This is one battery manufacturer of many. The future is already here and powerchair manufacturers are not using it.

Much like 25 years of Ni-Cad battery technology, or Nickel Metal Hydride. They just keep doing whet they did every year.

Powerchairs still use mostly brushed motors when brushless technology with much  improved efficiency has been around for 20 years for e.g.  No pressure to move on.. They have things too easy.

These batteries above are Lithium Ion Phosphate batteries.  They cure that power/weight problem and have been available for a year or two now.

The Group 24 sized ones for e.g. as used in most full sized powerchairs, are only half the weight, offer double the range, have a much lower self discharge rate, and can be discharged thousands of times down to 100 percent rated capacity. Compared to the traditional lead based batteries that the powerchair manufacturers fit as standard. They are not cheap. But last much longer so mostly offsetting the additional cost.

So apart from doubling your range and making faster higher performance powerchairs and scooters they could also last about 4 times longer in service.

And they can be charged using your existing stock wheelchair multi stage charger amazingly! They can also be fast charged if you prefer at very fast rates. 

Unlike the Lithium Polymer batteries that I use in my T-Rex 500 Radio Controlled helicopter, or the lithium Ion batteries in my laptop these new batteries are intrinsically safe to use. That's pretty important in a wheelchair where you are sat on top of them!

My "hobby" helicopter Lithium Polymer batteries can burn or explode if overcharged. Quite violently. Bad idea in a powerchair!

These new Lithium Phosphate ones cannot. What's more the voltages are extremely similar to our trusty old lead based batteries. So you can use them directly.