Lithium-ion batteries and lab/home safety. - Page 1
Forum section: electronics / general

author: Synthtech
author_rank: Regular Contributor
timestamp: January 09, 2019, 08:00:59 pm
content: I just purchased some IC’s and tantalum caps from a respected local electronics supplier that I order from most every week and added in an item that they had on special on their site because it looked useful for the workshop - a ruggedised 10W LED work light that doubles as a power bank for re-charging USB devices like phones. It uses IRC18650 batteries internally and is charged via a micro-usb cable. It is in a really good form factor and case for my purposes as a very bright work light that I can place inside larger pieces of equipment as I work on them. Useful tech!I see that even though it is distributed by an Australian wholesaler it has no C-Tick labelling which is required on a re-chargeable device of this type so it presumably has had no safety testing either. It got me to thinking - as we get more and more devices in our workshops/labs and homes that use reasonably large capacity lithium-ion battery packs from China (my Micsig tablet oscilloscope for example) there must be an increasing risk of getting poorly made batteries that can potentially short internally and burn, especially larger capacity batteries.In Australia we had a spate of fires from re-chargeable “hoverboard” batteries failing a couple of Christmases ago and the airlines here banned them. Maybe I am being overly paranoid but I do wonder about the increasing number of high energy batteries that we are filling our houses and work places with, often from no-name suppliers in China. Those things hold a lot of energy and if a factory cuts corners with their production I would not want one anywhere near me. Maybe I am being too cautious, I guess that trades use them all the time in their hand tools and they seem to be OK.

author: Whales
author_rank: Super Contributor
timestamp: January 09, 2019, 08:42:55 pm
content: Interesting perspective on energy density: the amount of electrical energy you can get out of a LiCo/LiMn/sim lithium battery is still only about 1/10th of the energy you get from burning the same size or weight in wood.https://en.wikipedia.org/wiki/Energy_densityOf course burning the lithium batteries might be another story, and wood variesa lotI believe LiFePO4's might be safer in regards to avoiding catastrophic sudden energy release, but they're not as popular. It would be nice to see the industry try to change over (I'm assuming the cost differences are mostly due to popularity). Many products use under-size or low quality cells to begin with, so I don't think the capacity per unit volume differences would be mostly noticed.FWIW I keep my spares in a metal box on my shelf that I've lined with fibro. If I ever do have a problem I hope this might help me contain it. And I keep the hell away from any product with a lithium primary (eg CR123), I've read too many horror stories on CandlePowerForums regarding permanent lung damage and HF acid mist.I don't think I've ever seen nor thought of a C-tick on a battery here until now. I'm so used to expecting them to be uncaring imports. Sidenote: be wary of the difference between the two types of 'tick' you can get, they look similar to consumers but mean very different things.

author: Synthtech
author_rank: Regular Contributor
timestamp: January 09, 2019, 09:29:49 pm
content: Interesting, I hadn’t heard about the safety issues with CR123 batteries, I will go look that up. As for energy density it would be interesting to work out the threshold where a lithium ion battery could be expected to reach a temperature where it would combust rather than just overheat and swell as it rapidly discharges. There are videos of burning android phones on the web and their batteries aren’t that big....

author: Whales
author_rank: Super Contributor
timestamp: January 09, 2019, 10:12:11 pm
content: Definitely read up about lithium primaries (such as CR123's). Don't ever try to recharge those.I've read all sorts of numbers for max safe temps on lithium-ions before they start a self-sustaining reaction. Off the top of my head: 100, 114, 130degC. I suspect it varies depending on model, manufacturer and safety margin. It probably has no relationship to overall battery size, only construction and materials (edit: and state of discharge, chemical wear, etc).

author: amyk
author_rank: Super Contributor
timestamp: January 09, 2019, 10:18:50 pm
content: Quote from: Synthtech on January 09, 2019, 09:29:49 pmThose are usually internal shorts. The electrolyte is flammable and that's usually what releases the most energy in a battery fire, after being ignited by the stored energy.

author: eKretz
author_rank: Frequent Contributor
timestamp: January 15, 2019, 05:24:56 pm
content: Quote from: Whales on January 09, 2019, 08:42:55 pmYeah, good luck recharging the wood though! And don't forget the energy spent to cut and process it.