Wheelchair batteries are different from car batteries because they are used in a different way. A car battery's main function is to start the engine. At other times, it is loafing along, constantly being charged by the alternator. A wheelchair battery is usually charged once a day and must supply large amounts of electricity while it is running. So wheelchair batteries must be a special type called deep-cycle. This means that the battery can be almost completely discharged without damage to the battery. If a car battery is used for a wheelchair, it will soon fail.
Wheelchair batteries will last longer if they are kept as close to full charge as practical. They are unlike the small nickel- cadmium batteries that need to be run down occasionally to preserve their full capacity. Most users need to charge the batteries every night to keep a full charge. Modern battery chargers are automatic so there is no problem of overcharging. If a wheelchair is used only occasionally, the battery needs to be charged at least once a month, and should be charged whenever it is used during a day. The life of wheelchair batteries depends on how heavily they are used. Most last about a year. Compare this with the life of most car batteries, which last about 4-5 years. The difference is due to the deep cycling of the wheelchair batteries. Some users who travel mostly indoors can use a battery for 2 years. Anything beyond 2 years of life is rare. The best way to tell whether a battery is getting old is to notice if the wheelchair is getting weak at end of trips that were no problem when the battery was new. New batteries require about 5 cycles of use and recharging before they reach their full capacity. So don't push a new battery for a few days. Freiler Wheelchair has a special computer battery tester that cycles new batteries for several hours to check them and ensure close to full capacity of the battery when installed. The same tester is used to test the old batteries to make sure that they were really bad. There are two types of batteries for wheelchairs: wet and gel. Wet batteries require adding distilled water about every two months. Wet batteries can be damaged permanently if the water level falls below the level of the battery plates. Adding water is often quite difficult, even for someone with training and no disability. The batteries are heavy and difficult to reach. So adding water is usually impossible for wheelchair users. We will be glad to do it for our clients, even though MediCare will not pay for this service. If you do it yourself, follow these precautions: 1. Use only distilled water. Tap water has minerals that will damage the battery. 2. Don't overfill the battery. If the outside of the battery is wet, the battery has been overfilled. Fill only to about 1/8" below the ring in the hole. Use a flashlight to see the level clearly. Overfilling the battery will result in leakage of battery acid, which will quickly ruin battery connections. The water level will rise as the battery is charged, so a weak battery with low water level should be filled less than normal. 3. Be careful not to short-circuit the battery terminal with any metal. The sparks can ignite the gas in the battery and cause an explosion. Don't smoke. Be careful not to get battery acid on skin and in your eyes -- use gloves and eye protection. 4. Wipe up any spills and replace the caps tightly. Gel batteries avoid many of the problems of wet batteries. They never need water. They eliminate corrosion problems. They are much easier to take on an airplane trip because airlines require wet batteries to be removed from the wheelchair and placed in a sealed container. The main disadvantage of gel batteries is that they have about 10 to 20% less capacity than comparable wet batteries. This is usually important only for users who travel long distances. They cost more and MediCare will not reimburse us for the full price, but this is not the user's problem. If you want to switch battery types, make sure that the battery charger is suitable for the type of battery. Many old chargers will not charge a gel battery properly. Most new chargers have a switch to select either type of battery. Many chargers will not charge a completely dead battery. Some have a button that will allow manually starting the charge cycle. In other cases, a different charger must be used. Charging a battery that has been dead for several months is very difficult and requires several days of charging. The battery may be permanently damaged. So it is best to keep batteries charged, even if they are not being used. Whenever you plug in the charger, always check that the battery is charging, as indicated by a meter or light. The charger plug is subject to a lot of stress, so be sure that the cord and plug are in good condition. Selecting the Best Tires There is no perfect tire for every purpose and every person. A user must decide what is important and select the tire that has the least undesirable qualities. The factors to consider are: 