Emergency Mobile charger help..

[yusuf]

Hello friends...
I have seald lead acid battery.. And its rating is 4v , 1Ah..
I have nokia cell phone in which there 3.7V , 1200 mah battery.. I want to use my lead acid battery for charging my mobile in emergency..
Please help.

 

[4pyros]

I have seald lead acid battery.. And its rating is 4v , 1Ah..

I did not know you can have a 4 volt sealed lead acid battery. It should be 1.5 volts per cell.
Have you looked a low drop out regulaters?
What are the specs for the phone?

 

[Diver300]

I did not know you can have a 4 volt sealed lead acid battery. It should be 1.5 volts per cell.
Have you looked a low drop out regulaters?
What are the specs for the phone?

Lead-acid batteries are 2 V per cell, so 4 volts is just two cells.

 

[4pyros]

Lead-acid batteries are 2 V per cell, so 4 volts is just two cells.

Opps......

 

[Sceadwian]

4pyros, math errors happen to the best of us! And far more frequently to people like me =)

yusuf, there is no simple way to do what you want, it's not very practical either considering the Lithium cell actually has more energy storage capacity than the lead acid pack does.

To make a practical emergency recharger the simplest method is to use a higher voltage battery with a regulator and set the regulator to whatever the phone chargers voltage is and allow it to charge itself from this supply.

You could probably directly wire the lead acid battery to the Lithium cell with a current limit resistor can get SOME kind of charge into the Lithium cell but I wouldn't image it would be enough to be useful, and the voltage dip of a lead acid pack during discharge would quickly drop to the point where it wouldn't be able to charge the Lithium cell LONG before it reached a full charge state.