Only three options I would consider -
1. Genuine Yaesu battery pack from hamradio.com
2. Any aftetmarket pack that batteriesamerica.com offers
3 Yaesu's FBA-25 alkaline tray and Maha/Powerwerx NiMH AA cells (about 2500mAH) and appropriate charger.
--
Clint Bradford K6LCS
http//www.work-sat.com
Clint Bradford