Been using the lifepo4 batteries from Bioenno Power for about 18 months. Very flat discharge curve. Works great, no complaints.

Just bought the 9Ah battery and charger was $111.99 ($10 shipping) in the same size format as the "standard" #1290 SLA batteries we all seem to use (used?).

http://www.bioennopower.com/collecti...ifepo4-battery