I came up with this idea the other day at work (i have a very boring job) so I drew up a rough diagram. I am hoping for some input on this idea, and maybe even have some one draw a better diagram for me that includes the 5v regulator. Here is the diagram, I will explain it as best as i can below the pic. S1,S2,S3,S4,and SM are 2 position selector switches (one side makes one set of contacts, the other side makes another set of contacts). P1 and P2 indicate witch contact is being made. Batt A and Batt B are self explanatory. In this set up I am hoping to go from 2 batts running in parallel at 3.7v (P1 on the switches) to running 5v (P2 on the switches). The main outs from S1 and S3 would then run to the 5v regulator. Here is a quick run through of what each switch will do S1/P1) Batt A & Batt B + S2/P1) No contact S3/P1) Batt A & Batt B - S4/P1) Green LED (to indicate 3.7v is set) S1/P2) Batt A + S2/P2) Batt B + to Batt A - S3/P2) Batt B - S4/P2) Red LED (to indicate 5v set) SM) Master on/off switch All 4 selector switches would be tied together so that they would not be abel to be switched individually (to avoid any chance of explosion). I hope i have explained my self well enough. Any advise, criticism, or better diagrams are greatly welcomed.