It will depend on whether or not your battery is still alive after six years. It most likely is, but you won't be getting anywhere near the full capacity since current (affordable) lithium batteries have a shelf-life of around 6-8 years in no use whatsoever.
Most likely you will have to buy a new battery after 3-4 years, unless you oversize it, but that in turn costs you more money.
A better estimate can be had if you find the specifics of the battery. For example, let's take a 20 kWh set that costs that 18k€ and lasts for 1000 full cycles of 20 kWh and 6 years. By this time the capacity has dropped by 30% from the aging alone, and 30% from the driving alone, to around 50% of the original combined. If we hold that as the cutoff point, we get 90 cents per kWh as the capital cost for storage, and we can further assume e.g. 10 cents per kWh with losses accounted for the electricity.
1€ per kWh used is then compared to the consumption of the car, which can be up to 200 Wh per kilometer, which in turn gives you 20€ for every 100 km. Compare that to the price of gasoline, and for 10l/100km it turns out to be roughly 133% of the price. In this case, you won't break even.
In the case that the battery lasts for 2000 cycles, the cost is obviously halved to 10€/100km and you do break even, but then again that would mean that you have to drive 2000 cycles in roughly 6-8 years, which means 40 000 kWh used and 200 000 kilometers driven, that is, 25 000 kilometers per year or more. It may turn out that the battery dies on you from old age before you can drive it far enough to recoup the investment. It's difficult to drive 25k in a year with a car that only goes around 75 km on a charge on average throughout its lifetime.
Tribroker (guest) 26 Feb 2010 08:47
