How To Prevent An eBike Battery Fire? Important Tips!

The battery is the most vulnerable part of the e-bike. Due to a hard fall or incorrect charging, the battery can catch fire and is then almost impossible to extinguish. The message from experts: be kind to the bicycle battery. Handle it with care.

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All new e-bikes have a lithium-ion battery. Why is this battery so popular? A major advantage is that this type of battery can store a lot of energy at a low weight. In addition, there is an extremely low self-discharge. The lithium-ion battery is also very good at rechargeable. However, there is a major drawback to the lithium-ion battery: it can burn and is not very economical.

What makes a lithium-ion bicycle battery so flammable?

A bicycle battery is made up of a large number of round cells that are connected to each other. You can compare it to a stick flashlight in which you have to put batteries. Such a cell in a bicycle battery consists of an anode (negative electrode) and cathode (positive electrode) with an electrolyte in between as a conductor and a separator (separating membrane between the anode and the cathode).

These four parts are neatly rolled up like ‘sheets’ to form a cell. If you look at the composition of the cell, it’s like a small chemical factory. And one of the products used in this factory is very reactive: lithium. It is quickly flammable. If everything goes according to the rules, there is nothing to worry about. But sometimes things can go wrong.

What can go wrong with a lithium-ion bicycle battery?

The cause of a battery fire can often be traced back to a fall. Batteries don’t like hard hits. If a gust of wind blows your bike over, the battery may still look fine on the outside. However, damage may have occurred inside that could lead to a fire. The effect of the smack on the street is that a cell can burst. ‘A short circuit can then occur, a peak current, between one of the products that make up a cell. It causes a violent chemical reaction. ‘You can compare it with fuel from a rocket. It needs a small inflammation and then the reaction will continue on its own.’ 

The ignition as a result of that chemical reaction starts in one cell and then spreads to the other cells in the bicycle battery. This domino effect is called thermal runaway and can last quite a long time. The phenomenon of deep discharge (a really completely empty battery) can also cause such a thermal runaway. Fortunately, the battery management system (BMS) prevents the battery from being over-discharged and overcharged. 

Despite the BMS, self-discharge can still happen if you leave your e-bike unused in the shed for months. Furthermore, the Institute for Physical Safety (IFV) advises not to park the e-bike in full sun, but in the shade. IFV is the institute of and for the safety regions in strengthening fire services. So it is good to rest from time to time on a bike ride but look for a shaded spot for your eBike.

What should you do if your bicycle battery starts to smoke?

Hard fact, a thermal runaway cannot be physically extinguished. Removing the fuel of the fire – the first cell – is not possible, and the chemical reaction produces oxygen itself, so skimming or extinguishing it with powder makes no sense. The fire continues until the battery is burned out.

Extinguishing with water causes a reaction with lithium to produce explosive gas. The smoke that is released is very toxic. It’s a cocktail of dangerous substances. Hydrogen fluoride in particular is a highly toxic substance that, if exposed, can cause serious health damage through inhalation and skin contact. So stay away!

It is best to quickly bring the battery out in the initial phase. In that initial period, the battery can also be placed in a bucket of water for cooling. Leave it there for hours. For the large batteries in electric cars, the fire service is diligently looking for innovative extinguishing agents that are better suited for extinguishing burning lithium-ion batteries.

How often does a battery fire occur in an electric bicycle?

According to recent studies, a disaster scenario involving bicycle batteries rarely occurs. ‘In relation to the number of lithium batteries that we have at home – smartphones, and lawn mowers are also equipped with them – the number of fire incidents is minimal. Parties from the e-bike sector also confirm the impression that it only occurs occasionally.

What should you do as an e-biker to prevent a thermal runaway?

Handle your battery with care. All e-bike manufacturers have a detailed explanation on their website how to handle the battery with care. Prevent fall damage. Even without visible damage, something can be broken inside.

Also charge in a good place and full is full. Do not leave the charger connected to the bicycle battery unnecessarily. A tip from the fire brigade is to install a fire detector in the room where an eBike battery is charged.

Is it dangerous to keep an eBike battery in the house?

Store a battery at room temperature. An eBike battery cannot withstand too high and too low temperatures. The advice of all e-bike brands is not to leave a battery in an uninsulated shed, especially not in autumn and winter when the e-bike is hardly used or not used at all. A battery can be deeply discharged (slightly) faster due to that temperature that is too low and can become useless.

You need to charge the battery until it is full and then unplug the charger. It may sound strange, but don’t charge an eBike battery in any rooms like in the bedroom, but simply in the hallway. If something goes wrong, for example the fire alarm goes off, the battery can still be taken out quickly.

Burning bicycle batteries are difficult to extinguish.

What are bike shops and manufacturers doing to keep batteries safe?

The serious battery fires in July 2018 and mid-January 2019 at Stella Cycling gave the bicycle sector a shock. The storage of thousands of batteries entails great risks. Stella has built a special bunker in Nunspeet. An aerosol extinguishing system ensures that the chemical reaction stops. 

This is how you recognize a broken eBike battery:

• The battery is leaking fluid
• (Excessive) heat
• Strong odor
• Smoke
• Sparks