Emergency Charger for Cell phone

[bk3e]

Dear All,
I need schematic of Emergency Charger for cell phone using a 1.5V AA battery. Can you help me. I also tested some circuit using boost Dc-Dc converter but It was not successful. thanks all.

[tAhm1D]

Hi,
You could try this  :

[Parmin]

Maxim MAX1674 , 75 , 76

# 94% Efficient at 200mA Output Current
# 16µA Quiescent Supply Current
# Internal Synchronous Rectifier (no external diode)
# 0.1µA Logic-Controlled Shutdown
# LBI/LBO Low-Battery Detector
# Selectable Current Limit for Reduced Ripple
# Low-Noise, Anti-Ringing Feature (MAX1676)
# 8-Pin and 10-Pin µMAX Packages

Complete specs and samples available at Maxim's site.

[tAhm1D]

Hi,
You can try this as well:

[tAhm1D]

Hi, another easy boost circuit you could try:

[wyatt]

This one uses 2 cells:

http://www.ladyada.net/make/mintyboost/index.html
 

[tAhm1D]

Hi, Another one:

[Parmin]

if the 1N4148 changed to a schottky diode, then it will work a lot more efficient.
the circuit only could supply very low amperage ~75mA or less..

[Jehan]

Very difficult using single 1.5 volt cell, typical charging current will be in the range of 600ma for a cell phone battery, even if you are able to convert 1.5 volt to 5 volt the typical efficiency will be in the range of 70%, this means you have only 70% of the available energy of the original battery power, and definitely an AA cell will not be able to deliver 600 milli amp @ 5 volt ie. around 3 watt of power which correspond to around 2.8 amp at 1.35 volt ( 3.9 watt including efficiency loss)  which the AA battery will not source.

[tAhm1D]

Very difficult using single 1.5 volt cell, typical charging current will be in the range of 600ma for a cell phone battery, even if you are able to convert 1.5 volt to 5 volt the typical efficiency will be in the range of 70%, this means you have only 70% of the available energy of the original battery power, and definitely an AA cell will not be able to deliver 600 milli amp @ 5 volt ie. around 3 watt of power which correspond to around 2.8 amp at 1.35 volt ( 3.9 watt including efficiency loss)  which the AA battery will not source.

If the circuit requires 2.8A, this is possible for the AA battery to source as I've procured a pair of SONY 1.5v 4.8Ah cells. So with modern technology and latest products, it is very much possible to source sufficient current from a 1.5v AA cell.

[tAhm1D]

Hi,
With high power AA battery, following circuit can be tried for high power to charge cell phone battery quickly.

[Jehan]

If the circuit requires 2.8A, this is possible for the AA battery to source as I've procured a pair of SONY 1.5v 4.8Ah cells. So with modern technology and latest products, it is very much possible to source sufficient current from a 1.5v AA cell.

I thought it had to be charged from   AA alkaline non rechargeable duracell  type of battery, if it is rechargeable Nimh or Lithium, yes it is possible, but take One care, see that the failed mosfet of the DC-Dc Converter does not cause a input short circuit, always use a small fuse in the input as there can be fire accidents with a shorted Nimh/lithium Batterry, the packaged type of cells will have inbuilt electronic based protection but, some of the raw individual cells will not have this protection.