But A123 also warned at the time that its current growth rate wouldn’t continue, in large part because Fisker had unexpectedly canceled battery orders. As a result of the canceled orders, which Fisker blamed on oversupply due to delays in production of the Karma, A123 lowered its earnings forecasts for the year by $45 million.  

A123 Systems won’t disclose precisely how much of its business comes from Fisker, but based on the earnings downgrade, one analyst estimates it was about 30 percent last year. A123 Systems will release its financial results for 2011 within a month. It doesn’t expect orders from Fisker to pick up until the spring.

A123 Systems needs as much business as it can get. Even with the revenue growth seen in the third quarter of 2011—up over 300 percent compared to the previous year—it reported losses of $173 million for the first nine months of 2011. One of its most urgent needs is to ramp up production to meet the capacity of its battery factories, which would increase revenue and decrease the cost of making each battery pack. Without orders from Fisker, more of the equipment is sitting idle than the company had expected.

Although less is known about the financial situation of Fisker, a private company, the announcement made this week shows that it was counting on continued government funding. Fisker says the shutdown of work on the factory in Delaware will not affect production of the Karma, which is made in Finland. But the Delaware factory was intended to produce the company’s second car, the yet-to-be-revealed Nina, which will be less expensive than the Karma. Fisker’s business plan involves eventually selling large volumes of the Nina.

A123 does, at least, have significant cash reserves and income from contracts with several automakers, for electricity-grid related projects, and for backup power for businesses. If it can survive this year, its outlook may look better in the years to come, when it has contracts to make more batteries.

Eventually A123 expects its largest customers to account for only 10 to 15 percent of its revenues. That’s about half as much as Fisker does today, according to the analyst’s estimate. “Fisker is a very important customer for A123 in 2011 and 2012,” says Dan Galves, a research analyst at Deutsche Bank. “But A123 has a lot of other contracts growing in 2012 or that are starting up in 2013, which means that Fisker isn’t a critical customer for the company long-term.”