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Lithium Battery Safety

by Ezra Auerbach

In this article I’ll provide an overview of some of the safety considerations associated with lithium batteries.  There are specific standards that govern batteries and energy storage systems (ESS). The one that will be most relevant to Laquetians is UL 1973 which is a chemistry agnostic battery safety standard. The test procedure includes mechanical safety, thermal cycling, exposure to moisture and, perhaps most important, fire exposure testing. All batteries purchased for home installations should be certified to UL 1973 standards. Part of the requirements for attaining a UL standard is that the manufacturer must provide installation and operating instructions. Read and follow them; they contain important information about safe installation and operation.

   

There are a variety of chemistries within the lithium battery “family” and some of them have less-than-stellar reputations. NMC (Nickel Manganese Cobalt) use materials that are mined in very economically depressed areas by very oppressed workers. These batteries have the highest energy density and have been used extensively in EV applications. They have a higher risk of thermal runaway catching fire. Many e-bike batteries use this chemistry for the extra energy density. This choice of chemistry is largely why they frequently burn when charging. The quality of the battery management system (BMS) is more critical with NMC batteries. A high quality BMS that is matched to the specific battery makes a significant difference with respect to fire risk. More on BMS later.

   

Virtually all the lithium batteries made for home applications are Lithium Iron Phosphate (LiFeP04 or LFP for short). This chemistry is somewhat less energy-dense and is also considerably safer and uses less controversial materials. It is very hard to make these batteries burn. Hard but not impossible – which is why a safe installation is so important!  

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