I am building/designing a quad-copter and will need to power 4 servos, 4 brushless motors, nrf210.... reciver/transmitter, an accelerator, and a gyroscope. I have a battery in mind but I'm not certain this will be able to power all of the components as well as the core micro controller. Any ideas on what power supply to use?
The brushless motors and ESC's that drive them typically have a limited range of voltage over which they are designed to work. This is generally expressed as how many 3.7V LiPo cells you would put in series: 1S=3.7V, 2S=7.4V, 3S=11.1V...
If you have chosen the motors and drivers, pick a battery that fits within their operating range.
For 5V devices like servos, radios, and Arduinos you use a Battery Eliminator Circuit (BEC) which will regulate the battery voltage down to 5V. Unless you have "OPTO" ESC's you will find that your ESC's all have BEC's and will feed 5V on the red wire to whatever they are connected to.
While choosing a battery you first need to calculate the peak current draw of your whole system then check the voltage that your devices can handle if this is fine too you need to look at the space your battery will consume like you said you want to build a quadrocopter which means your system should be light weight and after that you need to know that multiple cell batteries need a balance charger to charge properly
P.S you will also need to use an appropriate protection circuit.
I foresee a puffy battery pack in your future. Or melted wires.
That battery is not intended to be a flight battery. It is a transmitter battery, intended to power a transmitter with very little current demands compared to powerful motor like you specify.
If you pull more current from a pack that it can safely deliver, it gets puffy and has a reduced capacity from that point on.
You want a battery that is designed to be a flight battery. You have 4 big motors that will probably be turning big props. You need to find out how much current, like @NewStudent said.
The motor specs say 20-48A for efficient flight. 80A max. Times 4, that is a lot of power.
You will need larger packs that that one. Likely multiple packs configured in parallel to be able to handle a large current demand like what you are planning.
Here is a 3000mAh pack that can safely provide 40C
You likely need multiples in parallel.
This is a cheap charger that can plug in to the wall and charge one battery at a time. Likely will take more than an hour to charge each battery.
There are more expensive chargers that can charge faster, and multiple batteries at once. Most of them do not plug into the wall. The require a 12V power supply.
This is a voltage regulator that can turn the 11.1V pack power to the 5 or 6V that your servos require.
https://hobbyking.com/en_us
/turnigy-5a-8-26v-sbec-for-lipo.html
Great, thanks for all the information. Since the props will be turned by brush-less motors how can I regulate the power (to regulate the spin speed aka flight control)?
Note: I'm having trouble with the calculations needed to find the proper current I need to power everything, but i'll be consulting with my physics teacher tomorrow morning. By the looks of things i'll need around 450A (over-estimation) to power every component. Aside from the needed power I'm unsure on where to begin with using the ESCs and how to hook them up properly. (I'll be researching this.)
You use an Electronic Speed Control (ESC) for each BLDC motor. An ESC is controlled just like a servo. Motor.writeMicroseconds(1000) turns the motor off. Motor.writeMicroseconds(2000) turns the motor up full. Values between 1000 and 2000 control the power.
Note: the motor you listed is NOT designed for a quadcopter. It is designed for a helicopter. You should probably find a commercial quadcopter that matches your desired size and pick your motors, ESCs, propellers, and battery to match that design.
Here is a speed control that can turn those motors.
https:
//hobbyking.com/en_us/turnigy-plush-100a-w-ubec-speed-controller.html
At $50 each, you are in for $200 for a set of four.
Immortal_Conqueror:
Great, thanks for all the information. Since the props will be turned by brush-less motors how can I regulate the power (to regulate the spin speed aka flight control)?
You talk to the ESC the same way that you talk to a servo.
Create a servo object for each ESC.
Write a starting position for the servo and attach it.
There is likely an arming sequence - something like
- write zero to the servo
- wait 3 seconds
- write full throttle to the servo
- wait 3 seconds (and the motor will likely beep)
- write zero to the servo
After this any writes to the servo will start or stop the motor. With a prop attached, this can surprise you so make sure your initial tests are with the motor FIRMLY attached to something immovable. NOT someone holding the motor or the airframe.
Note: I'm having trouble with the calculations needed to find the proper current I need to power everything, but i'll be consulting with my physics teacher tomorrow morning.
I bet you do not have all the information you need to determine this.
Maybe not all the equipment.
Do you know what props you will be using? (remember to get CW and CCW pairs) (and get spares. Several sets)
Do you have a Watt meter? https://hobbyking.com/en_us/turnigy-180a-watt-meter-and-power-analyzer.html
I would start with a guess of what you think the airframe AUW will be (All Up Weight)
divide by 4. to get the thrust a single motor will need to provide.
Make a test rig with a fish scale or some way to measure thrust of a single motor.
Put the watt meter between the battery and ESC, where it can be read without danger from the spinning prop.
Run up the throttle and measure the thrust, noting the critical numbers on the Watt meter, specifically the amps.
Make several readings under and over the target thrust, so you know what the thrust to amps curve looks like.
Now, as you move forward with your project, any changes to the AUW can be plotted on your curve to get the new total current draw.
