Total battery capacity vs. usable battery capacity

Electric cars will all have a listed battery capacity, such as 40kWh, 52kWh, and larger sizes up to 100kWh. It is important to note that this capacity is not always fully useable. Generally, the useable portion of the battery is 95-99% of the total capacity of the battery. 

Why is the whole battery capacity not usable?

Batteries used within electric vehicles are usually made of lithium-ion, and these batteries do not always respond well to being fully charged or fully depleted. The unusable portion of the battery acts as a buffer to ensure the cells do not suffer increased degradation over the course of their lifetime, making sure you're able to continue enjoying maximum efficiency. 

The unusable portion of the battery can vary between cars, due to the differences in cell design between manufacturers. 

Why does my car say it's fully charged if I can't use the whole battery

Your cars dashboard/infotainment screen will only show you the charge level of the usable capacity. So when you see a charge level of 100%, your usable portion will be fully charged, but the cells will not be at their total designed capacity. 

A better way of explaining this is when your battery shows as being depleted at 0%. If you've seen some EV test videos online, the testers will still be able to drive their cars around for a few more miles even with the car warning it's completely out of charge and to safely pull over. This is possible due to the car retaining power in the unusable portion. The onboard computers will still eventually cease power transfer to the drivetrain, but will retain energy to continue protection of the battery cells. 

How can I find out the size of my usable battery capacity?

We recommend speaking to your dealer or consulting your vehicle handbook to confirm the usable battery capacity of your vehicle. Usually both figures are available, however some manufacturers may only state one or the other as the battery capacity without confirming which is which. 

A good resource to check is the Electric Vehicle Database. We've compiled a few of the vehicle makes and models below :

If you still require support then please contact us by emailing support@char.gy or call us on 0800 086 9606.