Li-ion Solar Charging circuit

[ripper121]

Hi,
I need a charging circuit for a 7.4V Li-ion Cell and a 14V 300mA (measured in the sun so i think its a 12V Panel).

I read many about the LM317 bad and good, but i dont know what IC and circuit I should use.

I need a easy and cheap circuit for charging a 7.4V Li-ion Cell with a 12V Panel and optionally external Power.

Thanks

[Simon]

You will need a proper charging circuit for Li-ion as otherwise your battery can become a hand grenade. You'd best use something that is based on a switchmode design to maximise efficiency as the LM317 just turns power into heat and wastes it.

[ripper121]

Yes i know read this many time before.
But do you have a good IC and schematic for me?

[Simon]

look for a li-ion charge controller IC, it may do the switchmode bit itself or you may need to put a SMPS in front of it.

[ripper121]

What do i have to change in this Circuit to fit my App.

In 12V out 7.4V.