Is there a safe way to charge Lithium-ion batteries? (guide)

It takes more than common sense and care to charge lithium-ion batteries safely. You can do a few things to minimise the potential for catastrophic thermal runaway fires.

First, many of these tips are common sense, which has a real sting in its tail. Because common sense means a basic level of practical knowledge, we all need to survive. Things like not putting your hand in the fire, playing with live electricity, or putting the cat in the microwave.😲

But as we have found, from Does insurance cover a lithium-ion battery fire? Maybe and probably not, Insurers can use a lack of common sense as a valid reason not to pay. Why? Unless you live in a cave without access to social media and world news, you will have heard of the ever-growing risks of lithium-ion batteries and how to minimise risk.

In case you did not know, Lithium-ion batteries are classified as dangerous goods under the Australian Dangerous Goods Code, imposing extra conditions on their use, transport, storage and disposal. Ignoring any of these can give an insurance company a valid reason not to pay.

The ACCC has released its long awited report on Lithium-ion battery safety. We will analyse that soon.

What is a Wh (Watt Hour) used in battery sizing?

The watt-hour rating is calculated by multiplying the voltage (V) by the ampere-hours (Ah). If amperage is shown as milliampere hours (mAh), divide the mAh value by 1,000. It is called OHMS law = Volts x Amps = Watts.

For example, if a smartphone has a 5000mAh 3.6V battery, the Wh is 3.6 x 5000/1000 = 18Wh. A laptop typically has a 14.6V, 70Wh battery. That is 70Wh/14.6V = 5Ah or 5000mAh.

Is it a real problem, and will it affect me?

As we stated in Large-capacity Lithium-ion batteries will end in death there are rechargeable Lithium-ion batteries in:

  • Bluetooth portable earphones, headphones, speakers
  • Razors, toothbrushes, vapes, and beauty devices
  • Wearables like smartwatches
  • Digital cameras, Radios
  • Household Appliances
  • Smartphones – up to 5000mAh (note issue with older micro-USB phones)
  • Tablets and e-readers like iPad, Android and Kindle
  • Laptops up to 20V/5A/100W batteries in laptops (this increases for workstation laptops)
  • Stick and robot vacuums or mops
  • Power tools, drills, sanders, planers
  • Garden tools, trimers, blowers, electric mowers
  • UPS and Portable power banks
  • E-scooters 36V/25W/900W, 48V/35A/1680W or 60V/35A/2100W
  • E-skateboards 36V/4A/145W (or more)
  • E-bikes 36V/125A/540W, 48V/21A/1000W, 60V/40A/2560W
  • Electric vehicles
  • Solar battery storage – up to 10kW

Each has a different risk profile. Most of the current issues are with larger-capacity lithium-ion batteries over 30V.

Charge Lithium-ion batteries – Common sense to reduce risk

Do not charge

  • Larger capacity devices indoors. Undercover outdoors (like a carport, balcony, or patio) reduces fire risk and the risk of total loss due to thermal runaway.
  • When temperatures <5° or >30°. The ‘chemistry’ changes.
  • If the battery pack or cables are damaged in any way
  • If the battery pack has been subject to moisture (rain or flood)
  • On or near flammable materials.

For example, place a ceramic tile under the charging phone on your bedside table. Make sure overhanging bedclothes and curtains are more than a metre away. Never charge it on a fabric surface, as it does not dissipate heat.

If charging an e-bike/scooter/skateboard, ensure it is on bare cement at least 5 meters from flammable surfaces (including flammable overhead ceilings).

Before charging

  • Check that all leads and connectors are in good condition, e.g., not frayed, no signs of corrosion, etc.
  • There is no sign of battery pack swelling.
  • If the device can limit charging to 80%, enable it. Lithium-ion is less stressed if operated between 20-80% charge.

After charging

  • Remove the device from the charger when complete.
  • If the battery pack feels hot to touch >45°, get it checked it immediately.
  • Unplug the charger and Store the device away from flammable items.

If a fire occurs

  • Call 000 fire emergency and declare it is a Lithium-ion battery fire.
  • Do not attempt to move the item, as it can explode.
  • Do not use water as this is an electrical and chemical fire.
  • Have fire suppression handy. At the very least, a fire blanket can help to contain flames.
  • A D-Class fire extinguisher can assist if you can envelop the battery pack with foam.
  • Try not to get within 5 metres, and remember that Lithium-ion battery fires can last hours and spontaneously erupt at any time.

Disposal of Lithium-ion batteries

Do not place them in the bin; they can get into the rubbish stream and cause serious issues later.

Do not transport Lithium-Ion batteries in hot “trunks’ or ‘boots’ where temperatures can reach over 50° in the sun.

For larger items, call your local Council for disposal options. For smaller removable batteries, tape the terminals (stops shorts), preferably put them into a glass or plastic container (like Corning ware or Tupperware – not airtight), and dispose of them at Planet Ark outlets.

