I get emails daily and there's much talk on my Message Board about lithium battery power. On the face of it its easy. Just cough up some money and replace those awful heavy lead batteries. But there are a few things to be aware of.

1. There are many types - but three main types of lithium battery. And they all have different voltage and other issues when it comes to powerchairs. Our powerchair batteries are generally 24v (Nominal) and comprise of two lead acid, Gel or AGM batteries.

We need to match this voltage as closely as possible because Power Wheelchair controllers are very "safe" and will spot that something is different! They will then either refuse to work, or give annoying error messages (like over voltage) etc.  There's a chart below showing the exact voltages of each type of battery and you will be able to calculate the best match. The trouble is that every powerchair controller will respond differently here. You may have to take a gamble!

2. These "types" of lithium battery are all different electrically. Apart from voltages, some are very high resistance and so are useless with high currents we need. Some are excellent! Some are much more energy dense than others, and some are little better than the lead batteries we are trying to replace.

3. Some are "safe" in that on puncturing the case, or on overcharging they will not burn. Others explode or burn violently like a firework... Not good if they are under you in a powerchair.

4. Some are only available in small capacity cells, and so need making up into bigger packs. Some are available as large 50, 60, 80, 100 or bigger Ah cells.

5. Some can be charged fast.

6. ALL need either a battery management system, or a charger like the excellent Hyperion EOS1420i-NET3 charger that can balance cells as it charges.

7. Some are easily available, and some are only accessible in large quantities, and supply is sporadic. At least as of 2011 as I write this.