What is UL?
UL (Underwriters Laboratories) is a safety consulting and certification company headquartered in Northbrook, Illinois. It maintains offices in 46 countries. UL was established in 1894 and has participated in the safety analysis of many of the last century's new technologies, most notably the public adoption of electricity and the drafting of safety standards for electrical devices and components.
UL provides safety-related certification, validation, testing, inspection, auditing, advising and training services to a wide range of clients, including manufacturers, retailers, policymakers, regulators, service companies, and consumers.
UL is one of several companies approved to perform safety testing by the US federal agency Occupational Safety and Health Administration (OSHA). OSHA maintains a list of approved testing laboratories, which are known as Nationally Recognized Testing Laboratories.
UL is the trusted source across the globe for product compliance. Benefiting a range of customers - from manufacturers and retailers to consumers and regulating bodies - we抳e tested products for public safety for more than a century.
And now, we can offer one of the conformity assessment industry抯 broadest portfolios of capabilities and certification marks. Our unique mix of local expertise in global markets and deep industry knowledge helps bring safer products to markets faster than ever before.
UL Standards for Safety
UL has developed more than 800 Standards for Safety. Our Standards for Safety are essential to helping ensure public safety and confidence, reduce costs, improve quality and market products and services. Millions of products and their components are tested to UL's rigorous safety standards with the result that consumers live in a safer environment than they would have otherwise.
As of January 2007, UL Certification customers can access UL and ULC Standards at www.ULStandards.com. Other features include establishing a customized standards library with e-mail notifications of all updates, including revisions and proposals, to UL Standards material in your library. Not sure if your company already uses the Standards Certification Customer Library website, then contact customer service at 1-888-UL33503 (1-888-853-3503).
Sales of UL Standards Materials
UL Standards for Safety are now available from comm 2000. To provide greater flexibility to UL clients and others worldwide, comm. 2000 offers four easy ways of obtaining UL Standards and Standards-Related Products and Services anytime! Many of UL's Standards are American National Standards that utilize Standards Technical Panels as the consensus body. Information on UL's Standards Technical Panels is available at http://ulstandardsinfonet.ul.com/stp/index.html.
Collaborative Standards Development System
UL's Collaborative Standards Development System (CSDS) provides online access for review and submitting information for UL's Standards development process. General access is available for information on STP meetings, submitting proposals, and proposals available.
UL's Standards Department website, http://ulstandardsinfonet.ul.com, contains information about UL Standards. Information available includes:
• Current Catalog of Standards,
• Standards pricing information,
• Standards bulletins,
• Scopes of UL Standards,
• Scopes of all UL Outlines,
• Harmonization Information, and
• National Electric Code (NEC) changes and proposals to STP
The Standards Department Web site is routinely taken down for maintenance, every Monday from 5:30 a.m. to 12:00 p.m. GMT.
What are the key features of Lithium-ion battery
In many ways Lithium is almost the perfect cell chemistry and many variants exist. Practical Lithium based rechargeable batteries were first demonstrated in the 1970's, and they are now used in very high volumes in low power applications such as mobile phones, laptops, cameras and other consumer electronic products. They have many attractive performance advantages which make them also ideal for higher power applications such as automotive and standby power.
1. High cell voltage of 3.6 Volts means fewer cells and associated connections and electronics are needed for high voltage batteries. (One Lithium cell can replace three NiCad or NiMH cells which have a cell voltage of only 1.2 Volts)
2. No liquid electrolyte means they are immune from leaking.
3. Very high energy density (About 4 times better than Lead acid). For example a 3.5 ton electric powered LDV light van uses 750Kg of Lead acid batteries. The same capacity could be provided by less than 200 Kg of Lithium batteries, allowing the van an increased payload of half a ton. Alternatively. The van's range of only 50 miles could be quadrupled by using the same weight of Lithium batteries.
4. Very high power density. As above.
5. Very small batteries also available. Solid state chemistry can be printed on to ceramic or flexible substrates to form thin film batteries with unique properties.
6. Low weight
7. Can be optimised for capacity or rate.
8. Individual cells up to 1000Ah capacity available.
9. Can be discharged at the 40C rate or more. The high discharge rate means that for automotive use the required cold cranking power or boost power for hybrid vehicles can be provided by a lower capacity battery.
10. Fast charge possible.
11. Can be deep cycled. The cell maintains a constant voltage for over 80% of its discharge curve. It thus delivers full power down to 80% DOD versus 50% for Lead acid. This means that in practice, for a given capacity, more of the stored energy is usable or that the battery will accept more starting attempts or boost power requests before becoming effectively discharged.
