I have been flying RC planes and 'driving' RC cars for a long time.

Why do RC planes use 4.8V (4 cells) and cars use 6.0V (5 cells).

I have used 6 volt 5 cell batteries in most of my 1/4 scale and up planes, because I have High tourque servo's in them.
NEDYOB

We have been using 6V in planes for several years now. I too use it for scale and large aircraft where more power and/or speed is needed. On smaller planes, weight is a bigger issue than more volts. Remember, aircraft have wing loading issues that cars don't.

I've been using 6V NiMH with 2.4GHz receiver and Digital servos for about a year. This setup has worked perfectly for me, however recently I've read some info about 6V being too much for the servos. Is there anything to worry about here? I notice that some Futaba servos do specify 4.6V only and Futaba seems to recommend NiCad over NiMH. I've been wondering if I should switch to NiCads and 4.6V Does anyone have some solid technical information on this subject?
Regards
JC

Some futaba servos recomend 4.8v 4cell packs, not all. This is because there are some servos that cant run 5cell packs because the voltage is too high. A freshly charged 5cell pack will be well over 6volts and some servos just dont work correcly over 6volts. even JR has some troble with this its not only futaba.

as far as the NIMH Vs NiCad...

Nicads wont be as much over their rated capacity unlike NIMH's a freshly cahrged Nicad might be a little above 6 volts, but the Nimh will be well above 6volts

Most Nicads have a higher discharge rate than NiMH's. If runing multiple high load servos some Nimh migh over load

I have cars that I use 4.8v packs and planes that I use 6v packs. It just depends on what I use the model for and what radio gear is fitted.

Cars run 6V as you want more torque and also speed,nothing beats using more volts to get that. Planes can live with 4.8V most of the times. But with today's demanding flying styles quite a few are turning to 6V for planes. I still run both 4.8 r 6 depending on what sort of plane.

ive been ussing 6 volt on my JR rxs for 3 years now without a problem. digitals and regular.

The servos that have a problem with 6v are generally special use servos like helicopter tail rotor servos that operate off a gyro at a very high frame rate.

Lots of flyers using 5 cells are also using a voltage regulator to keep the voltage from going above 6 volts and damaging servos or a receiver. I personally am using 2 cell 7.4v 1600mah lipos with a 6 volt regulator in my planes. Much lighter weight than Nicd or Nimh and I can fly all day.

I use a 6 volt 5 cell battery to fly my black horse chipmunk because im running 7 servoes

I have been using 4.8V but since switching to Spektrum I am on 6V now.

When the servos can't take 6V I use a 5 cell combined with a regulator. This way I'm sure my Rx & servos are getting a steady 5.2V.

This is the regulator (BEC) I use:
http://www3.towerhobbies.com/cgi-bin...&I=LXSWL3&P=ML

The 1st thing to do is check the battery voltage right after it's off the charger and see what the voltage is.
All you need to do is insert a voltage dropping diode in 1 line and it should drop appx 1 volt.
However if your just running a trainer with 4 servos and little load I would just stick with the 4.8 volts and go with a higher MaH battery.
Vegas/

Oh I forgot to say that the big problem is that you get no paper work with the RX and TX.
But mst solid state devices today will tolorate 15% of the rated operating voltages
On my older trainer I been running 12 @ 2 amps on the TX that takes a 9.6 volt battery and it's been more then a year now and no ptoblems.
My 2 meter ham radio HT takes a 9.6 volt battery but I still plug it in the cigarette lighter and it's running off 14.2 volts when driving
Just my 2 cents.
Ops Make that 1 cent
Gas here went down to $2.47
Vegas/

I use 4.8 volts on .90 and smaller planes, 6 volts on larger planes. Larger planes have larger control surfaces, and therefore are exposed to more force. 6 volts gives the servos more power to compensate.

It's the AMPS that give you the force you need
Just like the factory stock TX batteries come out with 9.6 volts at 700 mils.
Might be good for 4 flights.
A 9.6 rated at 1.8 or even a full 2.0 MaH will let you fly all day.
Amps is the power needed for that extra force.
Vegas/