Do you know someone with the same type laptop (or maybe same series)? Then you can change batteries and charge the battery in the other laptop.
A few tips to make battery time longer:
- Go to a cool location (laptop has to cool less thus saving energy)
- Dim the light of the screen as far as possible and use the laptop in the dark (this may save the most).
- Stop all programs that use much energy, like download programs and scheduled maintenance (like defragmentation). They can do their job when energy is back!
Hope this is useful.