The 80% Sweet Spot: The Perfect Charge for Your EV Battery

The 80% Sweet Spot: The Perfect Charge for Your EV Battery

November 19, 2023
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elon-musk

Did you know your electric vehicle (EV) battery reaches its Sweet Spot at 80% charge?  That’s right.  This is one of the few times in life we can climax at 80% for maximum longevity, drivability and safety.

 

But why not 100%?  Contrary to popular belief, electric vehicle batteries perform better when they aren’t fully charged. 

To help clarify the 80% Sweet Spot concept, I’ll share an analogy from Elon Musk.

 

Picture yourself driving into an empty parking lot. At this stage, it’s easy to find a parking – but, as the parking lot fills up with vehicles the chances of finding a space diminish.  That last 20% is akin to finding the last remain parking spaces. It takes up time and can cause unnecessary duress.

 

To maximize the lifespan of your EV battery, it’s crucial to comprehend the underlying chemistry of the lithium battery that powers your vehicle.

 

Striking the right balance and getting the perfect charge can significantly impact your car’s performance, longevity, and overall efficiency. 

 

To understand this we need to start with the basics

Charging Porsche Taycan

Battery Chemistry
Lithium-ion batteries, commonly used in EVs, behave non-linearly when it comes to charging. The charging speed is typically faster in the initial stages, up to around 80%. As the battery approaches its maximum capacity, the charging rate slows down to protect the battery and ensure safety.

 

Voltage Limitations

Charging a battery involves increasing its voltage to a certain limit. Once the battery reaches a high state of charge, the voltage approaches the upper limit allowed for safety reasons. Charging beyond this point can lead to issues such as overheating, reduced battery life, and potentially safety hazards.

 

Heat Generation

As you charge your electric vehicle, heat is generated in the battery cells. As the battery approaches full capacity, the heat generated increases. This added heat can cause a variety of issues, including a reduced lifespan for your battery. By charging at a slower rate during the final 20%, you can help keep those temperatures in check.

What are the benefits of charging your EV to the 80% Sweet Spot?

EV Type 2 Charger Plug

Battery Longevity
Charging a lithium-ion battery to its maximum capacity regularly can accelerate its aging process. To promote longer battery life, EV manufacturers often implement charging algorithms that prioritise slower charging in the upper state of charge range. This is part of the trade-off between achieving a quick charge and preserving the battery’s health over the long term.


Balancing Cells
Lithium-ion batteries consist of multiple cells, and during charging, these cells may not charge uniformly. Balancing ensures that each cell reaches its full capacity without overcharging or stressing any individual cell. This balancing process becomes more critical as the battery approaches full capacity, contributing to the slower charging rate.


User Safety
Slowing down the charging rate in the upper range also helps ensure user safety. Rapid charging at high states of charge could potentially lead to overcharging or overheating, presenting safety risks. By implementing controlled charging rates, manufacturers prioritise user safety in the charging process.

Adapting charging to longer trips and EV storage

While the 80% battery range or as we like to call it the Sweet Spot, is ideal for daily use, there are exceptions. If you’re planning a long road trip, charging your EV to a higher level for the journey is OK.

 

Head to your nearest super charging station and follow the navigation system provided by your EV manufacturer. For extended periods of storage, the recommended charge level is around 50%. This helps balance the need for maintaining some charge without putting unnecessary stress on the battery during idle periods.

 

Staying in the Sweet Spot

While you might be tempted to go for gold and try to charge up to 100% every time you see a super charging station – just don’t!


The recommended 80% EV battery charge strikes a balance between providing enough driving range for most daily activities and minimizing stress on the battery.


Charging within this 80% capacity Sweet Spot will preserve the health of your electric vehicle’s battery health, and ultimately translate to cost savings and allow us to enjoy the smooth and sustainable driving experience for longer.

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