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- BATTERIES
- Priority Customer Needs
- Increased battery capacity per charge cycle
- Existing battery capabilities are insufficient for some
users, particularly those who attach multiple accessories
or use their power chair/scooter as a one-passenger vehicle.
- Decreased battery size and weight - Users would
like to be able to collapse power chairs/scooters for travel,
but the battery box cannot be collapsed and weight is a barrier
for portability. Size & weight sometimes precludes the
prescription of a power chair because of access issues, or
because the user needs to load/unload and transport the chair.
- Alternative battery configurations – Current
battery configurations reduce the ability to design wheelchairs
that meet mass transportation requirements.
- Sharing power and control between the wheelchair
and accessories is not easily accomplished.
- Battery life is related to battery quality,
which in turn is related to cost. There is need for better
quality batteries at low cost.
- Reimbursement for new battery technologies -
Batteries with increased longevity will not be developed for
the w/c market unless third part reimbursement agencies are
willing to pay a premium for the increased capabilities.
- State of Existing Technologies
- Currently, power management and monitoring systems
must deliver excessive battery power to compensate for limitations
in motor technology and drive-trains.
- Advanced battery technology is appearing in
other industries. For example, lithium-polymer batteries yield
100 watts per kilogram (twice the power/weight ratio of lead
acid). They are also more robust - providing longer cycle
life. Computer, toy and power tool industries are driving
the development of these batteries, with carts and electric
vehicles being emerging markets. One problem to overcome for
lithium-polymer battery technology is a low surge current
tolerance relative to lead-acid batteries.
- Advanced battery technology is utilized in military
applications (e.g., Military special forces require small,
lightweight batteries with sufficient power to propel landing
craft through water and on to land), but this technology has
not yet been applied to w/c industry.
- Lead-acid batteries with higher energy densities
and longer cycle lives are available in other markets.
- Lithium batteries have better monitoring capabilities
(e.g., straight-forward correlation of battery voltage to
remaining charge).
- Lithium ion batteries have three-times the energy
density of lead-acid batteries.
- Integrated Controls - the CAN bus has been adapted
by TIDE programs in Europe (Multi-Master, Multi-Slave Control),
to provide integration of multiple devices all within the
same bus.
- Accessory outlets - Some DMEs install accessory
outlets as after-market items, however, many existing batteries
lack sufficient energy density to power the chair and an array
of accessory devices.
- Battery longevity - Some manufacturers reported
battery life extending beyond that reported in the white
paper (e.g., gel batteries should last 2 – 5 years). However,
service providers find that batteries are actually lasting
only 1 – 2 years. The difference may result from battery
degradation due to sub-optimal power management (recharge
practices) by users.
- Safety – batteries utilizing ether based
electrolyte are fairly benign and have shown resistance to
abuse.
- Ideal Technology
- Batteries should be lighter and smaller.
- Batteries should come in a variety of sizes,
shapes and weights. Such options would support the flexible
design of the power base. Designers must avoid batteries with
sizes, shapes or weights that cannot be readily procured in
the marketplace.
- Batteries with higher energy densities are needed
that can serve as a power source for additional electrical
devices. For example, it would be very helpful to power augmentative
and alternative communication and other essential/peripheral
devices through chair’s power system.
- Batteries are needed with higher charge capacity
that would allow the user to travel greater distances. This
is very important to consumers.
- Batteries should have a low leakage current
and be "user swappable" (the user can change the
battery themselves). User swappable batteries will require
some standardization (e.g. size, performance, connection,
safety, …).
- Modular power cells (analogous to power tool
power-packs), if small and light enough, would permit the
user to swap out batteries from a charging station on daily
basis – if user have sufficient dexterity and range of
motion.
- Battery should be compatible with airline stowage
requirements and the Air Carriers Act. Not all gel-cell batteries
are currently approved.
- Batteries with reduced size and weight are needed
that still retain their current power capacity. Such batteries
would reduce the charging capacity requirements for on-board
chargers.
