Charging an electric motorcycle at home: outlet, charger, charging time, and safety

A light electric motorcycle can be charged at home using a standard wall outlet with the supplied charger. The charging time is simple to calculate: the energy to be put back into the battery divided by the charger's power, plus a little extra time for the end of the charge. Two points require attention: the outlet and the electrical circuit, especially with a fast charger, and the location where you charge, for safety reasons. Here is what you need to know.

How long does a charge take?

A charger provides roughly constant power during the bulk of the charge. By dividing the energy to be put back into the battery (in watt-hours) by this power (in watts), you get the order of magnitude for the charging time in hours. Example calculation: 2000 Wh to put back with a 500 W charger takes about 4 hours.

The end of the charge takes a little longer: when the cells approach their maximum voltage, the charger gradually reduces the current. The BMS takes this opportunity to balance the cells, meaning it brings all cells to the same voltage. A full charge from time to time is useful for this balancing. For full details, see our guide on best practices for charging a battery, the principles of which are the same for a motorcycle.

The outlet and the electrical circuit

A domestic outlet and the circuit powering it are designed for a specific current. A light motorcycle charger generally stays within these limits, but it draws current for hours: a worn-out outlet, a coiled extension cord, or an undersized power strip can heat up.

• Plug directly into a wall outlet in good condition, without a power strip.
• If an extension cord is essential, choose one with a sufficient cross-section and uncoil it completely.
• A warm outlet or plug after charging is a warning sign: have the installation checked.

With a fast charger, the scale changes. Our 4000 W "GTK" type UltraCharger recharges a 2 to 3 kWh battery in about an hour, whereas an original charger would take all night. At 230 V, 4000 W represents a little over 17 A: the charger must be plugged into a 32 A outlet, like that of a stove, or on a dedicated line. Have the installation checked by an electrician if you have any doubts.

Fast charging and the battery

Fast charging puts more stress on the cells. Fast charging should be reserved for batteries designed for it: cells, BMS, and connectors must be sized for this current. On a battery not designed for it, it accelerates aging and can cause connectors to heat up. Even on a compatible battery, regular slow charging gives the BMS time to balance the cells.

Where and how to charge safely

Lithium battery fires are rare, but violent and difficult to extinguish. A few simple actions significantly reduce the risk:

• Charge in a ventilated area, ideally a garage, on a non-combustible floor, away from flammable materials, and never in an emergency exit.
• Install a smoke detector nearby, and avoid leaving it to charge unattended for long hours, especially at night.
• Do not charge a very cold or very hot battery: let it return to room temperature.
• Never charge a battery that is swollen, has been dropped heavily, smells like it is burning, or has been exposed to water: isolate it outdoors, away from everything, and have it checked.
• Unplug the charger once charging is complete.

Our guide on lithium battery fire prevention details these precautions. In co-owned buildings, charging in a parking lot or common area raises other issues, addressed in our guide on charging in co-owned buildings.