1. Weight 2. Puncture-resistance 3. Durability 4. Comfort of ride 5. Traction The first decision is air or no air. Air tires are light, have excellent ride and traction, and good durability. But many users will sacrifice all these to avoid the bugaboo of flat tires. So they resort to using airless tires. Airless tires come in several forms: solid, inserts, and foam-filled. Inserts are foam rubber tubes that are inserted into pneumatic tires to make them airless. Some tires are too bulky for inserts, and these are filled with foam. Using airless tires on a power wheelchair makes sense for most users, because the extra weight is not a problem. Airless tires are stiffer that pneumatics so the ride is more uncomfortable with airless tires, especially for smaller sizes. Many new power wheelchairs have springs on the rear wheels, so ride is acceptable with airless tires. A reasonable compromise is to use airless tires on the rear of a power chair and pneumatic tires on the front. The pneumatic front tires make it much more comfortable when traveling over rough streets and sidewalks. If needed, one can usually limp along on a flat front wheel by leaning. Another way to get smoother ride is to use suspension forks in front. These are available for some power wheelchairs and a new lightweight version is available for manual wheelchairs. There have been attempts to solve the problem of flat tires, but none have been very successful. One is to use a thorn- resistant tube. These have thicker rubber on the outside, and will resist small punctures. These should be used for power wheelchairs when available. They are much heavier than regular tubes so they may not be suitable for manual wheelchair users. Another attempted solution is to insert a tough plastic strip between the tube and tire to block punctures. The problem with this is that the strip tends to shift and the hard edge can cut into the tire and cause flats. Another solution is to put a sealer inside the tube to seal punctures. The main problem with this is that the sealer tends to clog the valve and cause leakage. If sealer is used, one must be very careful to check for valve leakage whenever air is added. Sealers only work for small punctures. Another way to use sealer is to carry a can of pressurized tire sealer to use in case of flats. This usually works for small leaks. Make sure that the damaged tube is replaced as soon as possible because this is only a temporary fix. The gray rubber used for most wheelchair tires wears rapidly. Users who travel a lot on streets might be able to use black rubber tires, which last much longer because the carbon added to the tire makes it much tougher. Unfortunately, black tires are available only in a few sizes, probably because the tire manufacturers sell more tires if they wear out quickly. Black tires may produce slight marks on white floors. Care of Tires 1. Keep tires inflated at the proper pressure. The pressure is always stamped on the tire. Use a hand pump or a small electric pump with a gauge. Do not use a gas station air hose. Wheelchair tires have very small volume and it is very easy to explode a tire. Keeping the tires inflated will increase tire life, decrease rolling resistance, and keep the wheel locks effective. 2. Replace worn tires promptly. Don't wait until the black cords of the tire show. Tires are much less prone to flats if they have adequate tread. Wheel locks will work better with good tires. 3. Check your tires regularly. Sometimes a puncture will cause a slow leak that is not obvious. If you do find a small nail in the tire, leave it in place to seal the leak and get the flat fixed. The Importance of Proper Seating Proper wheelchair seating is more than just comfort. Lack of proper seating can lead to poor posture and pressure sores (decubitus ulcers). Selecting the best seat depends on the needs of the user. The best for an active para will probably not suit a quad. The factors to consider are support, pressure relief, weight, and maintenance. Support in a cushion provides a stable base, which is essential for proper posture. This has to be balanced with pressure relief, which ensures that no part of the body receives excessive pressure. If pressure at a point is high enough to cut off blood flow, the tissue will deteriorate and an ulcer will form. Decubitus ulcers are extremely serious and very difficult to heal, often requiring months of hospitalization. So ulcers need to be prevented, and proper seating is the first defense. Another way to prevent ulcers is periodic relief of pressure by shifting the body. If the user can shift in the seat independently, this should be done frequently. If this is not possible the user needs to be provided with the best seat possible and may need other means of pressure relief such as transfers out of the chair or a power tilt or recline seat. Users need to have their skin checked regularly to spot ulcers. Any signs of problems, such as red skin or abraded skin should lead to corrections, such as more