Portable USB Charger - Beginner's Early Project - Page 1
Forum section: electronics / projects

author: Kernel
author_rank: Contributor
timestamp: July 26, 2013, 03:04:17 pm
content: My first project will be a battery powered portable USB charger for use with my mobile phone which when running the 3G hardware under load to listen to music off YouTube runs out of battery rather quickly, and I'm way too much of a cheap arse to spend three digits on a phone with decent battery life. I've already spent 8 whole dollars on an extended battery pack, after all.So I will build myself a battery charger or ten. The idea is to make something way cooler than the ones you get out of those new vending machines for $30, at less of the price, that you can fit 5 of in your pocket easily, running off of either AA batteries because they are available everywhere or a compact high mAh rating lithium battery which I could scavenge out of an old high end mobile phone. After all, they have them just sitting on the counter in a basket at Gold Buyers. Bonus points for building something which can be switched between the two with hot-swappable packs, even more bonus points for building something which plugs into a powered USB port for charging the batteries.This is the board, or one like it, that I will use:http://www.ebay.com.au/itm/10PCS-Mini-USB-5V-1A-Lithium-Battery-Charging-Board-Charger-Module-Hotsell-FV8-/130872106099?pt=AU_B_I_Electrical_Test_Equipment&hash=item1e7895dc73&_uhb=1Anyone know of a higher quality board? Could I even build my own out of higher quality components copying the design directly, it looks pretty easy? Hell, I could even order 10 lots of each of the higher quality equivalent components, and replace the components of the boards directly. I will then be a good SMD solderer, woot.It seems plainly obvious that it is, but I gotta ask: Is this a good first project for a beginner?

author: c4757p
author_rank: Super Contributor
timestamp: July 26, 2013, 03:14:11 pm
content: That's an actual battery charger board, meant to connect to a battery. A USB "charger" isn't really a charger, just a 5V power supply. Try something more likethis.But I don't get what the "project" is. It's already built!

author: mariush
author_rank: Super Contributor
timestamp: July 26, 2013, 03:37:43 pm
content: As c4 says... that's board is about charging lithium batteries using the usb port as power source.You want to make a 5v usb power supply, which would basically allow you to connect a usb cable to it and to a phone and give the phone the power it needs.If you want to use AA batteries to charge a phone, you basically need a boost regulator, which would take 1.5-3v and raise it up to 4.5-5v (which is what the phone expects to get from usb jack).For example, you might want to have a look at LT1308 :http://cds.linear.com/docs/en/datasheet/1308abfb.pdfUse the SEPIC design in the datasheet at page 10 and you'll get 5v @ 0.5A from 3-10v so you can use 2-4 AA batteries to keep the phone happy for a long time.5v @ 0.5A is the standard power for usb ports on the computer ... with the plain boost design on another page in the datasheet this chip will give you up to about 400mA at 5v from 1.5v but with more input voltage it can go up to about 1A.You may have to put a few resistors on the data pins on the usb jack to trick the phone into thinking the charger can do 1A or more... see the mintyboost page about choosing the resistors to tell iphones that the charger is capable of a particular power :http://learn.adafruit.com/minty-boost/icharging

author: Kernel
author_rank: Contributor
timestamp: July 27, 2013, 08:15:07 am
content: Ah, I was thinking it was the other way around, that the board was for taking batteries and putting power to the USB port... since it's actually a battery charger that gets its power from USB I think I'll get it anyway, or build my own, because I want to be able to plug my portable charger into somewhere using USB and charge the internal lithium battery that I will install as well as having the option of AA batteries.A board like the LT1308 looks like a goer, might try building one and see how it goes. If it's a success I will build a few.Think I'll follow your advice and place those resistors on the data pins to keep it versatile. Maybe I'll save somebody's day by charging their iphone...

author: amyk
author_rank: Super Contributor
timestamp: July 27, 2013, 09:26:31 am
content: In other words you're making a battery-powered battery charger?

author: Legit-Design
author_rank: Frequent Contributor
timestamp: July 27, 2013, 11:09:25 am
content: http://www.buyincoins.com/item/28091.htmlHave one of these, I could get my choosing on the cells. None of this cheap lipo crap.from ebay:http://www.ebay.com/itm/18650-5V-1A-Box-portable-type-Mobile-Power-Supply-USB-Battery-Charger-/110830235797?pt=AU_MobilePhoneAccessories&hash=item19cdff3095http://www.ebay.com/itm/Portable-5V-1A-Mobile-Power-Supply-18650-Battery-USB-Charger-Box-/171018098621?pt=LH_DefaultDomain_0&var=&hash=item27d17917bd(2 cell)http://www.ebay.com/itm/New-5V-in-2A-out-1A-Mobile-Travel-PowerSupply-18650-Battery-USB-Charger-Box-/150931732401?pt=Battery_Chargers&hash=item23243b77b1http://www.ebay.com/itm/2-5A-Output-5V-Mobile-Portable-Power-Supply-USB-Battery-Charger-18650-Box-NEW-/281042312959?pt=AU_Electronics_Batteries_Chargers&hash=item416f6d5eff(4 cell)Low voltage cut off at 3.2V on mine, charges to 4.2V. I've had mine for about an year now. No problems whatsoever.Good quality HUGE 18650 cells are readily available thanks to flashlight enthusiasts.With four (4) 3400mAh I could get ~50Wh of capacity in batteries, minus efficiency and conversion, but still alot for something that fits in a pocket.If I rolled my own, it would have to do something more.

author: Kernel
author_rank: Contributor
timestamp: July 30, 2013, 10:24:09 am
content: Hey I saw those but didn't notice they had the functionality of charging the batteries inside of them, suppose it would be silly not to have that wouldn't it?The one I wanted to make will have an LED indication of the internal battery charge level. Maybe I could add this in to one of these little units, it's basically just a voltmeter.

author: brainwash
author_rank: Frequent Contributor
timestamp: July 30, 2013, 02:11:08 pm
content: For using 1-3 AA/AAA batteries (for emergencies) this might come handy:http://dx.com/p/usb-dc-1-5v-to-dc-5v-voltage-step-up-boost-module-green-143571

author: Legit-Design
author_rank: Frequent Contributor
timestamp: July 30, 2013, 03:25:57 pm
content: Quote from: Kernel on July 30, 2013, 10:24:09 amThe one pictured above already has three leds to indicate charge level, small momentary tac switch turns that function on so it will not drain battery unnecessarily. Those three tiny leds on the side with push button on top of them, leds are blue,green and red. When red led doesn't turn anymore the unit is almost out of charge. With the usb output turned on by that big red rocker switch, the flashlight led comes on dimmed, when you press that small push button it will come on quite brightly to act as a flashlight.When charging it via usb/other small led next to the mini usb port comes on red, when it has charged full it will turn to green.One thing to note about it, is that mine 'passed' even airport security check. I didn't even remember I had it in my backpack, the security guy told me that there was something in my backpack he wanted to maybe see, I know I forgot to put my fluids separately and told him that, then he just let it pass without even checking. But I guess they just want to know there isn't a fire hazard from batteries shorting out.I wouldn't try to go through airport security with one of these duct tape thingies:Note:Not my projecthttp://www.ruuvipenkki.fi/foorumi/viewtopic.php?f=15&t=1053finnish forum, google translate link:http://translate.google.com/translate?sl=fi&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.ruuvipenkki.fi%2Ffoorumi%2Fviewtopic.php%3Ff%3D15%26t%3D1053pommi = bombduct tape is sometimes called 'jesus tape' in finnish because it can fix everything...