Buck, Boost or Buck-Boost converter???

[aabundle]

Hey Guys,

Im currently making a solar powered battery charger. Its for a Li-ion battey so the max voltage it should be charged upto is 4.2V and it has a capacity of 2600mAh. Im contructing the solar panel myself so i can make it under the 4.2 volts or over.

I am probably going to make a buck-boost converter to take into consideration when the voltage is under or over my desired level... BUT

I was just wondering from a design simplicity standpoint is it better to make a boost converter instead of a buck-boost. Because then i would know that the volatge is always under.

 

[Grossel]

It depends on expected voltage from solar panel. Also that voltage will vary as the load vary.

 

[MrAl]

Hello there,

The buck circuit is the most efficient and the most stable. I'd go with that since you can make the solar panel voltage whatever you want it to be. Although it's better to have the input and output voltage as close to the same as possible, you should make the panel voltage taking into consideration any loading while operating. That means it has to be a bit higher than the output is going to be while the cell is charging.
You might want to look into max power tracking too where you get the most power out of the array for a given level of sunlight.

 

[aabundle]

Thanks MrAl.

Hey Grossel i can make the voltage whatever i need (in steps of 0.5V).