Charge Lithium-ion batteries – Risk factors

The risk increases with the number of ‘cells’ in the battery pack. A single cell (cylinder) will burn out quickly. E-bikes/scooters/skateboards are so explosive because they use dozens of cells in a confined space.

Bluetooth devices – risk low

Headphones and speakers are relatively low risk, provided you remove them from the charger when full. If you use them on mains power, limit use to a few hours. These do not have power circuits for 24×7 charge and use (unless specified).

Beauty devices – risk low

These usually have a single-cell battery and pose a low risk, provided you remove them from the charger and only recharge when empty.

Wearables – risk low

Most are designed to sit on a charge pad that operates off a USB-C charger. The single most effective risk reduction is to use a 5V/.5A/2.5W charger.

Digital cameras, radios, etc – risk low

Remove the charger when charging is complete. Set an alarm approximating charging time.

If batteries are removable, do so when not in use. Store in a non-flammable environment.

Phones – risk low

Apart from Samsung’s now infamous Note 7, the incidence of smartphone fires when in use is rare. Risk increases over time.

  • Charge on a non-flammable surface and at least 2 meters from flammable materials.
  • Remove the charger when charging is complete. This may not be practical if charging overnight when you are sleeping. Use a smart plug that allows scheduling (a good idea for any Lithium-ion device).
  • If your phone has an older micro-USB connection, do not charge it unattended; remove the charger when complete. This connection type has very little overcharge protection.
  • Use Qi Wireless charging if your phone supports it. Qi is intelligent and only gives the phone what it needs, so you can leave it on the charge pad. Apple uses MagSafe wireless charging.
  • Look in your phone settings for Battery and see if there are Safe charge options (OPPO calls this Wise Charge) that learn your charging habits and slows down overnight charging to give you a full charge in the morning.
  • Where a phone does not come with a USB-C charger (Apple, Samsung, Google Pixel and Nokia), buying any RCM C-Tick approved charger from Belkin, Ankler, A-Logic, etc. is safe. The retailer will advise suitable models.
  • Where a phone comes with a charger, ensure it has RCM C-Tick or return it and demand an approved one. The charger’s fine print will show charging voltages if you need another charger.
  • Always use cables that are overrated for wattage. The 2W cable that often comes with phones is prone to overheating. Buy a thicker, preferably fabric braided, 3 or 5W (or higher) cable from Anker, Belkin, Cygnett, Comsol, or another reputable brand.

For laptops and tablets – risk low

Laptops have largely replaced desktops and mini-towers; most are designed to stay plugged in 24×7. But you can take some precautions (Windows laptops only).

  • Never place a laptop on fabric, vinyl, padded or other synthetic fabrics, as they can block ventilation slots under the device. Suitable surfaces are glass, ceramic tile, or timber. Expelled air can be above 50°, so ensure the surface or surrounding materials are not affected.
  • If possible, raise the laptop off the surface to allow greater ventilation. For example, use four Lego blocks.
  • Go to Settings>System>Power and battery. Turn your screen off after 3 minutes of non-use, and put the device to sleep after 5 minutes. This considerably reduces heat. Change your power mode to ‘best battery’ rather than best performance.
  • Enable the battery saver at 20% remaining.
  • Some have a setting to limit charging to 80% – enable that.
  • If you always use power and the battery is full, turn the charger off when you stop using it.

Smaller household items – risk medium

The problem with household items is that many are generic Asian brands with little regard for RCM C-Tick certification.

  • Ensure the charger has RCM C-Tick, or it is not approved here. Do not believe CE, FC, or RoHS marks are acceptable.
  • Always use the charger it came with, especially if it has a plug-style fitting. Do not buy generic chargers and multi-adapter plug packs.
  • Charge on a fire-restraint surface away from fire-prone materials.
  • Always remove the charger when full.

Stick and robot vacuums or mops – risk low

Many of these come with a charging base, stand, or cradle and are designed to be permanently connected.

The main issue is to turn them off at the wall if you are away for a month or more.

Power tools, drills, sanders, planers – risk low

Most of these have detachable batteries and separate charger receptacles. Like any charger, look for the RCM C-Tick. Always unplug after charging.

Garden tools, trimers, blowers, electric mowers – risk low

Most of these have a separate charger and cable. Check for the RCM C-tick. Always unplug after charging.

UPS, USB-C power banks (<22,000mAh) portable power stations – risk depends on battery type

Portable power banks had a lousy reputation for catching fire. Product Safety Australia lists 58 recalls since 2021. Most were about overheating during charging with a risk of fire. Some were very reputable brands that fell foul of Asian manufacturing.

If it is Lithium-Ion (as most cheap ones are), then it is a potential high-risk bomb when charging, transporting (including dropping) or in use. Take every precaution and charge it on a non-flammable surface at least five metres from flammable items. When transporting, take care to keep it cool <30°. Keep it dry (regardless of IP rating) and cool out of direct sunlight. CyberShack will no longer review these.

If the device uses Lithium iron phosphate (LFP or LiFePO4), they have a very high tolerance to temperature, high stability and do not experience thermal runaway. We consider the risk low, and you can charge indoors away from flammable materials.

