Constant voltage regulator to charge lithium ion cell

[Kimly]

Hi All, I am very new to electronics so please excuse my stupid questions.
I am trying to design a solar powered light to assist people in rural areas who don't have electricity. I have the following components, a solar panel which can put out 170mA and 5.5V at max performance. I have a lithium ion cell which is 4.2v 2600mA and an LED which offers max performance at 3.7v and 350mA.

What I need is a voltage regulator which will allow the lithium cell to be charged at a constant 4.2v. Also, it must not be over charged.

I also need a protection circuit which must prevent over discharge of the lithium ion cell by the LED. (this I think I may be able to arrange with the purchase of the Lithium ion cell)

any help will be appreciated
thanks

[Jerry]

You would not want to charge a lithium ion battery with just a voltage regulator.  The voltage regulator just provides you with a constant voltage.  It does not regulate the current and more importantly it will not stop the charging process once the battery is fully charged.  Your battery could be damaged is you charge it too long or if you charge it with a current that is too high.  Also, when you have the battery in use, you do not want to alow the battery to discharge too far.  If you do, it could be damaged or reach the point where it would not take a charge any more.

Watch the video below.  It's very informative and helpful.