Ops Management

The Value of Power Backup Systems for Lift Products

Power backup systems or uninterruptable power supplies (UPS) for stairlifts, vertical platform lifts or other accessibility products have become a staple option to offer clients… and they have even been integrated as the base offering by some vendors.

The reality is that a typical commercial UPS is not designed to handle motor loads, and therefore manufacturers of mobility equipment have had to design custom backup systems or DC-powered units to meet the reliability requirements of the market.

The reliability benefits provided by a backup power system for these mobility aids are readily understood by those in areas where the consumer power grids are known to have brownouts or even rolling blackouts during peak power consumption.

For the equipment provider, the benefits of these systems also revolve around increased revenue and potentially a reduction in service calls — since service calls are typically related to poor electrical installations in a client’s home or utilizing a common circuit to operate other appliances at the same time, which then trips a breaker.

Doug Roberts of Roberts Lifts Inc., Delta, British Columbia, knows the benefits of offering power backup systems to customers, but also knows such work must be done correctly.

“We have been installing lifts for 10 years,” Roberts says. “We have seen numerous methods to provide backup power, and in many cases, they can improve reliability for the consumer. But the type of system and its configuration are very important. If poorly selected, it can actually increase costs and create very unhappy customers.”

Power Backup Considerations

There are several ways that a UPS or power backup system can be effectively configured for accessibility devices.

The motivation for a provider and his or her front-line staff to provide power backup is based mostly on two things: customer satisfaction and reducing the number of warranty and service calls. Therefore, the increased revenue from these options truly does create a positive business effect rather than increased customer complaints.

Topics to consider when evaluating a backup system can include:

  • How many devices the client is trying to back up.
  • The number of usage cycles a client will realistically need to operate the device during a power outage.
  • Power draw requirements of the device.
  • Total lifetime reliability.
  • Impact on performance of the accessibility device.
  • Commercial availability.
  • Total cost of ownership.

There are four main power system architectures in today’s market place: Offline or standby; online or active; online with switching; and double conversion.

Depending on the number of devices that a consumer is trying to support, any of these could be incorporated into either
a point-of-use (one system for each accessibility device) or centralized (one central power backup system for many devices) configuration.

Most of the time, providers are dealing with single devices and dedicated power backup systems — and the majority of systems are the offline, online, or online with switching type. Double conversion systems are typically used for larger commercial or industrial applications, where the total power need is quite high.

Sample diagrams 1, 2 and 3 show how these main options work.

Lift Battery Power Backup

A comparison of the different systems’ pros and cons is in figure 4. Fundamentally, the online with switching approach is preferred from a performance and reliability perspective, while from a cost perspective, the offline or online options can be desirable. This largely derives from the philosophy that batteries that are left for long periods of time in an offline system may not be “good” when it really counts, and that when a battery does malfunction in an online system, there is no main home grid access to allow continued usage, as the battery is the key link in the system.

  Pros Cons
Offline • 2 means of delivering power
• Fewer service calls likely
• House power is main source
• Batteries (2nd source) are not cycled regularly
& may deteriorate without notice
• Power inverter is infrequently used & may fail
without notice
• Quality of power may be low & reduce motor
life expectancy
Online • Low cost
• Allows use of DC motor
• Battery is cycled often for longer life
• High quality of power to motor
• Battery is single point of failure
• If converter/battery fails, there is no power alternative
as the motor runs on DC electricity
• Likely requires more frequent service calls in or
out of warranty
Online with Switching • Battery is cycled often for longer life
• 2 independent means of supplying power
• Allows switching back to main house power
if batteries/converter fail
• Highlights failure prior to critical situation
occurring
• Fewer service calls likely
• Higher-quality input power to motor to
ensure long motor life if pure sine wave
inverter is used in the system
• Initial cost is higher

 

Choosing the Best Backup Match

An accessibility provider needs to ask whether a slightly increased cost will be justified by improved customer satisfaction for a system with higher reliability and availability if the battery does fail. In the end, happy customers are the key to good business, and for backup systems, the previous analysis leads to the conclusion that a power backup should not have a single point of failure that is known to have limited life and can unexpectedly fail — i.e., the battery.

The energy storage device or batteries should also be selected very carefully. Battery technology has come a long way in the last 15 years, and there are numerous good options. The primary considerations should be that most of these devices utilize power at a low level for a longer period of time. This means that lead-acid car batteries or others with similar characteristics, designed for short high-amperage discharge, should be avoided. Gel-type lead-acid batteries are preferred in most cases to avoid problems with outgassing, acid leakage and other environmental stability issues.

In addition to the architecture, consideration for any product in this area should include a review of the diagnostics that are available to indicate system status. Complex indicators that may make sense to an electrical or power engineer in the IT space, which also utilizes power backup systems, are not consumer friendly, especially in the mobility and accessibility space, where customers may not be electronics savvy. An advance warning service indicator is only useful if a customer/user takes action to correct it.

Power backup systems can be a substantial opportunity to increase revenue while providing a valuable service for clients, but you’ll need to consider the type of system carefully for how it will fail and what the criticality of that failure is. Not all products or manufacturers are looking out for the consumer, and in many cases they do not field the calls directly. That leaves the provider to work through the issues after a major incident has occurred and a customer is left stranded.

This article originally appeared in the October 2013 issue of Mobility Management.

About the Author

Graham Kawulka is partner and head of commercial operations for RAM Manufacturing Ltd.

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