12. Very low self discharge rate. Can retain charge for up to ten years.
13. Very high coulombic efficiency (Capacity discharged over Capacity charged) up to 95% or more. Thus very little power is lost during the charge/discharge cycles.
14. No memory effect. No reconditioning needed.
15. Tolerates microcycles
16. Long cycle life. 1000 to 3000 deep cycles. (But see Lithium titanate below). Cycle life can be extended significantly by using protective circuits to limit the permissible DOD of the battery. This mitigates against the high initial costs of the battery.
17. Does not need reconditioning as do nickel based batteries.
18. Variants of the basic cell chemistry allow the performance to be tuned for specific applications.
19. Available in a wide range of cell constructions with capacities from less than 500 mAh to 1000 Ah from a large number (over 100) of suppliers world-wide.
How to maximize battery performance?
1. Break In New Batteries: New batteries come in a discharged condition and must be fully charged before use. It is recommended that you fully charge and discharge the new battery two to four times to allow it to reach its maximum rated capacity.
2. Prevent the Memory Effect: Keep the battery healthy by fully charging and then fully discharging it at least once every two to three weeks. Exceptions to the rule are Li-Ion batteries, which do not suffer from the memory effect.
3. Keep the Batteries Clean: It's a good idea to clean dirty battery contacts with a cotton swab and alcohol. This helps maintain a good connection between the battery and the portable device.
4. Exercise the Battery: Do not leave the battery dormant for long periods of time. We recommend using the battery at least once every two to three weeks. If a battery has not been used for a long period of time, perform the new battery break in procedure described above.
5. Battery Storage: If you don't plan on using the battery for a month or more, we recommend storing it in a clean, dry, cool place away from heat and metal objects. Ni-Cd, Ni-MH, Li-Ion and Lipo batteries will self-discharge during storage; remember to break them in before use.
6. For Laptop Users: To get maximum performance from your laptop battery, fully optimize the notebooks power management features prior to use. Power management is a trade off: better power conservation in exchange for lesser computer performance. The power management system conserves battery power by setting the processor to run at a slower speed, dimming the screen, spinning down the hard drive when it's not in use and causing the machine to go into sleep mode when inactive. The notebook users guide will provide information relating to specific power management features.
How long will the new main battery power the laptop?
How long do batteries last?
How are batteries rated? What are volts and amps?
Can Li-ion polymer battery be contacted with water?
Can I use Li-ion polymer batteries mixing with other battery types?
REACH is the Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals. It entered into force on 1st June 2007. It streamlines and improves the former legislative framework on chemicals of the European Union (EU).
The main aims of REACH are to ensure a high level of protection of human health and the environment from the risks that can be posed by chemicals, the promotion of alternative test methods, the free circulation of substances on the internal market and enhancing competitiveness and innovation.
REACH makes industry responsible for assessing and managing the risks posed by chemicals and providing appropriate safety information to their users. In parallel, the European Union can take additional measures on highly dangerous substances, where there is a need for complementing action at EU level.
Electrodes-Energy Power Trade-Offs
For a given cell chemistry and within the space available inside a given cell case, the cell performance can be optimised for capacity or power.
Increasing the surface area of the electrodes increases the cell's current handling capability. Thus the cell can both deliver more power and it can be charged more quickly.
Increasing the volume of electrolyte in the cell increases the cell's energy storage capacity.
The prime trade off is between the area of the electrodes and the volume of the electrolyte which can be contained within the volume available in the cell case.
High power cells require electrodes with a large surface area as well as enlarged current collectors which take up more of the available space within a given cell, displacing the electrolyte and reducing the cell capacity.
The effective surface area of an electrode can be increased without increasing its physical size by making its surface porous and using materials with very fine particle size. This can increase the effective surface area of the electrodes by 1000 to 100,000 times enabling higher current rates to be achieved.
High capacity cells require large volumes of electrolyte which must be accommodated between the electrodes. This has a double effect in reducing the cell power handling capability. First, the electrodes must be smaller and further apart to make space for the extra electrolyte and hence they can carry less current. Secondly, because of the increased volume of the electrolyte, it takes longer for the chemical actions associated with charging and discharging to propagate completely through the electrolyte to complete the chemical conversion process. (More details are given in the section on Charging Times).
As an example - Lithium Ion cells optimised for capacity may typically handle peak currents of 2C or 3C for short periods, whereas Lithium Ion cells optimised for power could possibly deliver pulsed currents of 30C to 40C.
Four of the most common constructions are shown below. Over the years there have been many thousands of variants of these basic types used for many different cell chemistries.
High power cells usually incorporate special safety devices. See "Designed in" safety measures.