Safely charging e-bikes and scooters
Posted on 18th September 2023
‘Thermal runaway’ can cause lithium-ion batteries to catch fire when they self-heat uncontrollably, leading to toxic fumes, fires and explosions.
Even when they’re put out, lithium-ion battery fires can start again, which is why they are so dangerous.
Faults in the lithium-ion cells leading to short-circuits are often the cause.
The problem is so worrying that the London Fire Brigade has recently launched a #ChargeSafe campaign.
External causes of lithium-ion battery failure
One common cause is overcharge or over-discharge due to incompatible chargers or a faulty battery management system (BMS). Water inside the battery casing can also cause short-circuits or failure of built-in protection measures. Physical crushing and punctures or impacts such as repeatedly hitting kerbstones can lead to faults. Extreme temperatures can also build-up pressure due to gases, making batteries unstable, producing toxic and flammable gases.
E-bike and scooter risks and safety measures
The #ChargeSafe campaign aims to reduce the number of e-bike and scooter fires. It highlights the dangers related to charging, storing and modifying them and their batteries.
The BMS for lithium-ion batteries monitors and controls the cells, regulates their charging, the voltage and current in each cell. Many also monitor the temperature of the cells. The system protects the cells from over-charging and over-discharge by switching off the load when the battery voltage reaches a certain level. Discharging lithium-ion batteries too deeply can cause damage. This can mean they don’t hold a charge and, in some cases, they can catch fire while in use.
However, there’s a lot of information online about how to modify or bypass the battery BMS to increase battery charge or discharge and bypass the manufacturer’s safety systems.
If you have an e-bike or scooter the #ChargeSafe campaign recommends some steps you can take to reduce the risks:
Make sure your e-bikes, scooters and batteries don’t block your exits. Ideally store them in a shed or garage.
Let your battery cool before charging it.
Only use batteries and chargers that meet UK safety standards. Look for clear UKCA or CE marks and the manufacturer/importer details. Confirm they meet standards such as EN 15194 for electrically assisted pedal cycles (EPAC).
Use the correct charger for your battery and make sure to buy from a reputable source.
Never leave your battery to charge when you are out or asleep.
Turn off your charger and unplug your bike, scooter or battery when fully charged.
Never place batteries on soft furnishings.
Look out for warning signs such as smells, excess heat, changes in battery shape or colour or batteries no longer holding their charge.
Fit heat and smoke alarms in the area where you charge your batteries.
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