- Batteries with smaller size and weight would
reduce the overall weight of the chair. This would help with
air travel and transportation needs generally.
- Smaller batteries would make power monitors
more accurate.
- Matching an intelligent battery monitor to the
battery technology would allow tracking of battery status
and extend battery life.
- Batteries require significantly improved cycle
life (increased number of charge and discharge cycles).
- Batteries need to be user safe for all normal
or likely uses (e.g. charging, discharging under load, leakage
discharge, …), environments (e.g. temperature extremes,
humidity extremes, …) and when damaged (punctures, over-charged…).
Other Suggestions
- Pair the specification and development of lithium
battery technology for wheeled mobility products with that of
electric bicycles and scooters. The electric bike and scooter
market is potentially huge. Successfully pairing would provide
the economies of scale needed to make advanced batteries affordable.
- The niche market issue has traditionally been
a barrier but now Lithium polymer battery manufacturers are
hungry for new application markets – including niche markets.
- Track advances in battery technology for electric
cars/bicycles. Leverage this industry’s advances and investments
in battery technology.
- A wheelchair consortium could provide lithium
battery developers with specifications for wheelchairs and
scooters. This would help to ensure that batteries developed
for electric cars/bicycles are suitable for wheeled mobility
products. Consortium could help shape guidelines for battery
specifications (standard size, capacity, …).
- Explore hybrid power systems. For example, augmenting
batteries with capacitors that store a reserve charge. Stored
charge provides additional power under heavy load conditions.
Another example would be an energy regeneration system analogous
to that used in automobiles.
- Explore alternative (to battery) power technologies.
For example fuel cells or solar power. Need economies of scale
in order to make alternative power technologies for wheelchairs
and scooters – (e.g., fuel cells, solar, …) affordable.
- Manufacturers should provide an outlets (connection
ports) on the chair (controller/bus) to plug in other devices
(analogous to a cigarette lighter socket in automobiles).
- Need to have a back-up power source for users,
as an option to acquire and add when power is lost unexpectedly.
- Push beyond existing solutions and incremental
improvements. For example, a power chair (or scooter) that
charges itself at night, in the consumer’s bedroom without the
user having to take any specific action. Power chair (or scooter)
should "always be charged," and alert the user to
problems that can be remedied by the user. Such a power chair
(or scooter) should also be available at an affordable cost.
- Barriers to Realizing the Ideal Technology
- At present, reimbursement policies are constraining
battery development, and are actually pushing the technology
backwards, due to reduction in reimbursement (e.g., installation
is often not covered by reimbursement).
- Wheelchair and scooter market is a niche market. "Last attempt" to
link wheelchair companies to advanced battery manufacturers
fell flat (e.g., advanced batteries had higher cost and were
not widely available).
- There is a need to develop a wheelchair industry
consortium, which can lay down the specifications and requirements
for the wheelchair battery. These can serve as guidelines
for advanced battery manufacturers to direct their research.
- The wheelchair industry has repeatedly invested
in advanced battery development with no concrete outcomes.
(This suggests that such a direct approach to is not likely
to be fruitful.)
- Need to convince third-party providers of the
long-term benefits of better batteries and chargers (e.g.,
increased battery life, decreased amortized costs), in exchange
for possibly increased purchase cost.
- Some (but not all) lithium battery technologies
have a potential for explosion. Battery technologies must
address regulatory issues of safety and environmental disposal.
- Priority Problems & Recommendations
Battery Problem 1: New batteries are being developed
without input from wheelchair stakeholders (industry, clinicians,
consumers, researchers, reimbursement sources) concerning today
and tomorrow's requirements for battery capacities, performance
and size/shape/weight dimensions. If the wheelchair stakeholders
communicate their needs to the advanced battery developers while
the battery parameters are being specified, the advanced batteries
can be designed more appropriately.Recommendation for Problem 1: Initiate a wheelchair
stakeholder consortium (W/C Consortium), preferably led by the
RERC on Wheeled Mobility. The W/C Consortium's purpose is to
develop a set of battery specifications that reflect current
and future power requirements. Once developed the W/C Consortium
should disseminate these specifications to emerging battery
technology developers and manufacturers, as well as to leading
industries with similar battery requirements (e.g., golf carts,
electric bicycles). The specifications should convey the short-term
needs for current wheelchairs, and the ideal requirements for
advanced battery technologies to power future mobility systems.
