Robot Power Suggestion

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Hal3Roseman
 
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Robot Power Suggestion

Post by Hal3Roseman »

Hello All and Thanks In Advance!

I am building a small rover robot for my home and I am looking for a way to power it.
I am having trouble sorting through all of the possibilities offered by Adafruit.
My need is as follows:
- Two power feeds: 1) Raspberry Pi; 2) motors
- Rechargeable Power
- Circuit that can be recharging the batteries while still powering the robot
- Nice to have: a way to recharge the batteries by having the robot dock itself to a charger.

Thanks! I look forward to your guidance.

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Franklin97355
 
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Re: Robot Power Suggestion

Post by Franklin97355 »

Define "small". How much does it weigh and what terrain does it travel? Can you use a RC car?

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adafruit_support_bill
 
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Re: Robot Power Suggestion

Post by adafruit_support_bill »

Motors are going to be your primary load. So you should choose a battery pack voltage based on the motors you will be using. You can derive power for the Pi from that using a buck converter. That is much more efficient than trying to boost voltage to run motors.

Pack capacity will again depend on the needs of your motors - as well as the expected run-time between charges.

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Hal3Roseman
 
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Re: Robot Power Suggestion

Post by Hal3Roseman »

It's a small rover - 2 wheels/motors -

Motor Specifications Suggested Voltage: 4.5VDC No Load Speed: 140RPM No Load Current: 190mA Max. Load Current: 250mA Torque: 800 gf-cm
IMG_2544.jpg
IMG_2544.jpg (682.15 KiB) Viewed 69 times

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adafruit_support_bill
 
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Re: Robot Power Suggestion

Post by adafruit_support_bill »

Brushed DC motor voltage specs are typically pretty loose, so these will probably run reasonably well on anything from 3v-6v. Since your Pi will need 5v, I'd probably go with a 6v NiMH pack.

You can use a buck converter to derive the 5v for the Pi. Check the Raspberry Pi site for the current requirements for the model you will be using.
https://www.adafruit.com/?q=buck+conver ... =BestMatch

You could use a buck converter for the motors too. But that is not really necessary. Assuming that the motor drivers on your rover have PWM control, I'd just limit the throttle in your code so that the average duty cycle does not exceed 75% for extended periods.

Battery specialist sites or RC hobby shops are the best source for NiMH packs & chargers.

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