Hello,
I'm struggling with a problem please help me out of this..

I have four 3.7 volt Li-ion Cells and want to charge them in parallel (For my convenience) and take output from them in series.
Can anyone suggest a circuit.
It will be good if a circuit can do both simultaneously but it is not necessary

 

A parallel AND series arrangement cannot be done
while charging and working a load.
No circuit can accomplish that feat.

 

With relays or medium-power transistors you can reconfigure the batteries for parallel charging or series discharging and hop back and forth between the two, but as mentioned you cannot have both configurations simultaneously. To do this with relays you would need two 3PDT relays operated together as a single 6PDT relay.

ak

 

I disagree. It can be done with 4 isolated supplies. Although it might be questionable to call that parallel.

Bob

 

I did not say that my suggestion was the only thing that would work. Of course there are configurations other than the one I described. However, I think one supply, four charge controllers, and the relays or transistors will cost less than 4 smaller supplies and the same 4 charge controllers. Plus, we don't know if the power source for charging is AC, DC, or non-isolated DC that shares GND with the system power output. The relay configuration doesn't care.

ak

 

Thank you guys ..

 

The similar question here - Charge Several Lithium Cells.