This information will permit battery developers to incorporate
wheelchair power requirements into their designs prior to full-scale
production.Battery Problem 2: Wheelchair users want to tap into
the wheelchair's power source to power electronic accessories
(e.g., augmentative communication devices, laptop computers,
cellular telephones). Tapping into the wheelchair's power source
is more convenient for the user than each device having its
own batteries. Currently, the wheelchair's power source is not
designed for this purpose. It lacks an appropriate interface
for conveniently connecting powered devices, and the power capacity
was not designed to supply accessory devices. DME dealers report
that adding an accessory adapter plug such as a twelve-volt
cigarette lighter is a common after-market practice. Many accessory
devices are already compatible with this plug. Accessory plugs
are becoming more a necessity than a convenience, as consumers
have increasing requirements to maintain electronic links for
information processing or telecommunications.Recommendation for Problem 2: The RERC on Wheeled Mobility
should work with consumers, clinicians and DME dealers, to define
the requirements for a universal accessory power interface.
They should then approach manufacturers to integrate this accessory
plug interface into the power system. The accessory plug(s)
should accommodate a wide range of electronic products. The
accessory plug should be within reach of the user, such as at
the controller box.Battery Problem 3: Users lack a full understanding of
the power monitoring and management practices needed to maximize
battery life. For example, experienced power wheelchair users
did not charge their battery on a daily basis, and did not appreciate
the importance of doing so. However, battery manufactures assume
these standard practices are followed when they establish the
battery's expected life. Some DME dealers report absorbing the
cost of battery replacements because the reimbursement systems
are unwilling to pay for more frequent battery replacements.
Consequently, many users do not realize the battery's full capabilities,
the manufacturer's product does not perform up to expectations,
and all stakeholders pay a premium for accelerated battery replacement.Recommendation for Problem 3: The RERC on Wheeled Mobility's
information dissemination program should develop a summary of
power monitoring and management requirements, written for consumers.
This summary should be disseminated to wheelchair users through
DME dealers, State Tech Act programs, Independent Living Centers,
UCP agencies and other appropriate sources. Where possible,
organize consumers and DME dealers to collaborate on demonstrating
the cost effectiveness of consumer education programs, by extending
battery life and thereby reducing replacement costs.Battery Problem 4: Battery power gradually diminishes
through use, until the user either recharges the battery or
drains the battery to the point where it can no longer power
the wheelchair. Existing battery power systems have no reserve
or auxiliary power source, which can provide supplemental power
for the wheelchair (and other powered devices), in emergency
situations. Consumers are not willing to reduce their existing
battery capacity, to create a power reserve. They want it to
add to their existing capacity.Recommendation for Problem 4: Emergency Auxiliary Power
System - The W/C Consortium should define the requirements for
a reserve power unit, for use in emergency situations. Requirements
for such a system include the following:
- Power capacity - approximately 10% of a typical
battery under high load conditions.
- Size - must be small enough to be integrated
within the wheelchair, specifically within the configuration
of the battery-box. This may be difficult because the battery
box is already full, but it is a critical issue, because
a new battery box mold would cost about $250,000 per manufacturer.
- Activation - should have a manual rather than
an automatic switch operation, so the user is aware of the
power situation and is prompted to take immediate remedial
action.
- Charging - auxiliary power unit must be recharged
with main power unit, to prevent charge degradation over
time. However, the auxiliary power unit should recharge
more rapidly than the main power unit (e.g., less than one
hour), so it can be readily available even after use.
