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kit:mod_battery_power

This is an old revision of the document!


January 19, 2019 - This article is still being authored. This information is not yet ready to use!!!

Introduction

Converting a CrowBox to run from battery power is an easy thing to do and makes it possible to deploy a CrowBox in locations which do not have easy access to mains power.

CrowBox Power

Before we talk about the modifications required to run a CrowBox from battery power, we should briefly talk about the CrowBox's power consumption details.

  • The CrowBox runs on 5 volt DC power
  • An idle CrowBox consumes about 50 milliamperes of current
    • This power is consumed by the Arduino UNO
  • When the CrowBox's sliding lid is moving (opening or closing) the CrowBox consumes about 800 milliamperes of power
    • It is possible for the CrowBox servo motor to consume more power when opening or closing the sliding lid, theoretically up to 2000 milliamps (2 amps) but we have never seen the servo consume more than around 750 milliamps.

Usage cases

We've divided battery-powered CrowBox configurations into two categories, covering what we believe are the most common requirements.

Short term battery power

This is probably the configuration most users will be interested in. Short term battery power describes a CrowBox installed on or around your home, school or workplace, or put simply, any place where the operator has easy access to the CrowBox and visits the CrowBox frequently to check up on it.

We call this 'short term' power because it will be necessary to swap the CrowBox's batteries every few days or so, depending on the size of the battery used.

As we'll discuss in a moment, we suggest the use of a USB power bank to power a CrowBox on short term power.

Long term battery power

Long term battery power would be suitable for a CrowBox which is installed somewhere that is not readily accessible to the operator and is not checked on very often. This type of installation requires a larger battery and may employ solar panels or other strategies to extend the working life of the battery.

A CrowBox running on 'long term' battery power might be deployed in the middle of the woods or at the far edge of large field or farm.

For now this article won't discuss long term power options in further detail. This is mainly because we are unaware of any users who require long term battery power. But the ideal solution probably involves the use of a large 12 volt battery such as an automobile or motorcycle battery. A DC-to-DC buck converter is also required to step the battery's 12 volt output down to 5 volts, which is the voltage the CrowBox requires.

Short Term Power Plan

This section describes what you'll need to do in order to convert a CrowBox to run on short term power.

Choosing a power bank

Due to the enormous popularity of smartphones, tablets and other devices which are recharged through a USB cable, portable batteries with USB ports (USB power banks) are also extremely common and relatively inexpensive. As long as you choose a USB power bank that meets the requirements listed below, you will find it to be an effective and easy-to-use power source.

Power Bank Capacity

USB Power Bank capacity is expressed in milliamp-hours, or mAh. For our application, 5000 mAh is the minimum you should consider. High-capacity power banks may provide 30,000 mAh or more.

Capacity matters because it determines how long your CrowBox can run off of the power bank before the power bank must be removed and recharged. Here's how you figure out how long a CrowBox will run on a given power bank:

[Hours of continuous operation] = [power bank capacity in mAh] / 50

This computation assumes the CrowBox is idle most of the time. Depending on the level of activity, particularly how many times the sliding lid is opened and closed each day, the power bank may need to be recharged sooner.

So- If you are considering a 5000 mAh power bank, a CrowBox will run for about 100 hours on a full charge (5000/50 = 100 hours). 100 hours divided by 24 comes out to about 4.166 days of operation on a single charge. To be safe, it would be best to recharge the battery about every three days. This should account for the additional power consumed by the CrowBox opening and closing several times a day as well as trace power consumed by the internal circuitry of the power bank as well as any indicator lights the power bank may have.

kit/mod_battery_power.1547943957.txt.gz · Last modified: 2019/01/19 16:25 by steve