Power Wheelchair Batteries

Most power wheelchair batteries are "deep cycle" lead acid batteries. Deep cycle refers to the fact that wheelchair batteries are designed to be discharged deeply, which means that each discharge cycle uses the majority of the battery's available capacity. (This differs from automobile batteries which are "starter" batteries, designed to provide large bursts of energy over a short period of time, and are not meant to be discharged fully.) Because of this deep cycle nature, wheelchair batteries typically need to be re-charged frequently, and many users will recharge the battery every day.

There are 3 main characteristics of deep-cycle, lead-acid batteries: capacity, current rating, and type of cell.

Capacity is expressed in ampere-hours (Ah) and determines how long a battery can function. The capacity of a typical deep-cycle lead-acid battery ranges from 30 to 90 ampere-hours corresponding to 3 to 9 hours of continuous use of an electric wheelchair that runs on 10 amperes. Few people use their wheelchair continuously.

Current is expressed in amperes (A) and refers to the rate of electron flow.The larger the current rating, the greater the ability of the power chair to travel over rough terrain and obstacles.

Type of cell refers to whether the battery is a wet-cell lead-acid battery or a gel-cell lead-acid battery, which are the main types of power wheelchair batteries available. While both may be used in a power wheelchair, manufacturers usually recommend gel-cell batteries because of maintenance and environmental concerns with wet-cell batteries.

Wet-cell batteries usually have a larger capacity than gel-cell, can provide more power, and usually cost less. For these reasons, they are still the battery of choice for many users. Wet-cell batteries are available in vented and sealed versions:

* Vented wet-cell batteries must be regularly maintained by adding water to the battery on a regular basis, since the water tends to evaporate over time. This can be challenging, as the person doing the maintenance is exposed to acidic materials every time the battery case is opened to add the water: chemical burns can easily occur, and chemical spills can also corrode the wheelchair.

* Sealed wet-cell batteries are a closed system, so one does not have to maintain the water level. Still, the potential exists for a chemical spill, due to boiling, or a damaged battery case.

Because both of types of wet-cell batteries have chemicals, neither is allowed on airplanes.

Gel-cell lead-acid batteries were developed to be maintenance free with no chance of chemical spills, and so are able to be easily transported on airplanes. The main disadvantage of gel-cell batteries is that they typically have about 10-20% less capacity than wet batteries, and are more expensive. Still, unless the user regularly travels long distances, they are likely to be the first choice for most power wheelchair users.

When purchasing a new wheelchair battery, make certain that you have the correct charger for the type of power wheelchair batteries you will be using. Using the wrong battery charger can cause permanent damage to the battery. Since a wheelchair battery is a "deep cycle" battery, it is meant to drain nearly completely, and then be recharged. Most batteries can be recharged up to 300 times before losing the capacity to hold power.