Hands down the best off the shelf lithium batteries for wheelchairs is the Abyss 120AH 12V Group 24 Battery. I had a pair in my Invacare SP2 and Permobil F5 chairs. Top quality cells and German engineered BMS. Tripled my range. About $2,500 for a pair. Great tech support and US made in Florida. Has Bluetooth and works with iPhone. DO NOT buy Dakota Lithium batteries! Crap batteries. Horrible customer service. Tons of complaints on BBB website.
I live on steep hills. Because of the internal resistance on typical AGM or Gel batteries ALL my chairs in the 33 years I’ve been using them when going up steep long hills the battery cables, connectors and electronics get real hot and the chairs overheat, slowdown and turn off. Burned out tons off cables, connectors and power modules because of the internal resistance in AGM and GEL batteries. With lithium ever changed! No more overheating, fried connectors, power modules or the chairs slowing down under heavy loads. Lithium batteries (the right ones!) ARE LIFE CHANGERS! Period! Worth the money SOOO Much!
Working with a manufacture right now to build a universal 24V 200AH LifePO4 drop in replacement for wheelchairs. Should be available by March..