- Cost - need to justify cost of auxiliary power
unit to third party payers, for manufactures to view this
as a business opportunity in the short-term. Private payment
from the aging baby boom cohort will eventually create a
market opportunity outside of the third-party system.
- BATTERY CHARGERS
- Priority Customer Needs
- Dealers should be careful to match the right
charger to the battery. Consumers want chargers, that perfectly
match with the battery technology so as to avoid any damage
to the charger or battery.
- Chargers should be easy to use, compact or light
weight.
- Two and four prong power plugs needs to be more
durable as they degrade quickly, particularly with regular
charging.
- Charger handles should be sturdy enough to handle
constant use.
- The location of the charging unit connector
should be accessible to users.
- Chargers should be very safe. Some consumers
have strong concerns about the possibility of severe shock.
- Chargers should meet the ANSI/RESNA standard
of 80% charge in 8 hours.
- State of Existing Technologies
- In older chargers, amp-meters (rather than volt-meters)
help the user determine the state of the batteries recharge
cycle. Cost considerations are reducing their use.
- Modern chargers provide a constant charging
current, so an amp-meter would not be a helpful.
- Electromagnetic Interference (EMI) may reduce
monitor accuracy, but appropriate shielding can eliminate
EMI.
- Medicare does provide reimbursement for on-board
chargers because it is not an up-charge.
- "Smart chargers" exist. They monitor
charge capacity over time so that the user can determine
when recharge capacity has diminished to 50% - 60% of original
capacity. Smart chargers would also permit the collection of
data concerning battery life across multiple users over time.
Some smart chargers can adjust to battery chemistry and shut
down when full charge is achieved.
- Data acquisition systems can collect data that
can be downloaded to a personal computer for analysis.
- "Pulse chargers" have been shown to
increase battery life from 100 cycles up to 2000 cycles –
but this depends on how "cycle" is defined. (In
federal lab work "depth of discharge" was defined
as being down 5-10% of capacity for some applications and
down 75-80% of capacity for vehicles).
- SBM (System Bus Management) provides an intelligent
read of battery status (for various battery types) in the
computer industry (a board level product costs in the $15
range).
- Battery cell robustness (e.g. number of charge-discharge
cycles, ability to tolerate rapid charging, ability to utilize "simple" charging protocols, …)
varies with the type of battery.
- The excessive size and weight of existing battery
chargers results from the use of transformer-based charging
technologies.
- Scooters have on-board chargers that can be
plugged straight into the wall, but wheelchairs don’t
have that capability.
- Existing on-board chargers have limited charging
capacity.
- Users with on-board chargers, typically do not
place heavy demands on their power supply. This is probably
the reason that charging capacity problems have not arisen.
- Chargers with sufficient charging capacity (for
power wheelchairs) are currently too heavy to include as an
on-board charger. Some chargers are larger/lighter while others
are smaller/heavier.
- There are serious safety and regulatory issues
with onboard chargers for wheelchairs. Wheelchairs lack a
common ground. In contrast, scooters are better grounded.
- Existing chargers do not provide users with
any information concerning the batteries current charge level;
recharge requirements; or the battery’s overall state
of operation. Without this information, users have to estimate
the power system’s needs through trial and error.
- Meeting Standards - dual-mode chargers (wet
cell and gel) are available but it took a long time to get
them developed and approved, so the market contains a large
number of chargers that are currently considered obsolete.
Many of these chargers don’t meet the ANSI/RESNA standard
of 80% charge in 8 hours.
- Electric vehicles (automobiles and buses) face
the problem of getting recharged on the road. A solution in
process is induction charging. There are safety issues for
this approach. An air gap of several inches means the power
field is strong enough to cross that space. This presents
a risk of either electromagnetic interference for pacemakers
and wheelchair controllers, or electromagnetic radiation for
the user and others. There is an access issue as well. The
wheelchair user will need sufficient space in order to access
the charging dock within the home or elsewhere, particularly
if shielding is required to address safety issues.
- Ideal Technology
- Charger should be smaller and lighter with sufficient
capacity for Group 24 batteries.
