You might not know it, but rechargeable batteries can be dangerous. No, we’re not talking about flaming smartphones, due in no small part to making batteries thinner and thinner with fewer ways for the heat to escape. We’re talking about the risk involved with a shorted battery.
Rechargeable cells have been around for decades, and as time marches forward, new technologies have been developed as well as ways of packing more power into the same amount of space. Today’s NiMH (nickel metal hydride) and Lithium-ion cells are a far cry from the AA NiCad™ batteries popular in the 1970s.
Nickle and Cadmium
NiCads put out 1.2 volts, about 20% less than the rated capacity of a standard alkaline battery or zinc-carbon cell, but they hold that level of output much longer than alkaline batteries. NiCads can be recharged up to 2,000 times, and their storage capacity tends to decrease slowly over time. NiCad batteries lose 10-20% of their capacity for each month in storage (heat is a contributing factor), so your rechargeable flashlight might not last very long when the power goes out a few months after it was last charged. NiCads should be recharged within 3 months when possible, 4 months at the most to avoid draining batteries to the point of no return.
NiCad batteries are popular in radio controlled cars, planes, and boats, as well as power tools. A typical AA NiCad cell has about 1.8 amps.
The worst thing you can do to a NiCad battery is to overcharge it, which will reduce its capacity. The next worst is to completely drain it, at which point it may no longer accept a charge.
NiCad batteries first rose to popularity in the consumer market in the 1970s as drop-in replacements for zinc-carbon and alkaline cells.
The Batteries of NiMH
The greatest benefit of nickel-metal hydride cells is that they can store 2-3x as much energy as the same size NiCads while providing 1.2 volts. One drawback compared to NiCad is that NiMH batteries can only be charged about 500 times – which is still a lot.
The first consumer NiMH batteries came to market in 1989, and their energy density has made them a popular replacement for NiCad in many circumstances. They have also become very competitive in price.
The first rechargeable lithium batteries came to market in 1991, two years after NiMH cells. They have a very high energy density, which is why they are used in Teslas (over 7,100 cells per car) along with other electric cars, and in hybrids.
Unlike the other types of cells we’ve discussed, lithium-ion batteries have a nominal charge of 3.6V, the same as three NiCad or NiMH cells. Because of their high voltage and high energy density, lithium-ion carries the highest risk. Those flaming smartphones? All due to lithium-ion batteries.
Be careful not to bend or crush lithium-ion batteries. Over an 8-year period (2009-16), 195 incidents involving explosion or fire caused by lithium-ion batteries in e-cigarettes were reported by US media. Of these incidents, 62% took place while vaping or while the e-cig was in someone’s pocket.
To put this in perspective, vaping has resulted in an average of less than 25 fire and explosion incidents per year, while cigarette smoking is responsible for about 90,000 fires resulting in over 1,600 injuries and over 500 deaths annually. (NFPA)
Although Underwriters Laboratories (UL) has developed standards for lithium-ion battery safety, UL Standard 8139, Electrical Systems of Electronic Cigarettes, evaluates only the battery and electrical controls of an electronic cigarette. At present no regulation, code, or law applies to the safety of the electronics or batteries in e-cigarettes. There are no requirements that e-cigarettes be subjected to product safety testing by a Nationally Recognized Test Laboratory, such as UL. The FDA is considering handling regulation of the batteries and electronics used in vaping rather than passing it along to UL.
The US Fire Administration would like to see lithium-ion cells banned from use in e-cigarettes. Expect the vaping industry to resist that, as using NiMH cells would create bulkier, heavier devices.
Play It Safe
Regardless of the numbers, every incident is a potential tragedy. Some have been severely injured by their vaping hardware, although no deaths had been reported as of 2016. In most incidents, only one person was injured. But as the number of vapers has grown, so has the incidence of fires and explosions.
Some simple precautions will help. Don’t put your e-cigs in your pants pocket. Sitting on it may bend the device and the battery within it, not to mention the chance of leaking e-juice (and thus nicotine) on you, which is a real hazard. Don’t put e-cigs in the front pocket either. You don’t want a burn there or a nicotine leak.
For slim devices, a shirt pocket or jacket pocket is a much better bet. For larger, heavier devices, figure something out to protect both you and your hardware.
Higher capacity batteries are nice – they last longer. Higher capacity batteries are risky – they contain more reactive chemicals and thinner layers between them. The highest capacity batteries are the most convenient but at the same time the most hazardous in the rare event something does go wrong.
No Loose Batteries in Your Pocket
Rechargeable battery safety means storing the batteries in their devices, chargers, or a properly designed storage case so there is no chance of a short circuit. This is especially true of 9V “transistor” batteries because the positive and negative contacts are right next to each other.
Never ever put rechargeable cells loose in your pocket with keys or change – a short will make them hot and they may burst into flames if the short continues. If you don’t have a case, wrap them together with a rubber band and put them in a plastic bag so the contacts are protected.
Loose batteries in your pocket that short can burn you or your clothes.
Don’t Buy Unmarked Batteries
Batteries run the gamut from well-known brand names to completely unmarked batteries. If the manufacturer is not willing to put its name on its product, consider that a warning that whoever made it isn’t going to stand behind the product. Also, you have no way of knowing who made an unmarked battery.
Buy your batteries from a reputable source, because there are fakes out there that look like the name brand products. Because they are selling a third-rate product by pirating a first-rate brand’s reputation, you are at the same risk as you would be with unmarked batteries – perhaps even more, since it is marked with a name you trust. This is a case where trademark infringement can endanger you, and companies that sell the pirated product are breaking the law.
Those incredible online deals may be too good to be true. Some signs of piracy are lower quality printing, typos and poor grammar in the packaging (if it’s even packaged), and cheap packaging. Companies such as Sony and Panasonic put their reputation on the line with every product they make, and that applies to every aspect of packaging as well.
If your friendly neighborhood vape shop is trying to sell you unmarked batteries, or even ones that just don’t have a brand, beware. Will the store stand behind the product in the unlikely event that the battery explodes or combusts? Don’t count on it.
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- Nickel-cadmium battery, Wikipedia
- Nickel-metal hydride battery, Wikipedia
- Batteries And Coins Don’t Mix, geocaching.com
- Electronic Cigarette Fires and Explosions in the United States 2009 – 2016, US Fire Administration
NiCad is a registered trademark of SAFT Corporation, and it has become an informal label for NiCd batteries regardless of brand.
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