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Maritime-Robotics-Student-Society / sailing-robot

Southampton sailing robot
http://www.sotonsailrobot.org
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1 battery to power the entire boat #263

Open CamilV opened 6 years ago

CamilV commented 6 years ago

Currently, the Pi is powered with a USB Powerbank and the servos are powered from 4 AA batteries. I'm thinking, powering the whole boat from a single 2S LiPo or something close to that, might be possible and it would facilitate test preparation and simplify the wiring

ReFil commented 6 years ago

Yes this would be trivial to manage with a high current BEC, although I'd suggest using a 4s 1300 or something along those lines

CamilV commented 6 years ago

Why would you recommend a 4S? The Pi requires a power supply of 5V and the servos work well with voltage levels as low as 4.5V. My idea was to step down the voltage with a buck converter to power the Pi, ensuring a constant 5V supply and have another buck converter to power the servos. The maximum current we saw being drawn by the servos was about 800mA, which would result in almost no voltage drop across the battery.

ReFil commented 6 years ago

If something goes wrong and you need to keep power up you have more margin to discharge a 4s below its rated voltage maintaining 5v for the supply. A 2s would work, but for stuff I do, I always have a nice big margin. also if you use an 18650 pack for better energy density you'd need at least a 3s as 18650 cut off voltage is around 2.5v per cell depending on the cells you choose

On Sat, Oct 20, 2018 at 12:05 PM CamilV notifications@github.com wrote:

Why would you recommend a 4S? The Pi requires a power supply of 5V and the servos work well with voltage levels as low as 4.5V. My idea was to step down the voltage with a buck converter to power the Pi, ensuring a constant 5V supply and have another buck converter to power the servos. The maximum current we saw being drawn by the servos was about 800mA, which would result in almost no voltage drop across the battery.

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