- Charger should be on-board or very portable,
depending on the user's needs. Whether the charger is on-board
or not, users want it to be light and accessible.
- It is critical that the process of charging
the battery should be simple and easy for users because charging
must be done on a daily basis.
- A charger that can accelerate the charging cycle
significantly beyond current ANSI/RESNA standard (e.g., 80%
in 8 hours). The benefit/cost must be assessed by individual
if accelerated charging cycle adds to cost.
- Chargers should utilize standard connectors,
which have adequate durability. (e.g. A barrel-type, three-prong
connector with a metal casing would have increased durability.
)
- The charger's power cord should be long enough
(and retractable) to accommodate the expected distance between
the chair and wall plugs -- such as those in hotel rooms behind
beds or desks.
- The charger’s connector should be within
easy reach of the user – which varies with the user’s
range of motion. Industry should be given a range of locations
that are highly accessible to the widest range of users, so
they can build these requirements into PM&M system design.
- Chargers that utilize auto-docking would have
significant value for people with severely limited range of
motion (high level injuries). Attendants are not always available
to assist these users with recharging.
- Chargers should be "intelligent." Intelligent chargers
should monitor battery status; work to maintain battery integrity;
adapt to different voltage levels; perform diagnostics; and
provide warning of battery degradation.
- Intelligent chargers should help the user to
monitor and manage their power system and extend battery life
to the optimum designed for by the manufacturer.
- An equipment provider should be able to download
battery usage information collected by a "smart" battery
monitor. This will assist preventive maintenance efforts.
- A "smart" charger installed onboard
the wheelchair/scooter, would continuously collect data on
usage. On-board charger can greatly simplify monitoring &
management process. For example, a "smart" charger
could monitor usage patterns, but the monitoring data would
be sporadic if the user was interchanging multiple chargers.
- The ideal charger would have a linear charging
curve, work under surge current conditions, and recharge the
battery rapidly under all load conditions.
- On-board chargers would be welcomed by industry
if they had sufficient charging capacity (echoed by industry
representatives). Industry would welcome any technology that
would make on-board chargers feasible because it would simplify
charger use by customers, and reduce costs (by reducing connections).
Other Suggestions
- Some chargers help preserve battery integrity
while others degrade it. In practice, there is no scheduled
maintenance program for power chairs, but if there was, it would
permit assessment of data collected in power system. Assessment
of battery integrity is possible with existing systems, but
would be better if the information could be downloaded from
a smart power management and monitoring system.
- The connector should be within easy reach of the
user – which varies with the user’s range of motion.
Industry needs to be given a range of locations that are highly
accessible to the widest range of users, as a guideline for
design.
- It is important to collect the history of battery
charge/discharge cycles. Continuity may be lost if user has
multiple chargers – the data collection unit may need to
reside with the battery or with the power monitor.
- Experimental charging systems should be evaluated
to determine their applicability to wheelchairs. For example,
pulse charging techniques might increase battery life by anywhere
from 100 to 2400 cycles. As a second example, inductive chargers
would eliminate the need to physically connect the battery to
the power source (being in close proximity to the charging unit
would be sufficient).
- Barriers to Realizing the Ideal Technology
- Need to explore safety issues for on-board chargers
and establish parameters for their safe use.
- The electromagnetic field generated by an inductive
charging system could raise safety/health issues for the user
and their equipment attached to the power wheelchair.
- Some consumers continue to use battery chargers
that were considered to be obsolete by the manufacturers.
- Priority Problems & Recommendations:
Battery Charger Problem 1: Existing chargers cause problems
in power management and monitoring and compromise battery performance
and integrity. Battery chargers do exist that have some of the
capabilities of the ideal charger listed below.Battery Charger Recommendation 1: Requirements for new
on-board or very portable chargers compatible with popular wheelchair
batteries:
- Charger should be designed to be sufficiently
small and lightweight to be incorporated on-board the chair,
or available as a very portable accessory – depending
on consumer’s preference.
