Want to double check my figures... Power requirements for QuadRotor kit...

Hi,

I am building a quadrotor from the full kit provided by store.DIYDrones.com.

The power distribution board refers to a 5V out.  Giving me the idea this thing runs on 5 volts...

 

when I first asked the sales team what batteries to buy, they sent me to some 3 cell 11.1V turnigy nanotech 2200mAh 45-60C discharge batteries.

 

I was surprised the kit doesn't seem to come with any kind of voltage regulator to bring 11.1 volts down to 5volts.  Would this imply that the kit (motors, APM 2.5, etc.) are tolerant of a 11.1 volt supply?

 

OR, am I missing something like a voltage regulator, or possibly have purchased the wrong batteries?

 

Thanks for your help!

 

Matt Christenson

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Escs have a battery elimination circuit or BEC. This will supply a standard 5v to APM.
Jason

You really need to read the directions. The APM get's 5 volts from the ESC (Electronic Speed Control) for the motors that inlcudes a BEC( Battery Eliminator Circuit, AKA voltage regulator) to supply the APM with 5 Volts regulated from the battery.

http://code.google.com/p/arducopter/wiki/APM2board

It's also possible to power APM 2 from two separate sources, one powering the RC system on the input side, and the other powering the output side (servos or ESCs). This is determined by a jumper on the JP1 pins (see below). If the jumper is on, which is the factory default, the board is powered from the Output rail. If the jumper is off, the board is powered from the Input rail, but the Output rail will need its own power source. This configuration is used if you want to have two seperate power sources in your aircraft, one powering the servos and the other powering the electronics. 

The APM2 is designed to properly operate from a clean, well filtered power source. Be aware that the voltage specifications are different depending on which connectors are used. The reason for this is there is a schottky diode (diode D1) that prevents the USB port, when connected, from sending power to the APM2's PWM Output connector and damaging something. Consequently, when the USB is not powered and power is connected via the PWM Output connecter there is small voltage drop across this diode in normal operation and a higher input voltage is required to compensate. Therefore, power requirements are as follows: 5.0VDC +/- 0.5V supplied into the PWM input connector, jumper JP-1 removed.  5.37VDC +/- 0.5v supplied into the PWM output connector, jumper JP-1 in place

Warning: Do not exceed 6.0V DC of power supply input voltage or you will damage your board.

In some cases it may be a good idea to set the input voltage slightly above the median (but below the maximum) to account for possible voltage drops during momentary high current events.

The APM2 by itself draws relatively little current (200ma range) and a power source capable of providing 300 - 500ma will provide plenty of margin. However, if servos or other power consuming devices are being driven by the same power source you must consider the power  requirements for those devices as well and provide plenty of margin to prevent disastrous "brown-outs". For instance, a single digital servo can easily draw 1-5 amps depending on it's size and performance. (Note: ESCs do not consume power from the APM) If you experience spurious resets or other odd behavior it is most likely due to noisy or insufficient power to the APM. As with all logic boards, electrical noise from the motors, servos, or other high current devices  on the power source can cause unpredictable behavior. It is recommend that a power filter such as this or this be used in such conditions.

Also, let me add I'm concerned you need to do lot of reading before you plug anything in. It's an assumption on my part but since you asked the questions, I am doubting your experience with radio controls, ESCs, and brushless motors. If you haven't used those basic RC components before and do not have significant experience, you are going to have some problems with the directions since they assume you already know the basics. You might be well served to hook up with someone local that does play with RC and has the brushless motor thing down. That's not to say you cannot build or fly, just you seem to be at risk unless you follow the directions step by step from the link and if you don't understand, ask before you power anything up. I'm glad you asked the question and we are more than happy to help out, just keep asking questions.

And sorry to put this guy back out there but hard lesson learned http://diydrones.com/forum/topics/rookie-mistake-in-powering-up-my-...

Hopefully his expensive mistake prevents someone else from doing the same. Again, sorry for his loss.

You were right that the electronics run on 5V, and you do need some form of regulated power supply.

The simplest method is to use one of the built in BEC's in the ESC's, but I personally don't like this and install a separate BEC connected to the main battery rail of the PDB.

The PDB's are setup to take the 5V from the ESC's BEC, if you look closely at the wiring diagrams in the Wiki.

Thank you to everyone for the help.  While I'm still waiting for the arms of my quad to get it functional, we soldered up most of the parts today and after a lot of research connected one motor directly to the RC module and got it to spin from the throttle input - so we know that parts working!  Can't wait until two weeks from today, when we finish assembling the unit.

 

Matt Christenson

Mike, can you link me to the BEC that you use as the separate power source?

I use mainly Hyperion gear as it is the best and most consistent quality I have found.

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