Tesla Batteries Retain Over 90 Percent Charging Power After 160,000 Miles, Survey Finds (engadget.com)

According to a survey of over 350 Tesla owners, Tesla batteries retain over 90 percent of their charging power after 160,000 miles. The EVs dropped only 5 percent of their capacity after 50,000 miles, but lose it at a much slower rate after that. Most Tesla vehicles will have over 90 percent of their charging power after around 185,000 miles, and 80 percent capacity after 500,000. Engadget reports: Tesla has no battery degradation warranty on its Model S and X luxury EVs, but guarantees that the Model 3 will retain 70 percent battery capacity after 120,000 miles (long-range battery) and 100,000 miles (shorter-range battery). That's a bit more generous than the one Nissan offers on the Leaf (66 percent over 100,000 miles) for instance. According to the survey data, Tesla will easily be able to meet this mark.

Comments

Re:Too expensive

[Mr D from 63]

This 'survery' was basically a collection of message board posts. 350 respondents, but the article doesn't say how respondents reported results with so many miles. I looked at the first few pages of respondents and none reported having driven near 100K miles yet. So I assume the actual sample of high mileage owners was quite small. Too bad the author neglected that obviously important info.

OK, here is the actual data if anyone is interested;

https://docs.google.com/spread...

Re:Tesla Batteries

[Rei]

Indeed. A few other things:

  * For a vehicle with a range of, say, 250 miles, where the driver drives, say, 25 miles per day, is only using 1/10th of a cycle per day.
  * Few owners charge to 100% daily. Most set a limit in the 60-90% range, with 70% and 80% being common. So not only are they doing shallow cycles, but they're doing shallow cycles in a near-optimal-for-longevity portion of the pack.
  * Unlike laptop batteries, which are often just cells in series and thus limited by the weakest cell, Tesla packs have many dozen cells in parallel forming bricks, which are then linked in series (these in turn are linked in parallel). A failure in an individual cell has an insignificant impact on the whole.

In short, you have shallow cycles, in a gentle portion of the charge curve, with a chemistry specifically designed for long life, a failure-resistant architecture, and climate controlled to optimal operating conditions. You get what you design for. A cell phone and a laptop, by contrast, design for low unit cost and high energy density. Tesla packs are only 150-180Wh/kg, whereas you might get over 240Wh/kg in a cell phone battery. But cell phones and laptops are only designing for a couple year lifespan, with deeper cycles every day, no redundancy, no climate control, etc

Re:Too expensive

[dgatwood]

Those use pretty much the same kind of batteries, donâ(TM)t they? You might not get 500k miles out of them on a bike, but in terms of capacity after x charge/discharge cycles they might well be similar.

I doubt you would even get close, realistically, for two reasons:

• Tesla vehicles use a heat pump to keep the battery within a narrow operating temperature range to minimize battery degradation during both regenerative braking and normal charging.
• Tesla vehicles contain additional pack balancing circuitry to ensure that each cell gets charged as much as possible even if it is surrounded by weaker cells, and to ensure that cells can discharge as much as possible before the pack fails.

A bicycle is not likely to do either of those things. It probably isn't even physically possible to usefully put a heat pump into something the size of a bicycle—a motorcycle, maybe, but not a bicycle.

Re:How are their batteries so much better than lap

[Rei]

1) Laptop batteries are designed for energy density, not longevity. There are tradeoffs in chemistry selection.
2) They're not climate controlled. Just the opposite, they're right next to a source of heat.
3) They go through deeper cycles, over a wider portion of the SoC range.
4) They have no redundancy / cell bypass
5) They're designed for a product with a pre-determined expected lifespan of only a few years, so they have no incentive to do better.

You can design to any spec, if you're willing to accept the tradeoffs.