Lithium batteries are a relatively recent development in mobility scooters, and may eventually replace lead acid batteries as the de-facto standard. So how do you choose? Below are the some of the main considerations you should think about.
The energy density of lithium batteries is many times higher than that of lead acid batteries. That means for the same weight, lithium batteries can store many times more charge than lead acid batteries.
Therefore, mobility scooters can be made lighter so that they can become more portable. The lightest portable scooters that use lead acid batteries typically weight about 45 - 50 kg, while those using lithium batteries weigh half as much.
Lithium batteries are more costly than lead acid batteries. That means if you buy a lithium battery-powered scooter, it will not only cost more, but will also cost more to maintain in the long run because you'll need to replace the batteries every 1 - 2 years.
90% of lead acid batteries used in mobility scooters come in 3 sizes: 12AH, 20AH and U1. They are all 12 volts, and are connected in series to power a 24V motor. Not only are they used in mobility scooters, they are also widely used for electric bicycles, electric scooters and back-up power systems.
This kind of standardization is like the AA, AAA or C batteries that we are all familiar with in our household devices such as torch lights and remote controls.
This means that you are not restricted to go back to your original supplier to buy the batteries. This gives you the freedom to choose your own batteries (some brands, such as LONG batteries, are more reliable than others). It also means that if you are bringing your scooter to a far-flung town, there's a good chance of you can find compatible batteries locally instead of shipping it from a far-away country or city.
Lithium batteries, on the other hand, are custom-made to fit the particular model of scooter you have bought, and you have to go back to the original factory or shop to buy the batteries.
Lithium batteries have been known to catch fire due to thermal runaway, which does cause a risk to life and property. Lead acid batteries have no such problem; they do bloat due to age or overcharging, but they don't catch fire.
So if you are buying a lithium battery powered mobility scooter, it is best to choose reputable brands such as Solax.