Thanx a ton.. Now one more question.. How do i control the current that is flowing out from the charged battery to the Mobile Phone. i.e the discharge speed? I heard that a rapid rate of discharge will also blow up the battery or make it completely useless...
And u've given 9v as the i/p supply but actually the supply will be a lot less at around 5v...
Can i use the same circuit with a different IC or do i have to change it?
And i'l also like to know the answer to Mr.Hero9999's question too...
Hello again,
Are you saying you also want to control the charge from the battery to the phone?
The charger is made just for charging, that's about it. What you do with it after that
is up to you.
The question of what happens when an Li-ion cell is charged indefinitely comes up now
and then. The answer is a bit unclear, but the main point is that Li-ion batteries should
NEVER be charged and then left alone for ANY time length. The reason for this is because
most problems occur during the charge period. That means you CAN NOT leave the cell
alone regardless of what charger you are using, so you can simply remove the cell when
it is done charging. You can calculate the time required if you like and then take it off,
or include the blue LED and that will tell you.
What happens to the current in chargers like this when the cell gets charged is that the
current reduces lower and lower, until the output current is almost nothing at all.
Typically it goes down to 50ma, then 40ma, then 20ma, then 10ma, then 5ma, and it
will remain at some low current like that for some time. The cell does not explode or
catch fire though, as the way these circuits are connected as the cell voltage rises the
current decreases more and more, so that the final voltage can never get past the
4.200 volt level no matter how long you leave it on charge.
It's always still a good idea however to take it off charge at something like C/10, so
keep that in mind, and also NEVER leave it alone and go away.
If you have any doubts about any chargers, then dont build one and simply buy one
off the web. There are many out there offered for reasonable prices.