state of rechargeable battery

[Rajashri.Shevale]

I have Lipo-Battery. I want to charge it with solar panel as well as through AC adapter. I want my battery will charge with solar panel when sunlight is coming otherwise it will automatically switch to AC adapter. in this system i want my circuit will continuously check the state of battery. then to acheive this what should i do in my circuit.

 

[kam1787]

Maybe I am too simplistic at thinking you are being too complicated....

If you can 'break' the adapter/charger - where the DC feeds the charger - I would simply put them in parallel with isolating diodes

 

[Audioguru]

A Li-Po battery is dangerous and can expode or catch on fire if it is not charged and discharged correctly.
Use a battery charger IC designed to charge a Li-Po battery.

A Li-Po battery cell voltage is a minimum of 3.2V when its load should be disconnected, is a maximum of 4.20V when it is fully charged and its charging current has reduced to a small amount and is an average voltage of 3.7V during a discharge. When it is charging its voltage rises slowly to 4.20V where the charger should limit the voltage but it is only about 70% charged. You must measure the charging voltage AND the charging current to determine the state of charge. You might use the discharging voltage to determine how much charge remains.