A major concern arises if static electricity or a faulty charger has destroyed the battery’s protection circuit.Such damage can permanently fuse the solid-state switches in an ON position without the user knowing.A battery with a faulty protection circuit may function normally but does not provide protection against abuse.Another safety issue is cold temperature charging.Consumer grade lithium-ion batteries cannot be charged below 0°C (32°F).Although the packs appear to be charging normally,plating of metallic lithium occurs on the anode while on a sub-freezing charge.
To prevent the infiltration of unsafe packs on the market,most manufacturers sell lithium battery cells only to approved battery pack assemblers.The inclusion of an approved safety circuit is part of the purchasing requirement.This makes it difficult for a hobbyist to purchase single lithium-ion cells off-the-shelf in a store.The hobbyist will have no other choice than to revert to nickel-based batteries.I would caution against using an unidentified lithium-ion battery from an Asian source,if such cells is available.
The plating is permanent and cannot be removed.If done repeatedly,such damage can compromise the safety of the pack.The battery will become more vulnerable to failure if subjected to impact,crush or high rate charging.Asia produces many non-brand replacement batteries that are popular with cell phone users because of low price.Many of these batteries don’t provide the same high safety standard as the main brand equivalent.A wise shopper spends a little more and replaces the battery with an approved model.Figure 1 shows a cell phone that was destroyed while charging in a car.The owner believes that a no-name pack caused the destruction.
The safety precaution is especially critical on larger batteries,such as laptop packs.The hazard is so much greater than on a small cell phone battery if something goes wrong.For this reason,many laptop manufacturers secure their batteries with a secret code that only the matching computer can access.This prevents non-brand-name batteries from flooding the market.The drawback is a higher price for the replacement battery.I have to disappoint the shoppers by directing them to the original vendor for a brand name pack.
Considering the number of lithium 18650 battery used on the market,this energy storage system has caused little harm in terms of damage and personal injury.In spite of the good record,its safety is a hot topic that gets high media attention,even on a minor mishap.This caution is good for the consumer because we will be assured that this popular energy storage device is safe.After the recall of Dell and Apple laptop batteries,cell manufacturers will not only try packing more energy into the pack but will attempt to make it more bulletproof.