Login
What is the 80/20 Rule and How Can I Get the Most Out of my EV's Battery?
If you’re an EV driver or planning on becoming one in the near future, you may have have heard about the ’80/20′ or ‘80%’ rule. But what is it and how can it help your EV’s battery performance?
EV batteries, just like all batteries, don’t really like to be charged to 100%. When a battery is consistently charged to 100% you will notice a loss of capacity over an extended period of time. An everyday example is iPhone batteries which you probably would have noticed hold a lot less charge than when you bought it brand new.
This is in down part to leaving your phone on charge as you sleep, as it will continue to ‘charge’ even when the battery reaches 100%. Fortunately with EV’s, there is technology in both the vehicles battery and the EV Charger that prevent charging continuing past 100%.
The 80/20 Rule
This rule in simple terms means that EV drivers should keep their battery charged to between 20 – 80% whenever possible. When a battery reaches capacity it’s overall lifespan reduces as it is it put under an increased amount of strain.
Batteries should be kept above 20% firstly to maintain the batteries health, but also to keep as a back up to reduce range anxiety. We know the UK’s charging network isn’t perfect, so it’s a good habit to get into to charge once your EV reaches 20% instead of near empty.
As a side note, it is strongly encouraged to never leave an EV at below 20% charge for an extended period. Energy will discharge from the battery over time, leaving it low puts the EV at risk of reaching dangerously low levels of charge or even running out completely.
This shouldn’t be thought about as a rule specific to an EV’s battery however. For example, you wouldn’t consistently use 100% of your brakes capacity, or always floor your accelerator every time you come out of a corner. Excessive use will always lead to additional wear and tear so it is best to always keep all parts of your EV working well within their capacity.
How Does EV Charging Work?
Charging your EV doesn’t follow a linear pattern, as charge speed depends of a range of variables, most importantly the current level of charge. For some EV’s, it can take as long to charge the first 80% of the battery as the final 20%.
The easiest example online to understand why this happens, is to think of a theatre. For the first people entering the theatre it is quick to find your seat and sit down. However after 80% capacity is reached, it takes the final 20% much longer as they have to move past those already sat down in their way. In this analogy swap the audience for electrons and the theatre for the batteries capacity and it starts to make sense.
It is because of this process that it is considered both more efficient – and good etiquette, to only ever charge to 80% when using public EV Charge Points. In the extra time it takes to top up the final 20%, you could be over 50 miles down the road, where you could charge at a faster rate.
So, How do I Keep my Battery Healthy?
Minimise Time Spent with 100% Charge – Use the smart technology in your EV or Home EV Charger to keep the battery charged to 80% max. For occasional trips where 100% charge is required, then there would be no noticeable long term effects.
Home Charging – It is best to charge your EV with slower ‘fast’ Home EV Chargers for the majority of the time. Fast charging is okay occasionally, but studies show that EV’s charged continuously using rapid chargers lose 10% performance over 8 years.
Avoid Extreme Temperatures – Batteries also don’t like extreme weather, so driving should be limited in these scenarios – especially during heatwaves as this comes with a heightened risk of overheating which would cause long-term battery damage.
As mentioned above, charging with Home EV Chargers instead of relying on rapid public EV Charge Points, will do you battery good in the long run. If you are thinking of having a Home EV Charger installed, click the link below to see how our fantastic range of EV Chargers – all available on 0% Finance!