigger pack as they can draw much higher amounts of power (especially for 3d type of flying).

Another good idea is that when you get an airplane 1.2 sized or larger install a 2nd switch and battery of the same size so that you have a redundant system (cheap $20 insurance for a plane worth probably $1000)

As far as types of batteries, I've used nicd, nihm, lipo and li ions. All of these work well just keep a good eye on them by checking them often if not every time you fly!!

A quick exp of batteries is:

Nicad, ni cad batteries, hold their charge similar to times of nihm batteries. Ni cads will gradually loose their power over flying time. Their graph would look somewhat like a light sloping hill. Nicads will also build a 'memory' over time, ie, if you only use about half the pack continuously and then recharge the pack will get to where that's all of the charge that it will want to take so it's good to cycle nicads periodically.

Nihm, nickel metal hydride, batteries last about the same amount of flying time as nicads but hold a more consistent charge. The graph on them would look more like a very slight hill with a minor cliff at the end. An advantage of nihms also is that they wont develope the memory that nicads can. I use a lot of nihm batteries

lipo, lithium polymer, we use a lot of these on the electric planes. They are light with long lasting power output!!! You have to be careful with the lipo and li ion batteries. Charging them with a charger not made for them can cause them to blow up and catch fire!! Lipo batteries can be damaged more easily than the li ions and can catch fire much more easily (but don't be afraid to use them)!!!

Li ion, lithium ion, these are more common in the giant scale planes. They are light, hold a big charge and are pretty safe.