with Popolu Step-up Regulator U3V12F5.

But Very Importend, use one capacitor 100 uF, i destroy before one regulator, i dont know why, but with a capacitor (vin + gnd) works very well.

i builed in a swither between accu and regulator. i want charge the accu with a palm inductions charger and i dont know how it will handle with connectet regulator.