Don't forget about the impact tests. These batteries are not known for taking much impact without damage. Being that it is warn, I would subject the pack/belt to all impact tests including those for hand held devices.
How are the battery pack recharged? While it is still in the belt? This can be the dangerous part. When cells go bad, usually they fail in a shorted condition. This then puts overvoltage on the remaining good cells during the charge cycle and causes them to overheat. I've seen cells get hot enough to melt the 94-V0 plastic case that is suppose to act as the fire enclosure. If the cells aren't the type with overpressure vents, they can even build up enough pressure to explode. The battery pack you describe sounds like the type that is meant to go inside of something or inside of an enclosure. I would recommend you design the battery pack like a notebook computer or cordless drill battery pack, where the fire enclosure is included and is designed to handle impact. Overcurrent and overtemperature protection, as previously recommended, is a must. Many years ago when laptop and notebook computers were coming out, there were a lot of recalls due to the battery packs. In one case I remember, salesmen would carry a spare battery pack for their notebook computer in their briefcase. The contacts for the pact wasn't protected, so they could short out on loose paper clips, turning them into a glow plug, and starting the briefcase on fire. Moral of this story is that you have to keep in mind how the user is going to use, charge, carry, store, and dispose of the battery pack. Have fun. Brian Kunde LECO Corp. ____________________Reply Separator____________________ Subject: RE: Fire Enclosure Design for NiCad Batteries Author: [email protected] List-Post: [email protected] Date: 12/17/02 10:18 AM Why does it need a Fire Enclosure? It is gets THAT HOT and is strapped to you waist (hot day - sweat-shirt!!!!) and your are up a ladder then you'll have more immediate problems than causing a building fire!!!! Please post the trade name so that we can all buy one for someone we dislike. : * } Meeting standards does not eliminate the need for a risk assessment. I suggest that the battery pack be made an Inherently Limited Supply - then many of your problems will go away. If you need high current then an OVER-TEMPERATURE non-resettable device might be an answer. Best regards Gregg -----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of Peter Merguerian Sent: Tuesday, December 17, 2002 5:11 AM To: "EMC-PSTC (E-mail)" < Subject: Fire Enclosure Design for NiCad Batteries Hello All, A battery belt made up of polymeric material similar to the one used to manufacture school bags, consists of NiCad batteries. The battery belt is to be used by builders in powering their battery tools during building construction. The NiCad batteries are made of nickel plated steel, with a thickness of 0.4 mm for the can and 1.2 mm for the cover. The 2 parts are insultated with a polyamide insulator ring. Can this construction of the batteries serve as the fire enclosure or should a separate enclosure of more robust construction be made for the batteries? This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 http://www.itl.co.il http://www.i-spec.com ------------------------------------------- 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: Ron Pickard: [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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- 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: Ron Pickard: [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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- 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: Ron Pickard: [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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
