Plug In America Tests Older Tesla Roadsters, Finds Battery Durability Better Than Promised

TTAC Staff
by TTAC Staff

Tesla Roadster battery pack – Tesla Photo

One drawback to cars that run on batteries is that over time and multiple charge/discharge cycles, batteries will lose capacity. Individual cells start to fail to meet specifications and when enough cells go bad, it’s time for another battery pack. Since capacity is directly related to range and since battery packs are expensive to replace, how quickly batteries deteriorate is an important factor in the overall cost and practicality of EVs.

When Tesla first announced their Roadster EV in 2006, the company said that due the company’s proprietary battery management system and design of their lithium-iom battery packs, would ensure that after five years or 50,000 miles, the Roadster’s battery pack would still have 70 percent of it’s rated capacity when new, 53 kWh, enough electrons for a 244 mile range ( 2006 statement on battery age by Tesla founder Martin Eberhard here). The Tesla Roadster went on sale in 2008, which means there are now roadsters that have been on the road for as long as five years, and I’m sure many that have reached or exceeded 50,000 miles of use. It’s now possible to test Tesla’s claims regarding battery durability. A standard from the laptop industry is that lithium-ion battery packs are still serviceable above 80% capacity.

The independent EV advocacy group, Plug In America (PIA) decided to do just that and their chief science officer, Tom Saxton has reported the results of an owner-reported survey of Tesla battery packs, based on a sample size of 4% of all 2,500 Roadsters made. Plug In America discovered that the Tesla battery packs are performing much better than advertised. After 100,000 miles, double the advertised 70% capacity life, the battery packs have an average capacity of 80-85%.

PIA also tested for climate differences because PIA’s earlier first ever survey of EV battery life involving owners of Nissan Leafs showed measurable declines in battery capacity in hot climates. The Leaf has a much simpler battery heat management system than used by Tesla. A surveys of first generation Toyota RAV4 EV owners, which was on sale from 1997 to 2003, in order to measure performance in batteries at least 10 years old, is also underway, as is a survey of Tesla Model S owners but it’s too early for any real meaningful data to be obtained on that car.

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  • JD321 JD321 on Jul 17, 2013

    Honda has a great lease deal on their Fit EV so if you are self-limiting to a 35 miles radius, then this is the EV you you! You don't have to own an expensive battery pack and they install a home charger for free.

  • BobSmith BobSmith on Jul 29, 2014

    The ICE has been built and refined in large numbers for over 100 years. The BEV only has about 10 years of reasonably small production. Tesla model S with 250+ miles of range certainly makes a great day car. Most people could live with it. There are already battery advances on the horizon that will increase capacity, decrease cost and increase durability. With a battery that had a 500 mile range, lower cost and 10,000 cycle life - the ICE will look like expensive old technology.

  • CanadaCraig You can just imagine how quickly the tires are going to wear out on a 5,800 lbs AWD 2024 Dodge Charger.
  • Luke42 I tried FSD for a month in December 2022 on my Model Y and wasn’t impressed.The building-blocks were amazing but sum of the all of those amazing parts was about as useful as Honda Sensing in terms of reducing the driver’s workload.I have a list of fixes I need to see in Autopilot before I blow another $200 renting FSD. But I will try it for free for a month.I would love it if FSD v12 lived up to the hype and my mind were changed. But I have no reason to believe I might be wrong at this point, based on the reviews I’ve read so far. [shrug]. I’m sure I’ll have more to say about it once I get to test it.
  • FormerFF We bought three new and one used car last year, so we won't be visiting any showrooms this year unless a meteor hits one of them. Sorry to hear that Mini has terminated the manual transmission, a Mini could be a fun car to drive with a stick.It appears that 2025 is going to see a significant decrease in the number of models that can be had with a stick. The used car we bought is a Mk 7 GTI with a six speed manual, and my younger daughter and I are enjoying it quite a lot. We'll be hanging on to it for many years.
  • Oberkanone Where is the value here? Magna is assembling the vehicles. The IP is not novel. Just buy the IP at bankruptcy stage for next to nothing.
  • Jalop1991 what, no Turbo trim?
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