Charging your electric scooter battery: Best practices to extend its lifespan

Properly charging an electric scooter battery involves following a few key guidelines: using the charger specifically designed for it, ensuring the battery is neither too hot nor too cold, placing it in a well-ventilated and supervised location, and disconnecting it once it's fully charged. These practices extend the lifespan of the battery cells and significantly reduce the risk of incidents. Charging is, in fact, the time when a lithium battery is most stressed. Here's a detailed explanation of each rule and the reasoning behind it.

The right charger

A lithium battery charger initially delivers a constant current, and then, as the battery approaches full charge, it maintains a constant voltage while the current decreases. Its final voltage must precisely match the number of cells in series in the battery: for example, 84V for a "72V" battery with 20 cells. A charger with a final voltage that is too high will overcharge the cells; one that is too low will never fully charge the battery.

The French National Institute for Occupational Safety and Health (INRS) recommends using the original charger or, if that is not possible, a charger that is suitable for the battery in terms of voltage and capacity, and that follows the supplier's recommendations. A generic "universal" charger is not a suitable option. Also, ensure that the charging current does not exceed the limits of the charging port and the Battery Management System (BMS): in some BMS systems, the charging input has a much lower limit than the output.

Our scooter batteries are delivered without a charger; if the voltage is the same, the original scooter charger will work. For fast charging of battery packs designed for it, see our chargers, including the UltraCharge 4000W, and the guide fast charger: saving time and limitations.

The temperature: neither too hot nor too cold

• After a ride, especially a vigorous one, the battery will be hot. Charging it immediately adds heat to the existing heat: let it cool down first.
• In cold weather, a lithium-ion cell charged below 0°C is at risk of metallic lithium deposition on its negative electrode. This deposition is irreversible, leading to a loss of capacity and weakening of the cell. Allow the battery to return to room temperature, which can take several hours for a large pack. Many Battery Management Systems (BMS) actually prevent charging below a certain temperature.

Location and Monitoring

Charging is the moment when a latent defect can manifest. Here are some guidelines, based in part on recommendations from the French National Institute for Occupational Safety and Health (INRS) and emergency services:

• On a hard, non-flammable surface (such as tile or concrete), away from textiles, wood, and cardboard
• Never in a hallway, stairwell, or in front of an emergency exit
• Battery and charger not included, store in a well-ventilated area
• Ideally, perform this operation in a room equipped with a smoke detector, and remain nearby
• Unplug it at the end of the charging cycle, rather than leaving it plugged in overnight.

The reasons for these precautions are explained in our guide on lithium battery fires and prevention.

How much should I charge it?

A lithium battery degrades more quickly when it remains at 100% charge for extended periods, or when it is completely discharged. For daily use, it's best to recharge before the battery is completely empty and to avoid leaving the battery fully charged for days, as this can shorten its lifespan. Partial recharges pose no problem: there is no "memory effect" with lithium-ion batteries.

There is an important exception: most Battery Management Systems (BMS) balance the cells at the end of the charging cycle by dissipating the excess charge from the most charged groups. A battery that is never fully charged almost never balances itself. Therefore, it is important to regularly perform full charges, leaving the charger plugged in for a while after the "full" indicator lights up, under supervision. The operation is detailed in our guide on BMS and balancing.

Charging connectors

An oxidized, loose, or blackened charging connector can overheat during charging. Check it periodically, keep the cap in place while riding, and never connect a wet connector. A connector that feels hot to the touch during charging should be replaced.