External Power Supply

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External Power Supply

daemon13
Hi all,
I am working with firefly and want to use an external (ground) psu instead of the battery in order to power the autopilot, motors and the mastermind. Unfortunately I didn't find any info about the electrical characteristics(DC voltage-max current) that the psu must fulfill. Any advise is wellcome !!
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Re: External Power Supply

DavidJensen
I have an Asctec Pelican, which uses 3s 11.1V LiPo batteries. If you use the same batteries (I don't know what the Hummingbird uses), then this should work for you.

A fully charged battery is about 12.5V, and fully discharged is somewhere about 10.5V. I used a 12V power supply that I found on Amazon, very similar to this:

http://www.amazon.com/100-240V-Switching-Adapter-BMOUO-Flexible/dp/B00SWTC540/

What you need to keep in mind is that this power supply will only output 6 Amps of current. Your LiPo batteries can output much much more current (about 150 Amps, I believe), which is useful for flying.

DO NOT FLY WITH A WALL SUPPLY LIKE THIS ONE.

You can get a better supply that has a higher current output, but it will cost you more. I've turned on my motors while on the power supply, but I did not give them any thrust commands. Current requirements of the aircraft depend entirely on what you're doing with it. Sitting on the ground is low, hovering is high, ascending is very high.

You might notice that the power supply I linked has a little barrel connector, which won't connect to your batteries. Our Asctec batteries have this connector, called a "Multiplex Connector". You can buy them online.

http://www.flying-dog.co.uk/shop/images/connectors/MPX_6pin_connector.jpg

You need to just cut off the barrel connector and solder on the multiplex connector, and you're good to go. Make sure to check your voltage and make sure you connected everything properly before connecting it to your aircraft.
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Re: External Power Supply

daemon13
Thanks for your reply !
Basically, I want to fly it using external power supply, not only power the mastermind! So, I will need an external power supply able to provide sufficient current to the motors. The problem is that there is no info on the asctec wiki about "energy consumption", while flying.

edit: Firefly works with  3s 11.1V Lipo batteries as well!
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Re: External Power Supply

DavidJensen
I remember hearing from someone who used the pelican (modified) that it consumed approximately 450 W of power on average. Given a 12V input, 450 W would be 37.5 Amps continuous current.

Some quick calculations based on my experience...

Let's say you get 10 minutes of flight time with a 6000 mAh battery:

6Ah * (1/0.1666 hours) = 36 Amps of consumption

This would be an average, so you need to account for peak current consumption, which would occur when you apply a maximum thrust command. I don't have the experience to let you know what that is, but I would guess somewhere on the order of 70-80 Amps (remember, that battery can output about 150 Amps). If you reach the maximum current of your supply, I don't think it would damage the aircraft, but you would lose maneuverability (maybe you would be limited to 80% of maximum thrust, for example). If you have a high quality power supply, you shouldn't need to worry about damaging it.

I would highly recommend doing more research before committing to a power supply, but hopefully you find this helpful to give you a general idea of what you're looking at.

Also, keep in mind that tethering your aircraft with a power supply cable will probably affect flight performance.
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Re: External Power Supply

Adrián
We have the Graupner ultra duo plus 60 battery charger and an Asctec Pelican.
The output 3 of the charger provides 12V and 5A, can we use it with a cable adapter to MPX to power the Pelican?
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Re: External Power Supply

Adrián
I tried it and it worked. :)