What is the Electric Vehicle 80% Rule? | EV Basics

In this video we tackle the "80 Percent Rule." What is it? Well, most of the time you should only charge an EV to 80%. Why is that though? We'll explain how reducing your charge can maintain the overall health of your battery and be a much more efficient strategy for tackling road trips in an electric car.

🔌 Check out our recommendations for the best home EV chargers:

0:00 Introduction
0:32 Two Reasons Why You Should Limit Your Charge
1:45 Charging Curves
3:05 Charging on Road Trips
4:09 When to Charge to 100%
4:58 How to Charge EVs Wirelessly
5:50 Maintaining Battery Health
6:52 Automatic Limiting of Charging
8:05 Conclusions

EV Pulse has all the information you need to master Electric Vehicles! How do you reduce range anxiety? Should you keep your car constantly charged? All of those questions and more are ones we want to help you answer, so you can be an expert when it comes to EVs.

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[bigdougscommentary]

I had a 2013 Nissan Leaf that I charged overnight to 100% everyday because I needed the range for my wife’s commute. Now the Leafs were notorious for battery degradation. BUT, I had 80% capacity when I sold the Leaf with 80K after 6 years of use. I also frequently charged using the CHADEMO fast charging port when I used the Leaf for Uber driving. This is REAL WORLD experience not theoretical musings. However, I do agree that charging to 100% wastes time.

[macbuff]

Another great analogy which I learned in high school physics class was filling up a glass or bottle of with water at the tap. The closer you get to the bottom, the slower you have to add the water otherwise the air bubbles trapped in the water will pile up and push water out.

The increasing voltage in the battery creates a similar sort of "resistance" to charging which is also why KIA moved to 800 Volt charging technology.

[johannjohann]

Thank you for the video. I wonder how many people buying an EV car are told this when they buy it. BUT and it's a BIG BUT, if you are only supposed to charge your EV battery to 80% AND you are ONLY supposed to let the battery get to 20% before charging that means you are ONLY running on a 60% charge! So, if an advertised range of an EV is 300 miles, in reality it is only 180 miles!

[irfanhusein]

I’m been charging my Mach E to 90% at home since I got It. I’ve occasionally charged to 100% before road tripping, but only to 80% on D/C fast chargers. Now with over 34000 miles on the odometer, I’ve experienced no loss of battery capacity at all.

[BuckRogers]

Thank you. I would have included a 20% discharge limit too. You may exacerbate range anxiety but at a great service to your viewers.

[windowman]

Great video. I have my first Ev preordered now. It’s killing me waiting… so as I drive around in my dinosaur 2020 Gmc Sierra I like to educate myself on what’s to come. Thx again for the video. I can’t wait for my Silverado Ev rst

[johnkeen]

Also, when you charge to 100% . You get no re-gen until the battery charge drops to 80-90%;..

[anthonydeloach]

This guy is very good. Thanks for the 80% information. I am wondering if charging at low voltages also preserves the battery a little more.

[JasonTaylor-poxc]

The 80% rule is mostly to help with battery longevity but mainly for batteries with significant amounts of nickel in them (NCA and MNC). However, a somewhat newer chemistry (LFP) uses iron instead of nickel. This does three things - lowers the overall energy density, significantly lowers the fire hazard and removes the 80% rule for battery health. Because of the lower energy density, the same size battery will have a shorter range but you get that back by being able to charge to 100% on a daily basis.

As pointed out, the closer to 100% you get, regardless of the chemistry, the slower the charging becomes to the point that last 20% takes longer than the first 80%. For my car, I charge to 90% on a daily basis (home charging).

[dividdbyZero]

I charge my Bolt to 70% (Level 2) Usually from around 35-45%. Gives me plenty of range. I could easily do with less range, but I feel my current method is better for battery life. I only charge at home (so far), and I only need to charge 2-3 times a week.

[FalkinerTim]

I have an MG ZS EV Mk1 and the manual advises charging to 100% occasionally to balance the batteries. As far as I can see from the web chit chat, owners of the MGs who home charge their cars cannot find any battery degradation. Most of the time I just bounce between 55% and 80% using solar.

[trenier]

I heard the 80% rule years ago. I've done it with cell phones, laptops and tablets. I own a Chevy Bolt EUV and I charge it at home at 120 volts and up to 80% like my other electric devices. Time will tell. Nice video.

[brianmurray]

Good video. I figured I check this out while charging my 2021 hyundai kona. Went to charge from 30% to 80% on a DC fast, time nearly doubled if I were to go the extra 10%.

[petesig]

I am doing 40% ---> 70% now for routine driving and charging. I reckon I won't need to top it up from the home-charger much more often than twice per week, and only save the 100% for long country road trips 👌😃

[georgepelton]

When to charge to 100%? I charge at home or at hotels to 100% before starting a road trip. However, helping battery life by stoping 90% may make more sense if you don't need to shorten your first charge stop. Usually the car is ready before I am, so my 100% charge is unnecessary.

If I had a car with an LFP battery, I would charge to 100% once per week, and always charge to 100% before road trips.

[claytonburke]

Traditional lead acid batteries in gasoline & deisel vehicles work the same way at obviously lower voltages. A dead flat 12 volt battery will start charging at around 20 amps then as voltage increases the rate of charge slows to 2 amps and eventually charging will stop when battery is fully charged

[roamingbeemer]

I believe manufactures vary in how much buffer the HV battery has in the top and bottom end. Bigger warranty may mean a bigger buffer. So 100% may not mean 100%.

[Inventors_Toolbox]

So here's my info. I'm an electronics tech and I've been an EV driver around the last 20 years or so. My current vehicle is my 4th ev. It's a 2012 nissan leaf with over 80, 000 miles on it. Purchased it used from the dealer with 5, 000 miles on it. It was a demo model, showed hard use, tires and brakes almost shot even with only 5k miles. I do an 80% charge spring through fall, 100% charge in winter due to nissan PPD. My current battery capacity is about 8 of 12 bars according to the leafs guesstimater. Puts the vehicle somewhere around 60% of original battery life. I'll probably get another 2-4 years out before my range to work requirements make a battery swap is unavoidable. Although I may just drop the battery compartment and do a conversion to LiFePO4 batteries, lower initial capacity but more stable an longer overall life. Also DIY battery gives me the opportunity to add thermal battery management. Most used leafs with the same age and mileage as mine that I have seen have around 4 battery bars (30%) life left although this is just my anecdotal experience

[michaelgarvin]

Great video Carig! You're still funny as ever 🤣

[Jeddin]

A lithium ion battery is happiest at 50% when there is perfect equilibrium of ion charges between the positive and negative terminals and the least likelihood of electroplating which will permanently remove ions from circulation and thus degrade the battery. This is a chemical reaction and is a function of both heat and time. Up to 60% charge there is virtually no time based degradation. Up to 80% the amount of degradation is fairly minimal and that has been adopted by most batteries as a good compromise between function and degradation. Having said that 70% is better then 80% and 60% is better still. If you don’t need the full range as I don’t then it’s best to keep your charging in 40-60% band