qazokm
Posts: 2
Joined: Thu Sep 12, 2019 6:08 pm

Proyect: Autonomous robot with a rechargeable batteries

Thu Sep 12, 2019 6:13 pm

Hi!

I'm looking at the different ways to power the RPI Zero W (with some extras like a picam and some sensors) and a pair of dc motors of the n20 type of 6V and 200rpm.

Ideally, what I am looking for would be to be able to design a board with a 3.7V LiPo battery that can be charged while it is being used and provides the necessary current for the motors and the RPi Zero W.
I had thought of a charging system based on the TP4056 (or a better version since this is only 1A) and two step-up, one for the RPi and one for the engines.

I have few resources so before ordering the material (and the time it takes to arrive) I want to make sure as much as possible of the components, since I would try to design the board in Eagle.

This solution seems complicated and I also consider the option of using 18650 cells already connected in series to obtain 7.4V and use a step-down (LM2596 or similar) or just one cell and reuse the step-up.

All this is that it can bring complications such as over-current motors that I would try to solve with limiters.

That is, it would need two voltage outputs, one of 5V and another of 6V.

I can't find any scheme or way to do it where at least it is proven that this is correct, since at least I will need a maximum of about 2A at the exit, probably less (1.5A).

Hi, I'm looking at the different ways to power the RPI Zero W (with some extras like a picam and some sensors) and a pair of dc motors of the n20 type of 6V and 200rpm.

Ideally, what I am looking for would be to be able to design a board with a 3.7V LiPo battery that can be charged while it is being used and provides the necessary current for the motors and the RPi Zero W.
I had thought of a charging system based on the TP4056 (or a better version since this is only 1A) and two step-up, one for the RPi and one for the engines.

I have few resources so before ordering the material (and the time it takes to arrive) I want to make sure as much as possible of the components, since I would try to design the board in Eagle.

This solution seems complicated and I also consider the option of using 18650 cells already connected in series to obtain 7.4V and use a step-down (LM2596 or similar) or just one cell and reuse the step-up.

All this is that it can bring complications such as over-current motors that I would try to solve with limiters.

That is, it would need two voltage outputs, one of 5V and another of 6V.

I can't find any scheme or way to do it where at least it is proven that this is correct, since at least I will need a maximum of about 2A at the exit, probably less (1.5A).

Greetings, excuse my English and thank you very much., excuse my English and thank you very much.

blimpyway
Posts: 169
Joined: Mon Mar 19, 2018 1:18 pm

Re: Proyect: Autonomous robot with a rechargeable batteries

Sat Sep 14, 2019 7:29 pm

You can find power packs with usb in (for charging) and out (for PI & motors). The motors you mentioned work fine between 3 and 6V,
At 4.5-5V you will just get lower top speed. 150rpm instead of 200. Motor drivers might lose another 1V drop.. It depends on the type of driver.

For 7.4V you can go the RC-way, buy a RC charger and batteries, leave motors powered at batterie\s 6-8V and use a buck converter to feed 5V (300-400mA max) to the PI

You have to monitor battery voltage and power everything off somehow, to avoid battery damage from overdischarge.

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mikronauts
Posts: 2724
Joined: Sat Jan 05, 2013 7:28 pm
Contact: Website

Re: Proyect: Autonomous robot with a rechargeable batteries

Sat Sep 14, 2019 10:33 pm

You really should use independent batteries for the Pi and the motors.
Brownouts often corrupt the sd cards.
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

amcdonley
Posts: 181
Joined: Mon Jan 26, 2015 5:56 pm
Location: Florida, USA

Re: Proyect: Autonomous robot with a rechargeable batteries

Mon Sep 16, 2019 4:12 pm

Designing for running while charging can be a challenge.

For reference: https://alanmcdonley.wixsite.com/curiou ... -Challenge

qazokm
Posts: 2
Joined: Thu Sep 12, 2019 6:08 pm

Re: Proyect: Autonomous robot with a rechargeable batteries

Sat Sep 28, 2019 6:26 pm

The first of all, thank you for yours answers!

I try to connect the TP4056 module + MT3608 + RPi Zero W in the first time, but, in spite of RPi consume only 0,6A max in the boot, this enter in boot loop. TP4056 be supposed to that supply until 1A maximum. This boot loop does not occure with Power Supply + MT3608 (to discard this module).

What do you think may be happening?

Thank you again!

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