Hi all,

I own a cessna T-206. I currently use LiPo batteries of type: 1300 mAh / 3S.

If I use bigger batteries, e.g. a LiPo 4S battery, what else equipment do I need to change on my plane? e.g. ESC?!

Thank you,
John

First of all, you must be sure the ESC will handle this higher voltage. Second, a larger battery means heavier flight loads. You could run into a situation that the plane is to heavy to fly or you consume more power based on the heavier weight.

How can I be sure about the ESC? Is there a method for calculating what ESC you need?

Thanks!

The esc should say what voltage it operates at. Make sure it matches what your setup is designed for. I am not sure about this, but a point to check before you do any modifications. A typical spec writeup for ESC's is shown in the below link from Tower Hobbies in the US. It shows the battery range that will work with this particluar ESC. Make sure the one you decide on will give you similar performance (multiple battery, current rating, and so on).

http://www3.towerhobbies.com/cgi-bin...&I=LXKSY6&P=ML

Thanks, that's all I needed to know

FWIW a larger Mah battery = more capacity = longer flight times. There comes a point where the weight negates the gains.

ok cool! I'll do some testing with 4S batteries

If your just looking for additional flight duration like the thread title says, don't increase the voltage. Use a 3s battery larger than 1300mAh, such as a 3s 1500mAh or a 3s 1800mAh lipo. Heck even a 2100mAh 3s lipo if your plane can handle the extra weight.

Yup as dFalcon says.

It can be quite surprising as to how much additional capacity you can add to a plane w/o greatly increasing wing loading to the point that it is problematic.

A 2100/2200 3S lipo will not noticably affect your plane's performance vis-a-vis landings, etc. but it will do several things for you...

- Flight times will be greatly extended.
- Voltage levels will remain higher throughout the flight, you plane will seem to develop and sustain more power
- There will be less wear and tear on the battery, so the new battery will last longer.

So go for it.

Unless you KNOW that your ESC can tolerate the higher voltage, AND that it's BEC at the higher voltage can sustain the same number of servos it does now, don't do it... DO NOT increase the voltage!

Most ESC's DROP the number of servos they can handle as the voltage goes UP.

It sounds counter-intuitive, but that is indeed the case... higher voltage = fewer servos.

Yes, you are headed in the wrong direction to increase flight time.
3s and 4s of equal capacity ie... 1300mah the 4s will not have a longer flight time in fact with higher voltage of the 4s pack (if you don't burn anything out) the battery may give less flight time.
To increase flight time you need a higher capacity battery (mah rating) not more cell 3s to 4s which only increases voltage not capacity.
Try a 2100mah 3s

Hi. I don't want to start another thread. I ordered a hydrofoam plane/boat/hover craft type deal. 12-15 ozs. I've been looking over everything, but it is fairly overwhelming.

Specifications:

L 23.6" x W 17.7"
Weight: 10.6-12.3oz
Recommendations:

Li-Poly Battery: 11.1V 2000mAH
RRP: 1000rpm
Charge Time: 1 Hour
Suitable Propeller: 10 x 6 inches
Radio Required: 4-Channel, 3 Servos

Can someone suggest some brushless /esc/receiver/lipo setups? Thanks!

This has everything you need.

And yes the battery is fine...

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRNF8&P=ML]Click me![/link]

Great, thanks! I've been looking at Raiden Tech stuff. Everything is very cheap . . . but mostly sold out.

Btw, most everyone focused on the ESC, but the motor also has to be able to handle the increased voltage from a 4s pack. If you run too much voltage through the motor, it will over heat. A lot of the small motors are not rated for 4s. I don't know what motor you have, but it's another thing to check.

Like the other guys said, you probably just want more capacity (mAh).

Correct about the motor. You probably will need to use a smaller diameter or lower pitch prop to keep from overloading the motor (and ESC) with the higher voltage.

This is another thing that is counter intuitive. The lower the voltage to the motor, the larger the prop can be without overloading the motor. This is due to the fact that the torque needed to turn a prop goes up with the square of the rpm.

OK, cool. I just want to extend flight duration, not increase thrust. 3S 2100 mAh sounds good if I can fit them in the plane's limited battery space...

Measure the battery space you have and find a battery that will fit it. Some planes come with the battery space for the size battery you have now and can't go bigger without makeing some cuts in something. Also, going 4S, on almost every ESC I have looked at, you need a seperate battery for the reveiver and servos, or an seprate BEC to run them. The built-in BEC is to limited to run no more then 3 cells. The battery sites will give you the dementions of the battery, so if you know the space size, you can pick your battery with that in mind. Just make sure your plane will still ballance with the new battery. If your space is big enough, you can move the battery back to reballance the plane, but if it is to small, you are going to be stuck with a smaller battery.
Ed

For what it's worth, the power an electic motor delivers to the prop goes up exponentially with increasing voltage. Going from 3 to 4 cells will just about double the motor's power, if it doesn't burn up first. The same prop that is a perfect match for the motor with 3 cells will grotesquely overload the same motor with 4 cells.

This is why a good amp meter/ watt meter, is a must have item for everybody who is seriously into electrics. Every time you try a different prop, gear ratio, or cell count, you need to check the amp draw at full throttle. The price of a amp meter is a bargain compared to fried ESCs and smoking motors.