Power Pack from Li-ion Cells

[roltex_rohit123]

I want to build a power pack of about 4/6 Li-ion cells. This power pack could charge my cell phones and ipod when on the move. I often go for trek with my friends and someone or the other always urges for such kind of a circuit. The idea is that I would mount the Li-ion cells in a box along with the circuit and I would charge cell phones or ipod from it. I will put two inputs to charge my battery pack, one from solar cells and other from a cellphone charger. I know that Li-ion cells are dangerous to use if not handled with care so I would like to use overvoltage protection and undervoltage protection in my circuit. can anyone suggest me some ic's or schematics please?
Thanks!!!

 

[mneary]

Seiko S8232.

 

[vmsa]

There are many circuits for lithium chargers with the cheap LM317.

 

[roltex_rohit123]

Li-ion power pack

There are many circuits for lithium chargers with the cheap LM317.

I have learnt that it is very difficult to maintain Li-ion cells in terms of charging. where there are special algorithms to charge them, they are potential bombs if abused. so LM317 isnt sufficient to charge the cells. just bulk charging shortens battery life, i want to extend battery life not shorten it. so i am trying to build an advanced and smart circuit.