quyetflyer

Hey guys....question for ya....i have a threedee. It runs a speed 400 with a 3:1 gearbox,10X7 prop,10cell 600mah nicad. The motor is the 6V version. I also have a speed 400 7.2V version. What would happen if i used the 7.2v motor?..i dont understand the difference...thanks!-jordan

SignalMan

Hi Jordan;

I'm fairly certain your nickel-cadmium (nicad) battery is
rated 1.2 volts per cell.
This number multiplied by 10 cells is 12 volts.
Because the one motor is rated at 6 volts, this means the
battery cells are connected in series-parallel to provide the
proper 6 volts required by the motor.

If you use the 7.2 volt motor with the same battery,
your speed will be lower and the motor won't be operating
at its full designed power.

The advantage the 7.2 volt motor has is lower current draw
for the speed and output power when operated at 7.2 volts.

So, by all means use the 7.2 volt motor if you can also
use a 12 cell battery in place of the 10 cell unit.
It's perhaps is a catch 22 at some point though, because
obviously you gain more cell weight by increasing to
7.2 volts.

I hope this is somewhat helpful.

John

quyetflyer

Thanks jon...thats exactly the info i needed....i hooked up the 7.2 volt and Yep, less rpm...ill stick with the 6v and keep my airspeed up!...thanks again

Matt Kirsch

My Feedback: (21)

More specifically, the "V" rating on Graupner Speed-series motors is a vague way of describing how the motor is wound. That is, the number of turns of wire wrapped on each arm of the armature.

With the Graupner motors, it's a relative rating. A 6V Speed 400 is "hotter" than a 7.2V Speed 400, because it has fewer turns of wire.

The less wire, the less resistance.
The less resistance, the more current will flow.
The more current that flows, the stronger the magnetic fields.
The stronger the magnetic fields, the harder they pull toward each other.
The harder the magnets pull toward each other, the faster the motor turns on a given voltage.