It wouldn't change your seat height, from pedals to seat, but it would lower your bar about an inch.
To change your pedal to seat height, shorter cranks would make the bottom of the stroke closer to the seat. And choose a seat that has a low profile, if yours is tall from the rails to the top of the seat.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.