Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 74 users online :: 3 registered, 0 hidden and 71 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Solar charger idea

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.
Sponsored 
  • Author
    Message

Solar charger idea

Unread postAuthor: metalmeltr » Thu Jul 14, 2011 11:02 pm

I recently had an idea to build a solar charger for USB and car charged devices for use when camping. I am a Boy Scout and on one of our recent trips had some dead cell phones and no way to charge them.

The solar panel would be made up of cells from outdoor solar lights.
The voltage from the panels would be regulated by 7805 and 7812 voltage regulators for USB and Car outlets respectively. I am thinking about putting some sort of quick connect in between the circuit and the solar panel so that power can also be supplied though batteries, maybe a wind turbine, or a wall transformer.
  • 0

Attachments
solar charger scematic.JPG
solar charger scematic.JPG (38.01 KiB) Viewed 790 times

metalmeltr
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 426
Joined: Thu Dec 18, 2008 3:42 pm
Location: united states
Reputation: 0

Unread postAuthor: Zeus » Thu Jul 14, 2011 11:16 pm

Those solar panels give very little current, the design is fine, but unless it's only one phone a day, it won't do a lot.

Now if you left the charging circuit and batteries from the solar lights, and connect the batteries as per the schematic, you'll be on to something good.
  • 0

/sarcasm, /hyperbole
User avatar
Zeus
Major General
Major General
 
Posts: 1422
Joined: Tue Oct 27, 2009 7:34 pm
Location: 'Straya, C*nt
Reputation: 2

Unread postAuthor: metalmeltr » Thu Jul 14, 2011 11:19 pm

I knew that the panel can't provide much current. Are you sugesting that the panels charge the batteries and then the batteries charge devices?

Potential devices to charge
Cell phones
Ipods
Ipad
  • 0


metalmeltr
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 426
Joined: Thu Dec 18, 2008 3:42 pm
Location: united states
Reputation: 0

Unread postAuthor: irisher » Thu Jul 14, 2011 11:25 pm

A true boy scout does not need a cell phone. :lol:
  • 0

Si vis pacem , constructum tartufoli ornamentum
User avatar
irisher
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 420
Joined: Mon Dec 29, 2008 2:53 am
Reputation: 0

Unread postAuthor: Zeus » Thu Jul 14, 2011 11:31 pm

Indeed I am, if you allow it to charge all the time, then draw on it when needed, it eliminates dependance on the sun, presuming it isn't used frivolously.

Any good?
  • 0

/sarcasm, /hyperbole
User avatar
Zeus
Major General
Major General
 
Posts: 1422
Joined: Tue Oct 27, 2009 7:34 pm
Location: 'Straya, C*nt
Reputation: 2

Unread postAuthor: metalmeltr » Thu Jul 14, 2011 11:38 pm

irisher wrote:A true boy scout does not need a cell phone. :lol:
We are all adicted to our scoutmaster's iPad! lol If it runs out of batteries who knows what will happen!

At 15 my electronics experience is limited to the electronics merit badge, tearing things apart and internet research so any guidance on the charging circuitry would be greatly appreciated.
  • 0


metalmeltr
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 426
Joined: Thu Dec 18, 2008 3:42 pm
Location: united states
Reputation: 0

Unread postAuthor: noname » Thu Jul 14, 2011 11:55 pm

At my Boy Scout outings were were always finding better things to do, like shooting potatoes! Or batteries!

If you're on an outing, you should be taking advantage of the wilderness and doing more outdoorsy things than messing around on an iPad, which you can have any day you want. I'll assume you're an older guy in your troop, so why not use your "cool old teenager" status to get the age < 13 mini-scouts interested in the various awesome aspects you can find on any outing? :wink:


Edit: Still a cool project though, I guess it could probably be of some practical use sometime.
  • 0

User avatar
noname
Lieutenant General
Lieutenant General
 
Posts: 2699
Joined: Mon Apr 10, 2006 9:19 pm
Location: Bay Area, CA
Country: United States (us)
Reputation: 9

Sponsored

Sponsor
 


Unread postAuthor: metalmeltr » Fri Jul 15, 2011 12:02 am

This year at summer camp the Ipad was the "cool new toy". It has yet to be diminished of this status. We have plenty of outdoor activities within the troop. One of the main attractions being my advanced combustion cannon. This is just meant to maintain batteries for emergencies and to power devices in case of emergency.
  • 0


metalmeltr
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 426
Joined: Thu Dec 18, 2008 3:42 pm
Location: united states
Reputation: 0

Unread postAuthor: Technician1002 » Fri Jul 15, 2011 12:05 am

Before you build it, serious consideration must be given to the power requirements. Many cell phones will draw a fixed charging current for the high rate charge, then when the battery is up, shuts off and announces the battery is charged. This current can exceed 500 ma on some phones.

