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Mobile charging 24/7 with timer circuit? (30min/24hr)

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altainta

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How to keep charging Mobile 24/7 with timer ?


Hi i am hobbyist in electronic but i don't know electronics much.
In my application i will have to leave the Mobile / cellphone charger ON for 24/7 in the motorcycle. My bike contain 12v battery. so i would like to know

The cellphone (Nokia 3310 LI ION battery 3.6v)will be connected with a car charger and applied a 7805 which will keep the voltage 5v (because the car charger

was outputting 8v dc while i tested it on home ac adaptor) and will go to 12v Battery of the bike..

1) I want the mobile to get charging of 30min / from 24hours (should i increase or decrease this time ?).
2) It should not overcharge (Exception)
3) Where should i place the circuit on Position A or B ? (refer to he image plz)
4) How to reduce the 5V further for a Good 3.8v Dc (for good battery life). If resistor than which value and on which node (positive or negative)
5) Will i have to use PICAXE ic ? is the right way ? if yes than how because i never used PICAXE before...


I thought putting a alarm clock but it will be bulky better would be using a circuit design which will do the same as the alarm clock.


Even if the circuit is not possible atleast tell me how to charge the mobile if the circuit is triped because of alaram clock for atleast 30min...



I thought of using 555 timer or 556 or other options but never used that....Please do guide...
 

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Why don't you just open the 12/8V mobile charger, change one resistor, and turn it into a 12/5V charger?

Most of the the mobile chargers I have around here use a SMPS based on this chip: 34063. Look at the suggested circuit Fig 11, Step-Down Converter. All you need to do is change R1/R2 to convert this to a 5V charger.

As to leaving it connected to the motorcycle 24/7, that is up to how sophisticated the charging circuit inside the cell phone is? Since it has processor code to implement the charging algorithm, it should be smart enough not to overcharge if left on overnight.

If you have doubts about how smart your cell phone is, read this thread.
 
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A big cell phone manufacturer like Nokia would be sued if the charger circuit in the phone did not turn off the charging of the Lithium cell when it is fully charged because a Lithium cell becomes very dangerous if it is overcharged and might catch on fire.

Simply see the charging indication on the phone turn off when the cell is fully charged.
 
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