How long is a battery’s life?
Maarten Steinbuch, professor at TU Eindhoven (technical university in Eindhoven, the Netherlands) studies the possible lifespan of an electric battery. The lifespan of a battery is calculated as ending when the battery goes under 80% of its original capacity.
“According to abundant scientific research a normal battery has a life-cycle of 1000 to 2000 charging cycles”, says Steinbuch. “With life-cycle we indicate the span where the battery still has 80% or more from her original capacity.”
“The second important term here is charging cycle. A charging cycle is the addition of the discharging and the charging of a battery. Partial charging can be added: if you charge a battery two times from 20 to 70% every day, you use one whole charging cycle every 2 days.”
“The lifespan of a battery is of course dependent of the use. Discharging and loading a battery to the bottom and the top (100%) uses a battery more. Temperature is key here: without a cooling system a battery will age quicker.”
“An example: we use our smartphone practically until empty and charge it until 100%. It has no additional cooling. So normally a smartphone battery has a lifespan of some 3 years with around 1000 charging cycles.”
“An electric car with a range of 300 km and a smart cooling system will do better. Normally it can take at least 1.500 charging cycles, which means 450.000 km. After that you still have 80% of battery capacity or 240 km. So the lifespan of a battery is 50% higher than that of an internal combustion engine (ICE).”
When you drive 15.000 km a year your battery accordingly has a life expectancy (in the car) of 30 years. After that she can still be used for other purposes, where quick charging and ‘full’ capacity are less important.
Reality even better
For more than 5 years TU Eindhoven and professor Steinbuch have been monitoring a few hundred drivers of electric cars. The average battery degradation lies at somewhat 2.000 cycles, so more than expected.
“Most of our EV drivers are using their battery in the most economic way and don’t charge every day until 100% when this is unnecessary. For them and for us the battery is a very valuable gem”, concludes Steinbuch.