Portable Power Stations are a recent phenomenon, and we only review Lithium iron phosphate (LFP or LiFePO4) ones.

E-scooters 36V/25W/900W, 48V/35A/1680W or 60V/35A/2100W

E-skateboards 36V/4A/145W (or more)

E-bikes 36V/125A/540W, 48V/21A/1000W, 60V/40A/2560W

Clearly, this is where all the negative publicity is aimed at. Like any device, there are good and bad brands, manufacturers, and retailers.

The key here is that quality and safety are often sacrificed to meet a price point. And as 99% of these come from Chinese factories, it is hard to know what compromises have been made.

  • Avoid generic brands not sold by a major retailer or only sold online.
  • Insist on proof that the charger is RCM C-Tick certified (it will be printed on the charger and hopefully the battery pack.
  • Never use a third-party charger. Some devices come without a charger, and you should insist that the vendor sell you an approved charger. If you need to buy a charger, don’t seek out the lowest cost; seek out ones that appear well-made and from reputable companies.
  • Look for devices that have removable battery packs that can be charged in safer locations.
  • Look for devices that use Lithium iron phosphate (LFP or LiFePO4) regardless of higher cost.
  • Do not charge indoors under any circumstances.
  • Charge on a fire-retardant surface like cement.
  • Make sure there are no flammable materials within 5 metres (preferably 10)
  • As constant supervision may be tricky, use a smart plug to turn off the charger when charged.
  • Install a smoke/fire detector where you usually charge. A smart one can send notifications to your smartphone.
  • Install a security camera that reacts to changes in heat (PIR detection). Arlo PIR combines Thermal Sensing and Motion detection.
  • Set an alarm every 30 minutes to manually check the charging process. This may be hard when charging can take 5+ hours, but lack of supervision is considered negligent and gives the insurance company a valid reason not to pay.
  • Disconnect after charging.

Electric vehicles – risk low

There is not enough data yet to build a risk profile. You will already be paying considerably more for insurance than a petrol vehicle.

The risk varies with charging technology. Slow 240V charging overnight does not stress the battery. Fast charging does, but for a relatively shorter time, and you are generally on the road again.

The prime risk is physical damage from a crash or driving over something that may pierce the battery housing. Driving through flood waters can damage the battery. If you suspect damage, drive it to your automotive dealer and have it thoroughly checked.

Some insurers now ask that dedicated charging areas (like your garage) be made of cement, have a smoke alarm, and be fire-proofed with the removal of all flammable substances. Why? Thermal runaway can generate 1000° heat and result in total loss if a structure is made from timber.

Some insurers are beginning to ask for a Car Fire Blanket. These $3500, 6 x 8m x 30kg blankets are made to be pulled over a burning car and contain the fire – not put it out. A 9kg Class D fire extinguisher won’t do any good against an EV fire but may help stop flames from spreading to other items.

Solar battery storage – up to 10kW – high-risk

Solar batteries and solar installations have a higher recorded risk of fire. Read LG ESS solar home battery recall (Urgent update November 2022). LG’s short fix is to limit charging to 75% while waiting for the free replacement.

There are a few issues:

  • Don’t buy cheaper Lithium-ion battery packs
  • Do buy Lithium iron phosphate (LFP or LiFePO4) instead that meet UL 9540A performance criteria (few do)
  • Don’t skimp on the inverter – micro-inverters are safer than string inverters.
  • Use your management App regularly to discover any anomalies that may lead to failure. Update firmware regularly.
  • Even if the battery has an IP rating, install it under cover and out of direct sunlight.
  • Avoid installation inside a building or roof cavity or with flammable materials within 5 metres. If you can’t avoid this, look at fireproofing the area, install a smoke alarm and a Thermal PIR camera.

CyberShack’s view – Is there a safe way to charge Lithium-ion batteries? Not really

Lithium-ion has always been a flawed but energy-dense (a.k.a. cheap) way to store energy. As technology progresses, newer technology will have more safeguards.

The problem is that Lithium-Ion batteries are largely unregulated from design, manufacture, transport, use and disposal. Frankly, it is all about price – the lower the price, the more risk it has. And as we discovered, there is a huge ‘remarking’ counterfeiting business to offer cheaper goods.

The USA has UN DOT 38.3 & IEC 6228 to prevent dodgy Lithium-ion cells transported to its shores. It also has UL 1642 for individual cell safety and UL 62133 for battery packs, but these only apply to that market. Yet e-scooter/bike/skateboard fires are just as prevalent there – all from uncertified battery packs and chargers.

IATA has air-travel passenger rules prohibiting >160Wh Lithium-ion batteries (up to larger laptop computers) from carry-on or checked baggage. The limit applies to all personal transport devices. Some airlines now enforce 100Wh maximums.

While Australia has an RCM C-Tick regulation, it applies to the chargers (the things you connect to mains power), not the batteries and is largely ignored by online merchants. But it is all we have, and you must check the chargers first.

Our advice is to use more common sense.

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