tokenride said:
Companies dont want to over warranty batteries since they will degrade no matter what.
I'm not sure if I necessarily agree with this statement. It should be possible to build a fairly robust battery, which would last a decade or longer without experiencing unacceptable degradation levels. We already had batteries that would meet this design goal in the previous generation of EVs, which were on the road around the millennium. Some of the 1st gen RAV4 EV drivers are still getting nearly full utility our of their EVs a decade and many miles later. The particular problem we face is that the previous generation of batteries (NiMH) cannot be used in EVs due to a patent held by Chevron. These batteries were also heavier and less energy dense, which makes them less desirable given the recent advances in battery technology. Also, some of the raw materials, especially the heavy metals, are not desirable due to their toxicity and relatively high prices.
The Prius, which is a hybrid and not an EV, is allowed to continue use this technology. When you look at the battery Toyota was recently using, it weighs around 100 lbs and provides a little more than 1 kWh of capacity. If you took this exact same technology and scaled it to the capacity level the LEAF is using, the battery would literally weigh a ton. The lithium-ion batteries in the new generation of EVs are more advanced and desirable, but also less proven. The first automaker to put them into larger-scale use was Tesla with their Roadster, I believe. Generally speaking, this means that these cars have been on the road less than 5 years. It's probably fair to say that the technology is not fully proven and field tested yet. As an aside, Tesla used a robust active cooling system to mitigate some of the risks they assumed by pursuing some of these design decision.
A warranty arrangement usually gives the manufacturer an additional incentive to come up with better and more robust systems and designs. The consumers on the other hand has some assurance that they will get a certain minimum level of utility of out the car they purchased. This arrangement is not ideal, obviously, but it has been shown to work reasonably well. I think it's encouraging to see that other EV manufactures seem to be offering a capacity warranty with their new products this year as a matter of fact. In that sense, however painful the experience might have been for some, early LEAF drivers might have their place in EV history.
The other alternative is not to sell the battery, but lease it instead. The ownership stays with the manufacturer in this case, and they sell a service with an associated performance guarantee. In a way, it's like an unlimited warranty, but you have to pay for it. Not dissimilar to the battery swap scheme you suggested above. Although the perpetual rental option was not popular with owners on MNL, the EV industry might try to move in this direction. Car buyers in Europe are typically already offered the option of either buying or leasing the battery when they get a new vehicle.
(I apologize for the verbosity of this post, and for stating the obvious, but I felt we had to find some common ground.)