frequent pressure relief or better seating. The traditional sling seat and back has numerous problems. The sag of the seat tends to rotate the hips inward, and the top of the pelvis tends to slump backwards. There is nothing to prevent sliding forward in the seat, so the user is slumped in the seat with back curved, head leaning forward, and neck bent upward. This seating is not suitable for long-term use. Its only advantages are low cost and the ability to fold easily. Foam seat cushions have improved lately so that they can provide adequate seating for users with moderate needs. The foam can be contoured to provide a stable posture base. The density of the foam can designed to provide moderate pressure relief. The use of multiple densities of foam can provide both pressure relief and stability. Light weight, moderate cost, and easy maintenance are advantages of foam. Air cushions can provide excellent pressure relief and are usually prescribed for users who are prone to ulcers. The disadvantages of air cushions are poor support and maintenance problems. The cushions tend to be squishy, especially the thick ones. They can get punctures, and the inflation must be maintained to ensure that they don't bottom out. Gel cushions can provide more stable support than air cushions and still provide good pressure relief. Disadvantage are that they are heavy and can leak. The gel needs to be mixed periodically to keep hard spots from forming. Gel cushions need to be fitted carefully to ensure that all areas have an adequate thickness of gel. A new type of cushion uses honeycomb cells of plastic to form a seat that provides good support and pressure relief. It is also light, provides good ventilation of the skin, and is machine washable. A proper seat cushion requires a proper seat platform. Using a good cushion on a sagging sling seat defeats its purpose. If a flat seat surface is not available, a rigid cushion insert can be used to avoid a sag. A proper back is part of a good seating system. A rigid back with contoured cushion is best. If this is not possible, at least some support can be added to the lumbar or sacral areas to allow a more upright posture. Wheelchair Safety 1. Keep wheelchair in good condition; don't wait until it falls apart. See section on maintenance . 2. On power wheelchairs, always turn power off before transferring, when using a wheelchair lift, or when on a cliff. One user bumped into the joystick while on a van lift and fell backwards off the lift. Fortunately, he survived to learn the lesson. It's a good practice to turn off power whenever you are not driving the wheelchair. This saves a bit on battery juice and decreases the danger of you or someone else accidentally bumping the joystick. On manual wheelchairs, always set wheel locks before transferring. 3. Don't pull backward on doors or other objects when sitting in a manual wheelchair. A door may suddenly release and you may tip over backwards. 4. Don't put heavy loads on the back of a manual wheelchair. It may make the wheelchair tip over backwards. 5. Don't remove the anti-tip wheels on a power wheelchair. If you encounter an obstacle, the torque of the motor may tip you backwards. 6. Don't let children play with your wheelchair. They should be instructed to never touch your wheelchair controls. Don't let them ride on battery cases or on the footrests; these will break if they do. 7. Use a flag if you ride the streets. Use headlights and flashing taillights if you ride the streets at night. Pick bright colors for wheelchairs. 8. Don't go up or down steep slopes. You may lose control and tip over. 9. Have the programming of your power wheelchair set so that it does not go faster than you can handle, especially in reverse. 10. Beware of caster flutter, which is the rapid side to side motion of the caster. This usually happens at high speed, such as when going downhill. It can throw you forward out of the chair. If your casters flutter, get them fixed. 11. Avoid riding in the rain. Wheelchairs are generally not waterproof, especially the electronics. If the electronics gets wet, the wheelchair may behave erratically. Wheels lose traction when wet, especially with urethane tires. 12. Beware of the effects of radio/TV stations and cell phones on power wheelchairs, especially older models. Turn wheelchair power off before using a cell phone. If anything weird happens while driving, turn off the power immediately. 13. Read the operating manual for your wheelchair and observe all the precautions. A useful general policy for safety is to prevent accidents before they can happen. Instead of just being more careful, think of ways to prevent problems even if you happen to make a mistake. Instead of being careful not to bump the joystick, turn the power off. Don't use high-speed mode indoors, where a mistake might send you into a wall at full speed. Plan ahead of time for emergencies, such as brake failure on a power chair, a power chair moving by itself, or a manual chair tipping backwards.