I have to ask this question. Why this motor? Is it a solution to your calculations on how much power you need?
I ask because if the motor was picked because it is what you found, or it is cheap, you might be going about this the wrong way.
It is MUCH easier to go with equipment that has been shown to work. There are a LOT of guys on the quad forums who have already created quads with known components.
A certain capacity battery gives a certain flight time carrying the quad and a camera of a certain weight and battery of a certain weight.
Starting with those equipment sets means that you will be in a known usable collection of equipment.
Hence my question, why those motors.
Oh, another variable that using known equipment will resolve - motor kv. Heli motors are geared, so are probably going to be a higher kv. Quad motors are direct drive so will be a lower kv. Which are you going to buy? How do you know? (hint, this is why I think it would be a good idea to look into known good sets of equipment used by the quad guys)
I chose that motor because I had presumed the high rpm and high power would enable me to more or less ignore any weight constraints. But looking more into it I see where you're coming from. I have a Watt meter, but not the proper knowledge on the electrical physics for the quad-copter.
The props I'm looking at are pretty large, not sure if they're too big.
I have a few motors in mind but am unsure which would be best for the somewhat high-weight i'll be working with.
Motors 1-3 have been used by quad-copter creators before, but they seem to be for the smaller quad-copters.
Motors 4 & 5 are sold as helicopter motors, but they look like they'd be perfect for a high weight quad-copter.
If you spin a propeller very fast you have to use a small diameter propeller to keep the tip speed below the speed of sound. Take the battery voltage (2S=2*3.7V=7.4V) and multiply by the speed rating (3800 kv) and then by 1000 to get RPM ("kv" is thousands of RPM per volt). You can calculate the tip speed as RPM * Pi * diameter to get distance per minute. If that exceeds the speed of sound you should pick smaller diameter propellers.
Details are essential if you want any real help.
If you give us numbers for the "somewhat high weight" you want to lift (total flying weight including the battery and any load) then we can help with the motors. But at the moment we know nothing useful except you want 4 of them.
And to choose a battery you also need to know how long you need to fly for (as a number of minutes). "Not very long" or "a reasonable time" won't do.
Steve
Weight List
-Servos 22g *4
-RF Trans./Rec. 25g *1
-Props 19g *4
-Accel/Gyro Chip 2.5g *1
-Microcontroller 37g *1
-Frame *1 450g
Total: 678.5g or .6785kg
-Batteries: Unknown Weight
-Motors: Unknown Weight
Goal Fly Time: 25min. - 60min.
I'm not sure how you're approaching this design but you need to have some idea of the size (the frame will weigh something) and what the total flying weight should be. If you can't make a reasonable estimate of those, perhaps based on a commercial quadcopter similar to the one you're trying to build, then you can't sensibly choose either motors or a battery.
Steve
Just put in the frame, I was in a rush yesterday, apologies m8.
12" propellers are mighty big. One reference recommends a max RPM of 105000/inches so 8750 RPM. With a 2S (7.4V) battery that would mean a 1182kv (max) motor. With a 3S (11.1V) battery it would be a 788kv (max) motor. That should help you narrow down the motor choices.
I'm gravitating toward a 11.1V battery, however for no particular reason. I've listed a series of motors that may be the best for the job but am still not sure.
Ongoing Dicussion on rcgroups.com
4 more motors have been listed on the rcgroup forum.
Immortal_Conqueror:
I'm gravitating toward a 11.1V battery, however for no particular reason. I've listed a series of motors that may be the best for the job but am still not sure.
The first motor (650kv) might possibly be suitable. They recommend prop sizes 144.7 or 154 but the higher pitch, smaller diameter propellers might work.
The second motor (610kv) actually lists your propeller size (12x6) as a recommended size. I WOULD GO WITH THIS ONE.
BOTH of those motors recommend a 4S battery (14.8V) so you will need to adjust your battery choice to match.
Alright. But i'm not certain of the flight time the motors will be able to provide with a moderate battery weight. I'd like to have an efficient weight to flight time ratio where I'm not buying tons of batteries for an inefficient motor (in relation to the carrying weight) to ensure a long flight time.
This article: http://www.flyingtech.co.uk/blog/efficiency-vs-performance-how-build-drone-long-flight-time purports to talk about efficiency and recommends higher voltage but when you use the motor specification table they provide (dys brand BE4215-21) to calculate grams of thrust per Watt the lowest voltage (3S) and smallest propeller (10x4.7) come out as the most efficient (7.7 grams per Watt). The same motor on a 6S battery gives 3.9, 2.7, and 2.6 grams per Watt for the three propeller sizes.
Even when you subtract the weight of the motor (83g) and ESC (39g) from the thrust the 3S voltage is STILL more efficient than the higher voltages. That means it is better to add more motors at 3S than to run the motors at higher voltage to get the most flight time per Watt-hour.
Maybe you should go to the dys website (http://www.dys.hk) and pour through their motor specifications to find the highest efficiency motor/propeller combination. That will give you an idea of what combination will give the longest flight for a given battery capacity.