Why you might only charge your battery to 80%

030 Jan 2024

Stick to a maximum battery charge of 80% and you can expect these three main benefits  

When it comes to charging your EV, aiming for an 80% maximum charge is better practise than charging all the way to 100%. This might not make much sense if you’re new to the EV world, especially if you’re used to charging things to 100%, like mobiles or laptops. 

At bp pulse, we’re here to help turn EV theory into everyday language for better charging experiences. In this article, we’ll explain why that guideline is handy to remember, and the three benefits you could get from an 80% charge. 

1. It can make your battery (and bank balance) healthier 

Here’s a bit of helpful science. Most batteries in EVs – and our mobile phones and laptops too - are Lithium-ion, because they’re light and recharge well. However, being charged repeatedly, discharging power, then being charged again – what is called the charging cycle – may eventually cause them to degrade. No batteries last for ever, of course, but staying proactive and aiming for 80% charge can help them last longer. This is because the battery finds it easier to charge when it is slightly empty, rather than nearly full, and therefore has less stress within its charging cycle.

2. It may look after your braking system

You might remember from school that energy cannot be destroyed, it can only be converted. In other words, energy always goes somewhere. Most EVS have turned that to their advantage by having regenerative braking systems. This converts the kinetic energy caused when you brake into stored energy in your battery. Now, if you allow your battery to remain a little empty at 80%, it has the space to take in this energy from braking. Depending on your make and model, this may improve the overall efficiency of your EV and could extend the lifespan of your braking system too.

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3. It could help speed up your charging

The charging speed of a battery is not the same throughout – it varies at the beginning and end. (This is called the charging curve, and you can find out more about it in this guide.) As a battery reaches its maximum capacity of 100%, its charging speed slows down, because the electrons coming in have to work harder to find space. If you stop at 80%, you’re avoiding the slowest rate of charge right at the end. Think of it as quitting while you’re ahead – by stopping the charging before it slows down, it’s more likely that you’re charging in the fastest speed possible for your battery.

4. You may be able to set an 80% limit for your charging

Many EVs now give you the option of setting maximum charge, which can mean you won’t accidentally go over, depending on its settings. Your vehicle manual or manufacturer should be able to tell you if you’ve got this feature.

5. But if you need to charge to 100%, it’s ok

There may be a time when you'd rather charge to full, for example if you have a long distance to cover between charging and you’re not sure of the range. Just think of this as the exception, and not the rule, and bear in mind that doing this repeatedly may affect your battery life and performance, depending on your EV.

At bp pulse, we’re here to help you charge, while fully recharging yourself. With many of our chargers close to handy places to grab a bite or drink, your charging can be as helpful and enjoyable as possible.

Find a charging point near you

Download the bp pulse app to see where you’ll find us and subscribe to save your favourite charging sites and access our lowest charging rates.

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