Schedule

Schedule

Wednesday, April 1

1427911200 Windows Weekly
1427918400 This Week in Google
1427929200 Tech News 2Night
1427931000 Android App Arena
1427936400 Ham Nation

Thursday, April 2

1427994000 Tech News Today
1427997600 Know How...
1428003000 Marketing Mavericks
1428008400 Home Theater Geeks
1428015600 Tech News 2Night
1428017400 The Giz Wiz

Friday, April 3

1428080400 Tech News Today
1428084000 This Week in Law
1428094800 Before You Buy
1428102000 Tech News 2Night
1428105600 Padre's Corner

Saturday, April 4

1428170400 The Tech Guy

Sunday, April 5

1428256800 The Tech Guy
1428271200 This Week in Tech

Monday, April 6

1428339600 Tech News Today
1428343200 Triangulation
1428348600 iPad Today
1428355800 Coding 101
1428361200 Tech News 2Night

Tuesday, April 7

1428426000 Tech News Today
1428429600 MacBreak Weekly
1428438600 Security Now
1428447600 Tech News 2Night
1428451200 All About Android

Wednesday, April 8

1428507000 FLOSS Weekly
1428512400 Tech News Today
1428516000 Windows Weekly
1428523200 This Week in Google
1428534000 Tech News 2Night
1428535800 Android App Arena
1428541200 Ham Nation

Thursday, April 9

1428598800 Tech News Today
1428602400 Know How...
1428607800 Marketing Mavericks
1428613200 Home Theater Geeks
1428620400 Tech News 2Night
1428622200 The Giz Wiz

Friday, April 10

1428685200 Tech News Today
1428688800 This Week in Law
1428699600 Before You Buy
1428706800 Tech News 2Night
1428710400 Padre's Corner

Most Recent Episodes

All About Android

Samsung Galaxy S6, The Chrome Stick, and Android Apps on Chrome OS!

Tech News 2Night

Microsoft Surface 3 can run Windows 10.

Security Now

Is it possible to replace a crashed hard drive when UEFI secure boot is on?

MacBreak Weekly
Episode #448: Normcore March 31st, 2015

How Tidal will affect Apple's Beats.

Tech News Today

IBM invests in the Internet of Things.

Tech News 2Night

Windows Spartan sneak peak

Coding 101
Episode #61: Carlos Souza March 30th, 2015

Learn ruby from codeschool.com and Carlos Souza

iPad Today

Tumblr, Instapaper, Crazy Gears

Triangulation
Episode #194: Meerkat March 30th, 2015

Meerkat founder Ben Rubin talks about the live-streaming mobile app.

Tech News Today

Apple Watch Edition purchasing process details emerge.

Know How... 91

F1 Turbo, Solar Powered Rasp Pi, and Goat Sim Tips

May 1 2014

Mercedes is wining F1 with a new twist on an old technology, power your Raspberry Pi with the sun, and Goat Simulator Tips.

Solar 101: Solar-Powered Pi

Materials:
Solar Panels
Charge Controller
Battery
12v to 5v (USB Charger)

Tools:
Wire Snips
Wire Strippers
Screwdrivers
Multimeter

Steps:
1. Determine the Draw of your Device(s)
2. Size your Battery
3. Calculate your Solar Panel Needs
4. Choose your Controller
5. Wire it!

The Draw of your Devices:
* If you're building for a house, you can look at your electricity bill for the past 12 months. That gives you a good indication of your total usage as well as your high and low usage months.
* For medium-applications, a Kill-O-Watt works well, but it has a large margin for error, especially when dealing with smaller devices
* If you're building for a small device, check the specs of the device(s) you want to power.
- A spec sheet is a good place to start
- Remember that you must also account for the inefficiency of any charging unit

A Raspberry Pie pulls 700 mA of current at 5 volts at maximum power. (It pulls 300mA at idle)

Watts = Volts * Amps
- W=VA
- West Virginia

That means the RasPi draws 700mA at 5volts, or 3.5 Watt/Hours at maximum load.
** We need to supply the RasPi with 84 Watt/Hours of power per day.

Size your Battery
You need a battery that will support your application.
* Your typically want a battery that can support your device(s) for an acceptable amount of time, assuming that there will be days when your solar panels are completely ineffective.
* For an application like the Raspberry Pi, since it doesn't draw that much, I wanted to design a system that could go 2 days without ANY solar power input.
- Since the daily draw of a RasPi is a maximum of 84 Watt/Hours a day, I need at least 168 Watt/Hours of storage.
* Most small-application solar charge regulators work at 12 or 24 volts. I chose 2 x 12v 8Ah battery that will give me 192 Watt/Hours of storage

Make SURE to get a deep-cycle battery. If you don't you'll quickly find that your batteries don't provide their rated power because of the memory effect. (Most batteries are NOT designed to run all the way down.

Calculate your Solar Panel Needs:
You need to know (1. Draw of your devices) and (2. PEAK Hours in your Location)

Peak Sun Hours is the equivalent number of hours per day when solar irradiance averages 1,000watts per square meter.
- You want to know the amount of sun energy you'll receive per day on the WORST MONTHS of the year.
- Included is a "worst case scenario" solar map based on data from the past 30 years.

* You can use this information to determine how much panel you need.
* In our example. We know that our draw will be 84 Watt/Hours a day
- We need a panel that can generate 84 Watt/Hours a day with MY Peak Hour value
- We also need to keep in mind the charging of the battery. The more power OVER than number, the faster I'll charge a depleted battery.
- I also like to give myself a margin of safety to account for inefficiencies. (I use 20%)

In my location in San Francisco, the worst-case Peak Sun value is 3.6
- That means I can expect MAXIMUM solar exposure for a minimum of 3.6 hours a day
- I have two 90Wh batteries to fill and 84Wh of draw, but only 12.6 Watt/hours of that draw (3.6 hours x 3.5 Watts/hour) will come from the solar panel, the rest will come from the battery.
- I also want to account for the inefficiencies of the system. (I'll add in another 40W/h)
- That means I want a Solar Array that can give me ~240W/H in those 3.6 hours of Peak Sun.

I actually have a 240W/H solar panel… which means I am WAY over supplying the Pi!

Choose your Solar Charger
- You need a unit that will support the total wattage of your Solar Panels AND the total draw of your electronic devices.

Connect with us!
Don't forget to check out our large library of projects on this site. If you want to search for a topic, try this custom search engine. Also, check out our transcripts.
- Google+ Community at gplus.to/twitkh
- Tweet at us at @padresj and @Cranky_Hippo
- Email us at knowhow@twit.tv