My Segway LiFeMgPO4 (mfg by Valence) batteries are five years old with 7700 miles. They provide about 90% of the range they did when new. Your "year or 2" is

My Segway LiFeMgPO4 (mfg by Valence) batteries are five years old with 7700 miles. They provide about 90% of the range they did when new. Your "year or 2" is well taken, but suggests cheaper (e.g. some Chinese knock-offs) cells or systems that aren't very smart about preserving battery efficacy. Long life is possible with appropriate care.