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Lithium Ion Battery Safety

Despite all of the fear-mongering in the news every time a cheap electronic device catches fire, Lithium Ion batteries really are one of the safest battery chemistries available.  You only have to put your critical thinking hat on for a moment to realise that these batteries are in pretty much every rechargeable item in your house (mobile phones, laptop computers, iPads, Tesla cars, etc) because they are safe and efficient.

Lithium Ion batteries have an operating voltage of 3.0-4.2 volts.  When Li-ions explode, it is usually because the user has allowed the voltage to move outside of this range.  If it drops below 3.0v, the battery can oxidise internally and cause it to short circuit.  If the battery is charged above 4.2v, the battery can overheat and will vent when temperature approaches 150C.


This is why I tell everyone who is new to Li-on to only buy protected batteries.  'Protected' means that the battery has internal circuitry that prevents overcharging and over-discharging.  It effectively switches the battery off when the charge drops outside the 3.0-4.2 volt range. It also pays to spend a little bit more and get a high quality Japanese or Korean made cell.  These will have a longer life and actually charge quicker than cheaper Chinese cells.

You can double up on safety by making sure your charger has charge protection also and, if it is a 240v charger, that it carries the Australian standard C-Tick.  This will ensure that the charger has been tested to Australian safety standards.  The overcharge protection in your charger will act as a backup in case the circuitry in your battery fails.  Another tip is to never leave a charging battery of any type unattended.

When buying Li-ions, as I said earlier, make sure the battery is clearly labelled as protected or includes the letters IC or ICR (for internal circuitry) in the description.  If buying online, make sure you are buying from a reputable Australian dealer as there are an incredible number of dodgy, fake batteries on eB@y and Am@zon. Some of the cheapest Li-ion batteries you see on eB@y may just be much smaller cells wired up and rewrapped in a tube to look like an 18650.  Not only will the capacity be lower than stated but they are very dangerous.  A real 18650 battery should weigh approximately 45g.  If your battery weighs less than 42g or more than 46g, odds are it is fake.  Also, be aware that the maximum capacity of an 18650 battery is about 3800mAh and anyone claiming higher than this is telling porkies.  If the price seems too good to be true, it probably is.

Stick to these basic rules and you will be able to use your lithium ion batteries safely and with peace of mind -

  • Buy lithium ion batteries from a trusted source
  • Use only higher quality Japanese or Korean made cells
  • Make sure your li-ions have built in overcharge, overdischarge and over-current protection
  • Use a charger that also has inbuilt charge protection
  • Do not leave charging batteries unattended
  • An 18650 will weigh approximately 45 grams