Beware budget battery reliabilty
Saft has issued a warning to lighting manufacturers after laboratory tests of two Chinese-made rechargeable nickel-cadmium batteries showed them to be unsuitable for emergency lighting applications.
Saft has issued a warning to lighting manufacturers after laboratory tests of two Chinese-made rechargeable nickel-cadmium batteries showed them to be unsuitable for emergency lighting applications.
The company became concerned when engineers discovered that the inferior materials in the positive electrode and separator meant that neither battery was able to hold its charge for anything like the required minimum period.
Dave Pattison, National Sales Manager for Saft Rechargeable Battery Systems says: "We understand the pressures that emergency lighting manufacturers face to be competitive".
"Batteries account for up to 30% of the cost of the finished product, and a saving of 20% is certainly appealing".
"Nevertheless, if the batteries chosen do not last or perform as they should real damage will be done to the reputations of lighting manufacturers directly".
"We are also concerned that it will reflect badly on the battery business as a whole".
The batteries concerned are coming into Europe from China and are simply not fit for purpose in emergency lighting.
"They may be adequate for less demanding applications like torches or toys", says Pattison, "but the reliability of emergency lighting where batteries must hold their charge for at least four years is a very different matter".
"Failure at the critical moment could be literally be a matter of life and death".
"What lighting manufacturer would voluntarily take the risk of legal action or having their reputation damaged?".
To establish its case Saft has tested the permanent charge endurance of its own high temperature VT D-size battery against two Chinese-made competitors.
The first test was carried out according to the IEC60285 standard, which includes an ageing period of six months at 70C which equates to use of the battery in the application over four years at 40C.
The Saft cells retained a high level capacity - more than 2.5Ah.
The competitor's model not only showed signs of severe cell degradation, but its capacity had decreased significantly and was down to less than 0.5Ah after 6 months and showed a voltage drop on all discharge curves even after two months of overcharging.
Another "competitor" battery would not even pass the basic requirements of the less severe ICEL test let alone the more demanding requirements of IEC60285.
In two critical areas, the construction of the positive electrode and the separator, the differences are clear and show why these cells are not suitable for use in an emergency light.
At the heart of the batteries that pass the stringent safety tests, like those from Saft, is a sintered positive electrode.
This provides a stable electrical conductor, produces no capacity loss in long storage, copes well with long storage at high temperatures and is mechanically stable in permanent charge.
By contrast the poorer quality products employ foam technology that is not stable and suffers irreversible capacity loss over time.
Compare also the construction of the separator used in the Saft batteries and that used in the inferior products.
The one used by Saft retains a stable permanent charge and provides a strong barrier between the positive and negative electrodes.
The development of this separator has taken Saft many years to perfect.
Poorer quality batteries suffer from oxidation of the fibres at high temperature which, combined with low weight and bad binding, makes them vulnerable to short circuiting.
Pattison concludes: "Reputable battery manufacturers have made huge investments in technology as well as materials".
"These factors make the performance difference and ultimately it is reliability that the users of emergency lighting are paying for".
"If a cheap battery fails to deliver the power when it's needed then it could be the most expensive purchase that you will ever make".
Not what you're looking for? Search the site.
Tel +44 1279 772550
-
NiCd cells combine the best of both worlds
Saft has developed the new VNT range of NiCd cells to satisfy the needs and requirements of specific applications such as emergency lighting. -
Novel drain cleaners gain battery power
The Trojan Tool company's cordless sewer and drain cleaner provides a powerful and safer alternative to AC powered devices that electrocute hundreds of plumbers every year. -
High-energy rechargeable batteries cycle well
Saft has extended its VH "super high energy" series with two new nickel-metal hydride (Ni-MH) cylindrical cells - the D-size VH D 9500 and the F-size VH F 1500. -
CD "handbook" features battery selection guide
The new Saft Rechargeable Battery Systems handbook is a full guide to the selection and use of rechargeable batteries. -
Ni-MH cell handles heavy cycling
Saft's new VH F nickel-metal hydride (Ni-MH) cylindrical cell has been developed specifically for applications requiring high-energy rechargeable batteries for use in frequent cycling conditions.
