Doug, Thanks for the advice. I'll be having some discussion with the design team to bring out your pointers. As they are currently still in the designing stage.
But my current concern is when we talk to the Li-ion batteries suppliers, what compliance documents should we request from them. At least to proof that the batteries are indeed safe or meeting the minimum requirements. I'm new to Li-ion batteries and not sure that standards that it needs to conform to. UL1462 & UL2054 are standards which was found in UL website. Is there a European standard for Li-ion batteries? Is there a battery directive? If yes, what standards is applicable? CE mark required? Regards Koh "Massey, Doug C." wrote: > Well, I haven't seen anybody weigh in on this yet, so here goes. > > First of all, Li-Ion batteries have tremendous energy density. I recently > watched some videos of Li-Ion cells failing an overcharge test, and it was > really impressive. These things looked like a roman candle going off ! They > would make great highway flares. So here's my advice and hopefully I can > answer some of your questions. > > 1. Vent. Period. If a cell vents inside your device, the pressure build up > inside your battery pack enclosure could be tremendous if an adequate > venting mechanism is not provided. > > 2. In addition to providing reliable overcharge, overvoltage, & reverse > polarity protection, consider controlling the maximum discharge current as > well. With today's cells, most (probably all) incorporate a PTC device built > into the cell to interrupt excessive current. I personally would not > recommend relying solely on this protective device alone. However, that > built-in device will allow you to pass the rapid discharge test of clause > 4.3.21 (UL1950 3rd Ed. reference), where you must defeat any current or > voltage limiting device in the battery load circuit. > > 3. Protection circuits for Li-Ion are typically based on an IC controller > along with some discreet components making up the circuit. Last time I dealt > with getting a Li-Ion pack approved, that IC is not UL recognized, and we > could not find any control chips that are. Expect to be asked by the test > house to provide technical assistance in determining worst-case faults in > that circuit, so that they can ensure the safety of that control circuit > under any conceivable single fault condition. Expect the test house to focus > more on the battery and associated control circuits than anything else in > your portable device, just as they might focus more on the primary side of > an AC supply. The greatest energy source, and greatest safety hazard, in > your product will be the battery. > > >>What standards must these Li-ion batteries needs to comply before we > >>purchase them? UL2054 or UL1642 standards or both ? What about European > standards ? > 4. UL 1642 is the applicable U.S. standard for cells. UL 2054 could be > applied as well to a Li-Ion battery pack as well, but in your case, the > requirements within the overall product standard (60950?) should apply. Not > sure about the equivalent CENELEC standard. > > 5. When discussing battery issues, please refer to them as "cells" or > "battery packs", so that we all know whether you mean an individual cell or > a pack made up of two or more connected cells. I am making assumptions that > when you say "battery", what you mean is, a removable battery pack, but I > guess it's conceivable to have a widget that the cells are permanently > mounted inside of, although I can't conceive why anyone would do that, since > the typical life of a Li-Ion is going to be around 500 charge-discharge > cycles. In the case of a Li-Ion battery pack, the only information required > on the pack is the voltage and the IEC symbol referring the user to the > operator's manual, where you will be required to have statements regarding > the proper replacement of the battery, statements telling the operator not > to disassemble, crush, or incinerate the battery pack, and not to operate > above a certain temperature (usually around 200 C - this is very important, > since people are always using their ITE devices in a friggin walk-in oven at > 392 F to crush, disassemble, or incinerate their Li-Ion battery packs). This > max temperature comes from the conditions of acceptability for the cell > itself, and will vary between brands. Alternately, all of this info can be > on the battery pack itself, but it's a lot of text that you may not be able > to fit - 60950 does allow the warnings to be in the operator's & service > guides. > > >>We might want the supplier to put our company name on the battery, > >>what can we do (or request from the supplier) to protect ourself on > >>liability issue? > > If you figure out a way to get your company excused from any liability > resulting from use of a product that your company produces, please let me > know. Name or no name on it, if you sell that product, you could be liable > for any damages. As always, independent third party evaluation of your > product's compliance to the accepted national safety standards of the > country in which you are marketing the product, along with diligent & > demonstratable product and process control in the manufacturing of said > product is your best defense against product liability. But all that still > doesn't ultimately relieve you of liability. > > Hope this helped. Please note that the opinions expressed above are my own > opinions and not neccessarily that of my employer. > > Doug Massey > LXE, Inc. > > -----Original Message----- > From: Koh N. G. [mailto:[email protected]] > Sent: Wednesday, May 16, 2001 10:07 AM > To: EMC-PSTC > Subject: Li-ion Batteries > > Greeting everyone, > Can anyone advice on the requirement for Li-ion batteries? > > We are currently designing a prototable device which has Li-ion > batteries built within. > The battery is being charged via AC-to-DC adaptor. We are purchasing the > Li-ion batteries from suppliers. > There will be safety circuitry for overcharging the batteries, as well > as overvoltage and opposite polarity protection. > > As this is our first time handling Li-ion batteries, any advice from the > group would be appreciated > 1) What standards must these Li-ion batteries needs to comply before we > purchase them? > UL2054 or UL1642 standards or both ? What about European standards ? > 2) What marks needs to be on the batteries? And which standard do these > marks calls? > 3) What are the compliance documents that we need to request from the > supplier? > > A bit tricky question is > 4) We might want the supplier to put our company name on the battery, > what can we do (or request from the supplier) to protect ourself on > liability issue? > > Regards > Koh > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
