Batteries are the HEART of any electric vehicle. They are the single most important factor by miles in the design and performance of a powerchair or scooter.

So why are the Power Wheelchair and scooter manufacturers not all embracing this huge leap in technology?  (I would just love to know!) ...

The advantages are many. Here are just a few:

• At least double the range is easily possible. Often MUCH more!  This means lots to some users.
   
• At least double (or triple) the speed with greater levels of torque is possible. See my new powerchair
   
• Much lower weight, and battery size is possible in a smaller narrower powerchair. Typically much less than 1/4 the weight for the same "sized" battery in Amp hours. And half the physical size.
   
• MUCH faster charging - typically 1 hour for a full charge.
   
• Much longer, greater lifespan, like 2000 to 3000 cycles compared to 350 to 500 for good Gel batteries used now!  New batteries every 10/12 years instead of every 2 to 3 is easily possible.

This technology is no longer new. People and companies are using Lithium Ion Phosphate batteries like the A123, CALB, Headway, and many others to build everything from electric cars to bicycles.  All of this lithium batteries are made in China. I will show the best/most popular for electric vehicles use below.

Are their any disadvantages? Yes. Cost. And convenience....

Right now it will cost about 3x as much as your existing lead/Gel batteries. But given that they will give better range, better performance, lower weight, faster charging, and last much longer then its really actually cheaper! Its just painful to begin with!
 

Well the answer is yes. And no. You "can" if you understand what you are doing but its not quite so simple as that.   I can because I understand what I am doing.  To begin with you need to understand the different "common" types of lithium batteries, their cell voltages and the dangers of some types.

a) LiPo batteries  While its relatively easy and cheap to get hold of very powerful Lithium Polymer (LiPo type) lithium batteries as used in model aircraft, and model helicopters these are sadly unsuitable for our usage for several reasons. 

To begin with they are easily punctured, which causes them to smoke and burn... As does charging any one of the 7 individual cells above 4.200v.

These LiPo batteries are cheap, this is a 10Ah one. It is "35C" meaning it can have 35 times its capacity drawn from it in Amps. So it can produce 350 Amps if a thicker cable was used!  It can start your car. And its barely bigger than a coke cola can. To replace a pair of 50Ah lead acid batteries in your powerchair would require 10 of these connected in parallel to provide the same range. But that would take up 1/3rd of the space! And be 6 times lighter.  So you really need to add 3x more capacity. So as to get an advantage over your old lead batteries. So instead of replacing Ah with Ah you could increase it by 3x because in the same space 150Ah will fit. And still be much lighter.

Each one has of these has 7 cells (to give the closest match to a pair of 12v powerchair batteries) and a 4.200v charged voltage per cell. So it will be at 29.4v fully charged. When charging you MUST use a special charger like this one here to ensure that all cells are charged to the exact same voltage or a fire can easily result!
 

b) Lithium Ion - as used in cameras and laptops.  Much of what is written above is also true of these lithium Ion batteries. So they also are pretty unsuitable for power wheelchair or scooter use. They are also only usually available in smaller capacity cells so building packs is too expensive and heavier than the above. These are 4.1v charged or 4.100v charged. (usually)  And they have a metal shell, so are heavier, although stronger. Punctured cases as can happen with the LiPo batteries above is more difficult.

c) Lithium Iron Phosphate OR LiFePO4 cells. These are sold as A123, Headway, CALB etc. These are the ones we need for powerchair use. They are available in both round tubular cells, like huge AA batteries. or in big "prismatic" cells. Such as the CALB cells are available in BIG Ah sizes. The cylindrical calls are available in smaller sizes. They are easily made into packs that are the correct size for a powerchair. Using nothing more than a spanner! These cells are SAFE. There is probably less danger than the ones in your powerchair now.

But unlike the two lithium's above their energy density of LiFe cells isn't quite as brilliant. It is about twice as good size for size, weight for weight compared to your Gel batteries though!

So these are what I am using in my latest powerchair currently under construction. new powerchair 

This will allow both 12.7 MPH and  50+Km range easily at the same time while saving 60lb of weight!  And allows for sensible off road capability and fat high floatation tyres for ride and soft surfaces like sand.

The one opposite is 10Ah. 12Ah, and 16Ah Headway cells are also available. These are charged at 3.600v and 8 are needed in series to give 28.8v which is the nearest you can get to a pair of 12v power wheelchair batteries.

And then use these sets of 8 in multiples (in parallel) to give you your desired capacity in Ah.

Typically you will be able to get 100Ah in the space where your 50Ah batteries were removed.

These need to be balanced when charged up. And again I will use the excellent and cheap Hyperion charger here