# 5.7v/400mA from just 1.5v AA BATTERY !!!

Discussion in 'General Electronics Chat' started by mkbutan, May 11, 2011.

1. ### mkbutan Thread Starter Senior Member

Sep 30, 2008
270
16
Any circuit which deliver the voltage & current for the Mobile Battery (4.5v) charging with just one AA type (1.2v/1.5v) Battery?
Specification:
Maximum Current：400mA
Output Voltage：5.7V+5%
Power source 1 X AA Battery.

Suits to charge Mobile phone, digital camera, PDA, MP3, MP4, etc.

This Blue Emergency Battery Charger for Mobile Phone is been soled by the e-bay
( http://cgi.ebay.com/Blue-Emergency-...117129?pt=PDA_Accessories&hash=item3f0133e249 )

I don't think so it can deliver 5.7v/400mA with just one 1.2v 0r 1.5v AA battery!!!!!!!!!!

2. ### Jaguarjoe Active Member

Apr 7, 2010
770
90
An Alkaline AA cell has about 2.6wh of energy.
5.7v @ 400ma is 2.3w.
2.6wh/2.3w = 1 hour and 8 minutes of life @ 100% conversion efficiency.
At a more realistic 85%, you'll get 58 minutes.

mkbutan likes this.
3. ### mkbutan Thread Starter Senior Member

Sep 30, 2008
270
16

But AA/AAA Battery is about 1.5v
then how it can charge 4.5v Mobile battery?
pl. explain with any CKT.

Dec 26, 2010
2,147
298
By means of a boost converter. http://en.wikipedia.org/wiki/Boost_converter

There is nothing very special about these gadgets, but note that you won't get much of a charge out of a single AA cell. In an emergency though, with no access to power I suppose you might be able to charge a phone enough to make a call or two.

5. ### PackratKing Well-Known Member

Jul 13, 2008
850
215
The efficiency is dismal at best, though it is possible to do

Witness the disposable [ film ] camera, that employs a single AA battery to power its flash, which charges a capacitor up to a 200μf - 350 Volts dc to run the flash.
They recycle to be able to fire in roughly 30 seconds, not to mention the battery is still marginally useable after the film is all exposed...........

You will have to do your own research based on your electronic experience ?? to find and comprehend the necessary circuitry, because know this............those little camera circuits are downright deadly if handled improperly.

Last edited: May 21, 2011
6. ### mkbutan Thread Starter Senior Member

Sep 30, 2008
270
16

Flash camera's have the LCR CKT. to boost and store the energy for the capacitor to charge for the film Camera but not in mobile

7. ### PackratKing Well-Known Member

Jul 13, 2008
850
215
The camera is but one example that a single AA cell can be used for larger applications.

You will have to do your own research based on your obviously limited electronic experience ?? to find and comprehend the necessary circuitry, because know this............those little camera circuits are downright deadly if handled improperly.

Dec 26, 2010
2,147
298
The "emergency" chargers normally use a fly-back principle, typically using a little ferrite bobbin choke just a few millimetres long. Similar things are seen in little torches (flashlights) that run white LEDs off just one alkaline cell.

Apr 30, 2011
1,418
359
PackratKing likes this.
10. ### Audioguru New Member

Dec 20, 2007
9,411
895
Solar garden lights use a simple and cheap voltage stepup circuit to use a single 1.2V rechargeable battery cell to light a 3.5V white or multi-colours LED all night long.
A solar garden light is on sale this week for only \$.99.

11. ### nbw Member

May 8, 2011
36
10
I found a webpage (might have been an Instructable?) that showed how to make a stun gun out of a disposable camera - using that same HV cap you mention. So yes - be <snip> careful!

Last edited by a moderator: May 22, 2011