Will my mobility scooter or electric wheelchair catch fire?
Many people worry, “Will my mobility scooter or electric wheelchair catch fire?” This fear stems from news of e-scooter and e-bike fires in recent years. Such incidents have made buyers of personal mobility aid (PMA) anxious about battery safety.
Around the world, authorities have raised alarms over lithium battery fires1. However, not all electric mobility devices carry the same fire risk. In particular, PMAs powered by traditional Sealed Lead Acid (SLA) batteries are far less prone to fire compared to those using lithium-ion batteries. This article explains the science behind why SLA batteries rarely ignite, reviews Singapore’s fire incident data (which shows virtually all fires involve lithium batteries), and discusses why using original battery components is critical for safety.
Battery Fire Incidents in Singapore: Lithium vs. SLA
Singapore has seen a surge in fires involving personal mobility devices (PMDs like e-scooters), power-assisted bicycles (PABs), and some mobility aids. In the last five years, there were 187 fires related to such devices2. Nearly half involved PMDs, 42% involved e-bikes, and about 12% involved PMAs2. Importantly, all these devices were powered by lithium-based batteries.
By contrast, traditional PMAs that use SLA batteries have a virtually clean record – there have been no known cases in recent years of an SLA-powered mobility aid erupting into fire. The absence of SLA battery fires is telling. Those PMA fire incidents almost invariably involved models that had been built with lithium-ion battery packs, not SLA.
Understanding Why Lithium Batteries Can Catch Fire
Lithium-ion batteries store high energy in a small package but come with a fire risk. These batteries contain flammable electrolyte liquids and reactive materials. If the battery malfunctions or is damaged, it can enter thermal runaway – an uncontrollable self-heating process that may ignite surrounding cells3.
Triggers include overcharging, physical damage, internal short-circuits, or manufacturing defects3. Once a lithium cell starts overheating, its flammable components may ignite, potentially leading to fire or explosion. About half of Singapore’s lithium-related device fires occurred during charging2.
Why Sealed Lead Acid (SLA) Batteries Are Far Less Fire-Prone
SLA batteries use a water-based sulfuric acid solution, not a flammable solvent. Their chemistry is stable. They do not enter thermal runaway or combust under normal failure conditions4. Even under abuse, SLA batteries tend to degrade or vent, not ignite.
They also have a lower energy density and are more tolerant of mishandling4. These characteristics make them ideal for applications where maximum safety is critical. SLA batteries have a long record of safe use in mobility aids (including Singapore).
Are SLA batteries safer than lithium batteries in mobility scooters?
Yes. SLA batteries are safer than lithium batteries for mobility scooters because they use a non-flammable electrolyte and cannot enter thermal runaway.
| Safety factor | Lithium battery | SLA battery |
|---|---|---|
| Electrolyte | Flammable organic solvent | Water-based, non-flammable |
| Thermal runaway | Can occur and spread between cells | Does not occur |
| Behaviour when damaged | May overheat, vent, catch fire | Typically vents or fails without ignition |
| Fire incident history in Singapore PMAs | Documented lithium battery fires | No known SLA PMA battery fires |
| Abuse tolerance (overcharge, knocks) | Low – needs strict protection | Higher – chemistry is more forgiving |
Key takeaway: For buyers who are worried about fires, SLA batteries offer much lower fire risk than lithium batteries, at the cost of extra weight.
The Importance of Using Original Batteries and Chargers
Many battery fires involve non-original batteries or chargers. In Singapore, 60% of active mobility device fires in 2023 were due to illegal modifications5. Cheap aftermarket batteries often lack safety protections and quality control found in original parts.
Original batteries include safety systems such as Battery Management Systems (BMS) to prevent overcharging. Non-original parts may use inferior cells and lack proper cut-offs, increasing risk6.
Authorities strongly advise against using third-party batteries. Devices should always be charged with the manufacturer-approved charger and never left charging unattended overnight6.
Choosing Between SLA and Lithium: What Should You Get?
If fire safety is your top concern, SLA-powered mobility aids are your best option. They are heavier but extremely stable. For daily home or flat use where lifting the device isn’t frequent, SLA models offer peace of mind.
If you need a lightweight or foldable model for travel, a lithium-powered device might be necessary. In that case, ensure it comes from a reputable brand, is safety certified, and always use the original charger and battery pack. Millions of lithium devices operate safely when used properly3.
Conclusion
SLA batteries offer a virtually worry-free experience regarding fire risk. They have a stable chemistry and a long history of safe use. Lithium batteries, while more portable, demand more careful handling.
Understanding these differences helps consumers choose the safest mobility aid for their needs. For those prioritizing safety over portability, SLA remains the gold standard.