- Charger should have sufficient intelligence
to monitor and manage battery status, provide optimal charge
to extend battery life to maximum possible. Should not work
on pre-determined program (e.g., trickle charge), but instead
sense the battery’s condition and current status in
the battery charge/discharge cycle.
- Charger should monitor the condition of the
battery – The most critical aspect of monitoring is
to know when it is time to get a new battery.
- Battery charger should monitor charging history
(upside and downside for consumers) – currently part
of SM Bus capability.
- Charge both sealed and open batteries.
- Smaller size (approximately 6"x4"x2")
- Reduced weight for on-board integration
- Sufficient charging capacity for Group 24
batteries.
- Standardized connectors.
- "Redundant display" would allow
the charge status to be displayed during a power outage.
- Charger lifecycle beyond 3 years.
- Efficient for fast charging (meet/exceed current
ANSI/RESNA standards (Part 14)– 80% of full charge
in 8 hours).
- Adjustable for operation on different voltages
(e.g., 115, 220, 230)
- Safety mechanisms to protect operator and
manufacturer (e.g., GFI, rain test), to permit individual
to remain in chair while recharging.
- Address ergonomic issues for user interface
(e.g., formable plugs, retractable cord, easy access to
the plug/connector by user, …).
- Silent operation (particularly for overnight
charging in same room with consumer).
- Meet all applicable standards and regulations
(e.g., ANSI/RESNA, VA, UL) for all parameters covered (e.g.,
storage and operating temperature range, vibration, drop)
- Retrofitting should be option for existing
chairs.
- Business Issues:
- Cost to manufacture/wholesale/retail levels
- (Currently $50 - $70 retail price depending on charger
capacity).
- Medical necessity – justification
may be required for reimbursement, particularly for
retrofitting existing chairs.
- Government R&D Issue - hit budget cycles
or experience year delay.
- Advanced battery technologies may permit development
of alternative chargers (e.g., inductive, SM/Communication
Bus) to match new batteries.
- POWER MONITORS
- Priority Customer Needs
- More accurate power monitors are needed. Volt-meter
based monitors are simply not accurate, particularly for
lead-acid batteries under varying load conditions. Users have
to develop a "ballpark" understanding of the battery’s
remaining capacity through trial and error. Consumers learn
to work with this process but it is not optimal.
- Monitors are needed which can provide user with
sufficient detail about battery status, condition, remaining
travel distance etc. Existing monitors have insufficient indicator
detail (e.g., single green/red light that flashes when you
are nearly out of power, while digital monitors have a row
of bars which are more useful but still lack sufficient accuracy
for distance or time remaining on charge. They require the
user to estimate "remaining time" through trial
and error (user is forced to become the battery monitor!).
- Improved monitors are especially important for
users placing heavy demands on their power systems.
- State of Existing Technologies
- Monitors are not part of a "systems" solution, where
the system includes the monitor, charger and battery.
- Monitors are not matched or attuned to the performance
characteristics of lead-acid battery technology.
- Power indicators do not accurately measure power
remaining.
- Power indicators do not accurately show the
power remaining.
- Advanced monitors of power status and battery
condition, might be available in the federal labs.
- Appropriate technology exists in other industries
(e.g., SM Bus), but the challenge is applying them to lead-acid
cells.
- The CAN Bus could provide multiple functions
for wheelchair management and other functions (e.g., heads-up
display, AAC interface).
- Ideal Technology
- Monitor should provide "range" information
to the user. Range (e.g. remaining travel distance), as estimated
from residual battery charge, will be highly dependent upon
user behavior, electronic accessories and travel (load) conditions.
- Monitor should provide user-specific information
about status of charge, distance remaining, and indicator
of requirement for charge.
- Monitor should support a range of display interfaces.
- Monitor should be an integral part of a "power
management and monitoring system." Battery range and
condition could be determined from information stored in/available
from this system.
- Monitor should estimate the time/distance remaining
on the battery's useful charge. (This can probably be accomplished
by analyzing the recent (e.g., past three hours) usage pattern.)
