Model 3

Charging cycles question

edited November -1 in Model 3
AS I was avidly talking to a colleague about how wonderful my M3 is, he asked "Yes, but how long will the battery last?" I said it is expected to last hundreds of thousands of miles. He said that was not possible because lithium ion batteries have a limited number of charging cycles. I am not a battery maven. What is the science behind why Tesla's batteries last so long?


  • edited June 2019
    You are right. Take the bet.

    Best well explained to laymen explanation is here.

    Basics are Li-ion batteries have 500 full charge and discharge cycles. A 240 mile range Telsa that would be 120,000 miles. But that's a brutal charging schedule and no one does that in normal usage. It's not linear but if you were to drive 120 miles a day and charge to 120 a day, that would be 240,000 miles. That's still an extreme example, close to my situation actually but not most people's.

    So practically, probably as long as gasoline engine with the same caveats that well cared it will last longer.

    You have to toss degradation in there also. The battery will keep losing ability to store charge If you get a cool app called StatsApp for Tesla, it has a graphic on "Battery Health" it has a graphic on degradation which begins day one of usage.
  • edited November -1
    One thing that Tesla does, or did in the past, is build the battery packs with more physical capacity than reported by the system. Some cars got a 5% range increase via a firmware update. I have a LR AWD so I didn't get a range increase but I got a 5% power increase. Overnight a new LR RWD range went from 310 mi to 324.

    The management system could be tapping that "reserve" capacity as the battery ages too.
    edited June 2019
    Lithium ion battery is also a very generic term. Have you ever bought cheap batteries from China versus the original battery in a device? Battery science is incredibly complex and Tesla is far ahead of the rest. While your mileage may vary slightly, 500,000 is a good guess before your battery will be down to the range of a new ipace or etron, not great, but even at that mileage better than the big boys offer now new.
  • edited June 2019
    The Model 3’s battery pack is well engineered (just as such with the model x/s). The model 3 will last well past 500,000 miles. At that point, I would have to guess 60% of original battery.
  • edited June 2019
    Your colleague is correct about the batteries having a limited number of charging cycles, but at the same time draws an incorrect conclusion from that fact. If the limit were 15 trillion cycles, the batteries would last far, far longer than the hundreds of thousands of miles you mentioned.

    This simple fact proves your colleague's statement can never be correct.

    Let's look at this from a practical viewpoint. I bought a Tesla last year. Let's say I drive the car ~ 18000 miles per year. Using a 300 mile cycle, I will drive 360,000 miles and use up about 1200 cycles in 20 years.

    A typical lithium ion battery (think about your phone perhaps) are currently projected to be capable of 400-1200 lifetime cycles, per a Wikipedia article I just looked at. Tesla batteries are at least on the long side of that estimate, which would support the 360k mile description above.

    However, in real world performance, the Model 3 battery has not yet demonstrated lifetime performance, since the lifetimes are just beginning. Tesla battery tech performance data available shows no greater than 10% performance degradation after 160k miles, and Model 3 battery tech is significantly advanced when compared to the battery tech that has achieved that result.

    Your colleague, it turns out, has a few more problems in his argument that just drawing the wrong conclusions from simple facts.....
  • edited June 2019
    Elon’s tweet back in April.

    Model 3 drive unit & body is designed like a commercial truck for a million mile life. Current battery modules should last 300k to 500k miles (1500 cycles). Replacing modules (not pack) will only cost $5k to $7k
  • edited November -1
    If after 500,000 miles I need to spend $5k-$7k on maintenance.

    I'll be more than happy to pay it.
  • edited November -1
    A little knowledge is a dangerous thing. Your friend exemplifies this ditty.
  • edited June 2019
    There is historical data and there is worst case scenario. Historical data is based on the S and X which have a different system than the Model 3. Those have performed exceptionally. Worst case is going to be what the warranty which is 70% at 100,000 miles unless you have the LR. Hope for the best and plan for the worst.
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