The soler chargers on the other hand don't put out nearly that much current, so the phone would attempt to charge, then the overloaded solar source would be a voltage crash and the charging circuit would detect that as a power failure and shut down. In short, it won't charge.

If you keep the solar cells and the light batteries together, then the lights can charge their batteries and then you can provide a short term high current load such as charging a phone.

In a situation where power is scarce, it makes little sense to throw over half of the power away as heat. The regulator you have chosen is an Analog regulator. It would take the ~15 volts in the charged solar lights batteries and turn 2/3 of that into heat as it drops 10 volts on the regulator and 5 volts on the charging phone.

Find a high efficiency switch mode power adapter instead. They work by dropping the voltage but generating very little heat. Instead of taking in 15 volts at 1/2 amp (7 watts) and putting out 5 volts at 1/2 amp (2.5 watts) with 5 watts used to heat the regulator IC, the switching regulator takes in about 2.7 watts and puts out 2.5 watts at 5 volts and generating 0.2 watts of heat in the regulator (none are 100% efficient 80-90% is typical). This gives over twice the charge into the phone for the same amount of solar power.

For 12 volts I would toss the 12 volt regulator. A car charging system when running is about 14 volts. The ~15 volts on the solar battery pack will not cause any problems with most electronics designed to run off a car lighter socket.

More info on the charging requirements for an iPad is on this page;
http://www.neowin.net/news/the-ipad039s-usb-charging-caveat

There are a couple of things to note, the fast charge takes 10 Watts or 2 Amps of power for the fast charge. To get the iPad to take a fast charge the USB port must communicate with the iPad that it can provide high power. Same for the other two power levels. Normal high power at 500mA (2.5 watts) or 100 mA for low power. Just jacking into a powered USB jack with 5 volts and no communication will probably place it in the slow charge mode.

Many of the solar lights charge their internal batteries at under 20 mA. (0.02 Amps) Feeding an iPad looking for 2, 0.5, or 0.1 Amps will show the difficulty of using the solar lights directly without stored energy.

In a nutshell you will need to collect 50 hours of direct sunlight charge in batteries to provide 1/2 hour of 2 Amp current to the iPad.

Saved and used power is measured in Amp Hours for charging batteries and Watt Hours for measuring power use. Two hours of high current iPad charging (10 Watt rate) is 20 Watt Hours.

A solar light that charges a 300 mAH battery at 3.6 volts has saved a total of 1.08 Watt Hours during the entire day. A bank of 20 of the solar lights would be the bare minimum to give the I pad a 2 hour quick charge not counting loss in the regulator.

Check your solar lights to find the battery capacity. That will give you an idea of the total maximum amount of power they could possibly collect in a day. They of course run down completely at night.

For charging phones (not an iPad) a 3 watt 5 volt panel is recommended as it will provide the required 2.5 watts many phones require. This is a typical panel made for this application;
http://www.google.com/products/catalog?hl=en&xhr=t&q=5+volt+solar+panel&cp=9&bav=on.2,or.r_gc.r_pw.&biw=922&bih=428&um=1&ie=UTF-8&tbm=shop&cid=16766008426046975426&sa=X&ei=CtIfTqyjEIeisQOIsY09&sqi=2&ved=0CF8Q8wIwAQ
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: Crna Legija » Fri Jul 15, 2011 2:09 am

you need to get your smoke signal on
  • 0

'' To alcohol... The cause of, and solution to, all of life's problems.”
--Homer Simpson

Add me on ps3: wannafuk, 8/11/11 cant wait
User avatar
Crna Legija
Major General
Major General
 
Posts: 2333
Joined: Sun Jul 20, 2008 5:14 am
Location: australia
Reputation: 0

Return to Non-Spudgun Related Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Yahoo [Bot]

Reputation System ©'