- A scheduled maintenance program would permit
DME’s to extract critical data on power management and
monitoring (e.g., load testing, battery condition).
Other Suggestions
- Some chargers help preserve battery integrity
while others degrade it. In practice, there is no scheduled
maintenance program for power chairs, but if there was, it would
permit assessment of data collected in power system. Assessment
of battery integrity is possible with existing systems, but
would be better if the information could be downloaded from
a smart power management and monitoring system.
- The connector should be within easy reach of the
user – which varies with the user’s range of motion.
Industry needs to be given a range of locations that are highly
accessible to the widest range of users, as a guideline for
design.
- It is important to collect the history of battery
charge/discharge cycles. Continuity may be lost if user has
multiple chargers – the data collection unit may need to
reside with the battery or with the power monitor.
- Experimental charging systems should be evaluated
to determine their applicability to wheelchairs. For example,
pulse charging techniques might increase battery life by anywhere
from 100 to 2400 cycles. As a second example, inductive chargers
would eliminate the need to physically connect the battery to
the power source (being in close proximity to the charging unit
would be sufficient).
- Barriers to Realizing the Ideal Technology
- Consumer acceptance of more complex monitors
will depend on the reliability and accuracy of the new monitors.
- Any range indicator will be highly dependent
on user behavior, number of accessories and travel (load)
conditions.
- Financial considerations have limited the charger
options developed by manufacturers. These manufacturers are
aware of more reliable monitors in parallel industries that
could be modified to meet the needs of the wheelchair industry.
However, if these monitors increase the chair's cost, they
won't be covered by third party reimbursement.
- Priority Problems & Recommendations:
Power MonitorProblem 1: Current monitoring systems do
not fully support all the needs of different users for information
to conduct appropriate power management and monitoring. Some
consumers rated improved monitors as high priority and other
rated it lower.Power Monitor Recommendation 1: Develop improved monitoring
process/output that provides required discharge/recharge information
to user (daily) and service provider (history). An accurate
indicator of Power Monitoring and Management parameters would
include the following:
- Accurate residual energy monitor (specifically
a "gas gauge") – capable of translating
energy into time (hours/minutes) and distance (miles/feet)
parameters.
- Provide numeric readout instead of single
light or LED bars, or other user-friendly readouts.
- Monitor battery status in terms of cycle life.
Monitor condition of battery rather than capacity (could
be built into intelligent charger) -- Most critical aspect
of monitoring is to monitor condition of battery – e.g.,
know when it is time to get a new battery.
- Monitor related power system issues – including power-train
and accessory power.
- Record accumulated "watt hours" to establish battery
performance.
- Power monitor should be readily accessible
but non-obtrusive.
- Power monitor needs to accommodate monitoring
of power requirements of accessory devices such as augmentative
communication, cellular telephones, etc.
- Best solution should be "systems"
approach so that monitor is part of total power/drive-train
"system" – this will optimize power system
(battery) performance as defined by manufacturer’s
specifications.
- Monitor should be "integrated into the
wheelchair" to ensure it collects and tracks information
related to chair use over time.
Power Management and Monitoring System
- Power monitoring and management should be approached
as a system, resulting in a system's level solution. Battery,
charger and monitor should all be integrated into power management
system. This would avoid compatibility issues for components.
- Most of the users felt there was a need to integrate
the power wheelchair with computers, cell phones and other electronic
accessories and to develop a standard communication protocols
and interfaces.
- Retrofitting of various components and devices
from parallel industries that can be modified for the wheelchair
industry represent significant business opportunities.
- For all technologies, commercial viability is
heavily dependent upon third-party reimbursement. Challenge
manufacturers to collect data to make evidence-based arguments
to justify higher reimbursement by third-party systems. Analogous
to Cooper’s demonstration of life cycle of lightweight
wheelchairs. Must be done within parameters of reimbursement
system, to provide current practice data for cost-effectiveness
studies.
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