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Question: battery replacement price-performance?

Discussion in 'Generation 1 Prius Discussion' started by bwilson4web, Jul 9, 2010.

  1. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Looking at the recent 'hot weather' associated, traction battery problem reports, I began to wonder about the financing aspects of replacing a battery. Patrick Wong could probably solve this in seconds but I'm more of a cash accounting guy. So what sort of model works?

    ASSUMPTIONS

    • No other known problems, just a failed battery
    • Assume $2,000 total including installation
      • $1,700 Re-InVolt, independent labor, $250
    • Expected life: 10 years
    • Annual mileage: 15,000 (EPA estimate for annual fuel costs)
    • 8% interest, car as collateral (possible? reasonable?)
    RATIONALIZATION - ANALYSIS

    How many can buy a 50 MPG, five seat, sedan replacement for $2,000? To me, the traction battery is a lower cost version of the original car.

    Compared to a 35 MPG car (assuming one can be had for $2,000,) the annual savings at today's gas prices should run about $400/year.

    An 18 month, $2,000 loan at 8% would run $118.28/mo. with $2,129.05 total cost (used Bankrate.com.)

    So to my way of thinking, $212/year cost over 10 years versus $400/year fuel savings . . . after five years, we're makin' money again.

    These are just 'back of the envelope' and ignored the risks of other failures such as inverter, transaxle or steering.

    Thoughts?

    Bob Wilson
     
    #1 bwilson4web, Jul 9, 2010
  2. richard schumacher

    richard schumacher shortbus driver

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    Your first point is more than enough all by itself. It's impossible to buy a 50 MPG car for $3K.

    Borrowing money to replace the battery adds unfortunately to the cost. The ugly truth is that anyone who owns a car really ought to keep $1K or more in the bank to cover major repairs. Note that this is *not* an argument in favor of buying an extended warranty.
     
    #2 richard schumacher, Jul 9, 2010
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  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Bob,

    Well, I would question your assumption that you can safely ignore the risk of other failures such as the inverter, transaxle and electric steering gear. If you were talking about a Toyota Corolla then I would say the risk of another expensive failure might be low, and aftermarket alternatives are abundant.

    If you are talking about your own vehicle, we know that your struts and shocks are overdue to be replaced and that would probably cost $2K if you visited your friendly local Toyota dealer. If you DIY it might cost you $500 or so for the needed parts.

    With an old Prius I would say the risk of another failure is "high". To me "high" means 25% chance or more of another "expensive" failure, as the car moves from 100K to 150K miles. If you can DIY then no worries but if you are paying dealer rates, forget it.

    A popular retort of Prius owners when confronted with the likelihood of replacing the traction battery is to say that this doesn't cost more than replacing the transaxle on a regular car, so what's the big deal.

    I've always had trouble with that answer, because the implicit assumption is that the Prius transaxle is bulletproof and will never need to be replaced. We know this is untrue with Classic, and it remains to be seen what the 2G failure rate will be. Certainly the repair price associated with a Prius transaxle is going to be much higher than a conventional vehicle unless you install a salvage unit.
     
    #3 Patrick Wong, Jul 9, 2010
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Any NHW11. My particular NHW11 is likely to have an atypical service life because my early studies revealed 'knees' in the performance data such as 65 mph maximum cruise speed and 55 mph hill climb speed. I tend to stay on the easy side of the performance curves.
    Ok, assuming 15k miles per year, the EPA miles uses to calculate annual fuel costs, this suggests:

    • (150-100)/15 ~= 3.3 yrs, 25% chance of major failure
    This seems a little high, ~8%/year compared to the USA fleet salvage rate of ~3%/year (from a salvage industry report.) Such a high rate should be noticable yet Consumer Reports still shows our NHW11 as being relatively reliable. But it poses an interesting study:
    Review the history of postings to gather model years, miles and NHW11 failures. Then see if the failure reports reveal usable patterns.
    ​
    I'm just speculating about an approach we can use to improve our estimates of major failure rates.

    Bob Wilson
     
    #4 bwilson4web, Jul 10, 2010
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