Articles by product category
- Consultancy and Services (903)
- Machine Building (4,517)
-
Engineering Design Software (6,179)
- Engineering Design Software (12)
- 2D CAD software (200)
- 3D CAD software (1,157)
- FEA and structural analysis software (369)
- Fluid, thermal, noise, vibration software (334)
- Simulation, modelling, validation software (914)
- Rendering, visualisation, styling software (196)
- Materials design and moulding design software (151)
- Process, instrumentation, automation software (258)
- Electrical design software (164)
- Publishing and documentation software (229)
- Maths, charting, statistics, QA software (317)
- Data, document management software (310)
- CAM, CNC, production management software (568)
- File conversion software, data capture (351)
- PLM and collaboration software (649)
-
Drives, Motors and Controls (3,361)
- Drives, Motors and Controls (1)
- Precision Motors and Gears (411)
- Industrial Drives/Controls (1,276)
- Linear Drives and Motors (114)
- Industrial Motors (497)
- Stepper and Servo Drives, Motors, Controls (1,060)
- Small Mechanical Components, Joining, Tools (1,975)
-
Control and Instrumentation (5,028)
- Plantwide control (1,324)
- Plant- and Machine-Wide Communications (1,174)
- Smaller-Sized PLCs (387)
- CNC and Motion Controllers (184)
- Mid-range and Large PLCs (201)
- Power Supplies, Uninterruptible Power (562)
- HMIs/Operator Interfaces (294)
- Logic Controllers, Timers and Relays (96)
- Cabling, Conduit, Signal Conditioning (806)
-
Monitoring, Measurement and Quality (5,459)
- Monitoring, Measurement and Quality (1)
- Data acquisition Software and Communications (494)
- Data Acquisition Hardware and PC I/O Boards (472)
- Electrical and Electronic Testing, PAT Equipment (630)
- Form/co-ordinate, optical, vision instruments (703)
- Gauges, Indicators and Instruments (440)
- Data loggers (422)
- Materials testing equipment (421)
- Telecomms/network test equipment, software etc (154)
- Testing and Calibration Services and Information (500)
- Testing, analysing and monitoring equipment (1,222)
-
Electrical and Electronic Equipment Design (4,160)
- Batteries, chargers and circuit protection (555)
- Connectors, Terminals, Busbars, Slip Rings (679)
- Enclosures and Equipment Cooling Fans (709)
- Knobs, Handles and Enclosure Hardware (420)
- PCs and Embedded Systems (798)
- Electrical and Electronic Subassemblies (369)
- Electrical and Electronic Components (630)
-
Materials and Processing (2,963)
- Materials and Processing (5)
- Materials and components (2,215)
- Rapid Prototyping (458)
- Materials processing and testing (285)
-
Engineering Industry News, Resources (6,093)
- Engineering Industry News, Resources (4)
- Engineering Business News, Views (388)
- Engineering Exhibitions, Events (562)
- Engineering Conferences (425)
- Engineering Seminars (400)
- Engineering Industry Developments, Awards (633)
- Engineering Guides, Newsletters (349)
- Engineering Recruitment, Employment (219)
- Engineering Training Courses (433)
- Engineering Education, Resources, Standards (838)
- Engineering Industry Reports, Surveys (597)
- Electronic Resources for Engineers (278)
- Health and Safety Legislation (402)
- Health and Safety Strategy, Risk Assessment (113)
- Health and Safety Consultancy, Software (175)
- Health and Safety Events, Training, News (277)
-
Powertrain Design (3,598)
- Powertrain Design (2)
- Bearings (939)
- Chains and belts (326)
- Gears, brakes, couplings and engines (1,441)
- Hydraulic Components (471)
- Lubricants (418)
-
Capital Equipment (3,387)
- Capital Equipment (1)
- Manufacturing Machinery and Plant Equipment (468)
- Production line blowers and fans (62)
- Compressors and Air Treatment (510)
- Electronics Manufacturing, Tools, Instruments (192)
- Electrical hardware (131)
- Machinery and Production Equipment (1,093)
- Robotics, Handling and Storage (930)
-
Sensors (7,080)
- Sensors (8)
- Accelerometers and Vibration Sensors (427)
- Loadcells, Force Sensors, Torque Sensors (699)
- Pressure sensors (621)
- Flowmeters and Flow Sensors (618)
- Level Sensors and Leak Detectors (527)
- Linear Position Sensors (399)
- Rotary Position, Tilt and Angular Sensors (546)
- Proximity Sensors (700)
- Gas, Chemical, Radiation, Magnetic Sensors (284)
- Humidity and Environmental Sensors (152)
- Temperature sensors (612)
- Vision and Colour Sensors (1,384)
- Barcode Sensors (103)
- Valves, Pumps, Process Hardware (3,623)
