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:koh...@cyberway.com.sg] 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. 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