How Long Do Electric Car Batteries Last Before Replacement? Not What You Thought

Post date: 19-Apr-2020 10:14:47

Two of the most frequently asked questions I get about EVs are also the most difficult to answer what is the battery life expectancy in a modern TV and should I buy a used one is it okay to buy a used one the reason these questions are so difficult to answer is because we simply don't have enough real world information at this point to really know how these batteries will behave long-term there's been a significant improvement in battery technology.

Just in the last few years alone and that really means that these latest group of vehicles are likely to last a little bit longer than the ones back in 2012 there are a variety of factors that play into battery life expectancy the state of charge of the battery how long it's at a high state of charge or at a low state of charge so batteries in general will degrade faster if they're capped at a hundred percent were kept at 0% they'll also degrade faster if they're kept at high temperatures.

At a 100 percent state of charge if they're discharged rapidly if they're charged rapidly if they're hot when they're charged hot when they're discharged etc that means that looking at this critically an Eevee that was driven by someone in a very moderate climate say coastal California coastal Oregon coastal Washington that had a relatively short commute and never really charged their battery completely always used their home charger it's probably going to have a better battery life than someone in Arizona that always exceeds the recommended range of their vehicle.

Drives it near to zero then DC fast charges it at either end of their daily cycle a good anecdote of this is a friend of mine that lives in Phoenix Arizona he bought one of the very first Leafs that came out back in 2012 with a DC fast charging he was charging it at work charging at home on either end of his commute obviously with the air-conditioning blasting at 110 115 degree heat in Phoenix for a while he had absolutely no problem with his leaf then he started needing to drive around more during the day and started using those DC fast charged Asians so we started DC fast charging it multiple times a day again in that high heat driving the battery to near zero filling it to near complete.

Each time after he hit about twenty thousand miles he noticed that he was no longer able to go from home to work in a complete charge so he started stopping halfway in between and DC fast charging the battery then he couldn't make it all the way home and had to do the same thing after about 30 to 40 thousand miles he noticed that he had only about 25 to 30 miles of range in his leaf depending on how he drove it obviously upset he called me about this problem I listened to him described it and I said well knowing what I know about batteries that sounds completely normal to me because you're doing all the things that you shouldn't do for extended battery life in a vehicle.

The reality of that is that battery electric vehicles are not good vehicles for every use case scenario if you have that kind of use case then maybe a battery electric vehicle isn't the right vehicle for you or actually maybe you need a battery electric vehicle with a bigger battery the reason I say that is because complete charge and discharge cycles and fast charging at high temperatures are bad for batteries so for instance if he had had a Tesla Model S he likely would not have noticed as much of a problem.

In that same use case because with the much longer range you're not using 100% of the battery and you're not going from zero to 100% every day all the time now in that same use case scenario the Tesla Model S would have received some battery degradation as well it just wouldn't have been as noticeable in his use case the problem was he started with a vehicle that was only barely capable of handling his daily commute now I mentioned Phoenix and DC fast charging DC fast charging your vehicle will lower the battery life expectancy of the battery pack however it's actually shorter than we initially thought Idaho National Laboratories did a test in Phoenix with a group of Nissan Leafs.

They only charged one group on level two and they only charged the other group with DC fast charged a shion's it did result in a drop but it was only about two to three percent lifetime over 40,000 miles the bigger take away from that test however was that Idaho National Laboratories noted a 25 percent drop in battery life over 40,000 miles now why that loss occurred can be seen as a variety of different factors first off the test was being done in Phoenix which is very hot as well.

It was also done with a first-generation Nissan Leaf and that first generation leaf had slightly older battery technology than we see in the latest group of EVs that Nissan Leaf also doesn't have an actively cooled battery pack which does seem to affect battery life and the last thing of course is that entire group of Leafs were charged all the way to 100% every time to combat this issue many modern EVs are only using a portion of their battery so say for instance you buy a vehicle that says it has a 24 kilowatt hour battery it may only use 20 to 22 kilowatts of the battery.

That's done so that the battery is never fully charged or fully discharged it helps reduce the cycling of the battery cooling of the battery also plays into battery life but exactly how much we're not quite sure yet manufacturers have taken two different approaches to this problem General Motors Fiat and Tesla are liquid cooling their batteries so the batteries actually have liquid cooling elements in them they have a radiator up front a coolant pump and that is actively cooling the battery.

Then in general should do a better job of cooling the battery then air cooling a battery like we see in the Volkswagen the Nissan or some of those other products out there however as I said at this point in time it's impossible to tell what that difference really is to help combat this most evie manufacturers at this point offers some sort of capacity warranty while the loss of 25 percent capacity over 40,000 miles sounds really scary it's not that far outside the norm.

Most vehicle manufacturers tell me that you should expect about 30% over eight years or a hundred thousand miles and that's right where most vehicle manufacturers have set their warranties on the batteries initially there were no capacity warranties but now most manufacturers are saying that after eight years and a hundred thousand miles you should get about 70 percent of your original battery capacity an important consideration is that the vehicles like this eGolf that do have a capacity warranty.

The warranties all say that if you drop below that threshold within that time frame the manufacturer will repair the battery pack or replace it with a battery pack that just brings you right up to that 70% or whatever percent the manufacturer is warranting for you will not get a 100 percent good battery out of them if you drop below that threshold so say for instance at your 7 this battery days to say 65 percent capacity and Volkswagen says well that is qualified under the warranty so we will repair or replace your battery pack you're only going to get right up to about that 70 percent appropriate evening selection is absolutely essential if you're truly concerned about battery life and battery range because making sure the vehicle fits in your use case will not only help you extend your battery life it will also help make it still fit in your life even if the battery does wear overtime the biggest thing when it comes to battery life as well as range is setting appropriate expectations and keeping them in mind when something does go wrong.