Hi Rich, Thanks for your advice. From a couple of battery pack explosion investigation, the result revealed that the cause was the short-circuit in jelly roll that developed during the service life. We are unsure if the new standard have developed a reliable method to qualify the production units since there is no new standard issued after the Sony battery pack recall. Recently, HP also had a smaller scale of battery pack recall. It seems this is still not under control in this industry.
Regards, Scott From: Richard Nute [mailto:[email protected]] On Behalf Of 'Rich Nute' Sent: 2009年7月10日 2:42 To: 'Scott Xe'; [email protected] Subject: RE: How to determine if battery-operated product is safe or not Hi Scott: The major areas of safety of battery-operated product are: 1) the discharge circuits; 2) the charge circuits; 3) the chemical process during discharge; 4) the chemical process during charge. The circuits must be designed such that the chemical processes are not stressed. However, once the chemical process is stressed and results in damage to the separator, then there is nothing that can be done via the circuits to control the resulting chemical reaction; the energy must be expended. The "safe-ness" depends on the RATE the chemical energy is expended. A high rate may result in an explosion; a low rate may result in mild over-heating. World-wide, many standards organizations are addressing circuit requirements that will not stress the chemical process. Battery manufacturers are honing their processes to make the batteries (the chemical processes) less susceptible to physical, thermal, and electrical stresses. With the exception of high-impedance keep-alive button batteries, there is hardly a battery that will not overheat during excessive discharge rate or excessive charge rate. Even alkaline batteries have been known to start a fire when discharged at too high a rate. The only answer I can give is to follow the standards development, and apply the latest and greatest drafts -- even though they are not yet standards. Best regards, Rich > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Scott Xe > Sent: Thursday, July 09, 2009 7:38 AM > To: [email protected] > Subject: How to determine if battery-operated product is safe or not > > > We have an USB rechargeable battery-operated video clip/MP3 > player. As battery-operated products do not fall into LVD > directive, what can we apply the basis to determine the > product safe or not? Looking at historical safety hazard > reports on the market, there was not much any recall on this > type of products except the explosion of rechargeable battery > pack. However, the possible explosion of rechargeable battery > pack cannot be picked up by LVD directive or dedicated > UL1642/2054 battery cell/pack standards. Otherwise, Sony did > not need to recall millions of battery packs and the said > standards are not required the review. What is potential > hazard do we need to look at this type of products? As the > safety hazard is tied with power energy, is there any > reference that there is no safety concern if the power energy > is below certain level? > > Thanks, > > Scott > > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
