GM-Volt.com has an interview with the CEO of Compact Power (the cell provider for the Volt battery), in which he reveals the price per kWh for the battery (not including all the electronics).
The price quoted is $350/kWh. This means the Volt’s battery is $5,600 for the battery cells only. All the electronics, battery casing, cooling/heating, etc, are extra and on top of that figure. The $8,000 estimate for the entire battery pack seems to be plausible, if not right on the money. At the finished pack level, this is a cost of $1,000 per usable kWh. Its hopeful the usable kWh price for electric vehicles reaches $500 by 2015 and $250 by 2020. These price targets would be achieved through a combination of increased cycle life and depth of discharge, as well as advanced manufacturing technologies that decrease the time it takes to build a cell, module and pack and allow for higher throughput.
This doesn’t immediately impact the Volt’s MSRP however, because there is still the unknown of battery life. I did see a chart in a presentation (pg. 27) from MIT that depicted depth of discharge versus cycle life – while it was for NiMH and not Li-Ion, it is known that Li-Ion exhibits a similar pattern. It showed the number of cycles increasing logarithmically with depth of discharge; to 75% original capacity, it was about 1,000 cycles for 100% DoD, about 1,600 cycles for 80% DoD, and 2,750 cycles for 50% DoD. You can see that the increase is not linear – you get a 60% boost by reducing DoD from 100% to 80%, and a 175% boost from reducing DoD form 100% to 50%. The issue with automotive batteries is how they’ll be affected by temperature and how that impacts their cycle life.
The Volt would need about 3,800 cycles to 75% to meet its targets based on what GM has said up to this point. The goal appears to get to the 10 year/150,000 mile mark with 75% degradation in the battery pack, leaving a 12kWh pack, still enough to source 8.8kWh and leave margins on the edges (though this is a 73% DoD, as DoD rises it will accelerate the reduction of battery capacity). It appears that they’ll probably fall about 1,000 cycles short of what they would need, however that is the worst-case scenario – the 55% DoD is a upper bound and many times drivers may just being going out for a short drive and it would be to their benefit to recharge it when they return, since reducing their average DoD will prolong battery life and performance.
A life of 2,750 cycles at 40 miles per cycle would mean 110,000 miles – 40,000 mile short of the 150,000 mile warranty. This would require someone to drive exactly 40 miles per charge, and then charge it up, then drive 40 miles again, never using the gasoline engine. This isn’t too practical in the real world – either owners will always drive on electricity (reducing the average depth of discharge and increasing the battery cycle life) or they’ll be driving some miles on gasoline and not affecting the battery but still ticking miles off the warranty.
In the worse case scenario, I would expect that even at two charges per weekday (which would be exceedingly rare) and one per weekend day, the amount of time to get to 110,000 miles would be four and a half years (25,000 miles per year). By 2015, batteries should be somewhat cheaper ($500 per usable kWh, rather than $700, with a total pack price of $5,500), and the replacement batteries should last sufficiently long as to not need replacement before the original warranty period is up since the warranty doesn’t reset, rather the batteries will just need to get through the remaining 40,000 miles on the warranty.
If the Volt shell, engine and generator cost $25,000 (the cost of a high end Civic), the battery being another $8,000, the total vehicle cost is only $33,000. These numbers however, don’t include the additional labor since the vehicle isn’t being mass produced initially – only 10,000 units (maybe) for the first year, and battery packs will be assembled mostly by hand (see the 2nd to last paragraph) and more automation will be added to ramp production. It also doesn’t include any warranty, dealer markup, delivery, etc. If GM has to provide a second battery to 20-30% of Volt owners before the warranty is up, that could add another $1,500 to the cost of each car. It also doesn’t include any money to pay off the many years of research and development that have gone into the car, the battery testing lab, etc.
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