AUSTIN, Texas — The country’s advanced battery makers waited years - in some cases, decades - for the day electric vehicles would go mainstream.

Yet now, even as cars such as the Nissan Leaf and the Chevrolet Volt are becoming recognizable brands, two of the country’s top lithium-ion battery makers are teetering on the brink of insolvency.

Austin-based Valence Technology Inc. tipped over the edge Thursday with the announcement that it had filed for Chapter 11 bankruptcy protection and was negotiating a new source of funding that would boost its working capital and allow it to continue operating.

The Austin battery maker’s announcement came less than a week after Massachusetts-based A123 Systems Inc. told investors that it had about five months of cash remaining for its operations and would move to raise more funding in the interim.

A123 had raised $378 million through an initial public offering in 2009. The following year, it hauled in a $249 million grant from the Obama administration. Five months from now, who knows? A123 said it was raising $39 million to handle its pending cash crunch, but the company could still join Solyndra, the now-defunct Silicon Valley solar technology company, on a scrap-heap of government-subsidized green-tech bankruptcies.

If Valence’s 23 years of experience and the size of the plug-in electric car market offer a sign of what’s to come, both U.S. battery makers will need a lot more cash and time before their income can support their expenses.

“Lithium batteries are difficult to manufacture,” said Donald Saxman, an analyst at BCC Research. “You could make lead-acid batteries in your garage. ... For lithium, you need a clean room, (and) there are lots of quality assurance problems.” Once a company works through the engineering manufacturing quality issues, it still needs a market that can buy enough battery systems to start paying off those costs.

Barring that, it needs subsidies or investors who have a lot of money and a long-term view, Saxman said.

A123 got the former. Valence has the latter: California billionaire Carl Berg, the company’s chairman and the holder of about 44 percent of the company’s stock.

In a regulatory filing, Valence said that the Nasdaq exchange had suspended trading of its stock and noted that it currently owes Berg and his companies $69.1 million in loans.

Berg, who abstained from the board’s vote to file for bankruptcy, stands to lose much of the more than $100 million he’s invested in the company since it launched in 1989.

There was no clear indication that Berg was withdrawing his support of Valence, but it’s clear neither Valence nor A123 can count on a large enough revenue jump in the foreseeable future.

Plug-in electric car prices have dropped, and the number of models has mushroomed over the past 18 months, but full-electric cars still make up less than 1 percent of total vehicle sales.

In 2011, fewer than 18,000 plug-in electric vehicles were sold in the United States, said Dave Hurst, senior analyst at Pike Research. Hurst projects about 48,000 plug-in electrics to sell in the U.S. this year - compared with a forecast for 13.3 million cars and light trucks overall.

Cost and range anxiety continue to plague full-electric vehicles, and by extension the lithium-ion battery makers.

“The technology of the lithium battery has reached a fairly mature stage,” said John Goodenough, an engineering professor at the University of Texas and the godfather of lithium-ion battery technology. “But they have to get the cost down and capacity up so people can have a longer driving range.” That “range anxiety” - the idea that you might run out of power halfway home - has pushed many people toward hybrids, which are cheaper and still clean enough to salve most consumers’ environmental conscience. Most hybrids use a different type of battery technology.

And for full-electric cars, the battery remains the single most costly component.

In April, Ford CEO Alan Mulally said the battery pack for the Ford Focus electric costs between $12,000 and $15,000. The car itself starts at around $40,000.

That could start to change. A recent report by McKinsey & Co. suggested that battery costs could fall from $600 per kilowatt hour today to about $200 by 2020.

But to date, sales of lithium-ion batteries for full-electric cars and other industrial applications - such as large-scale electricity storage - haven’t produced the volumes many in the industry hoped for or expected, said Brittany Gibson, another analyst at Pike Research.

And making matters more difficult, the big Asian competitors, such as Sony, Sanyo and Samsung, are large and more diversified, Gibson said, so they “can weather the period they’re in now as they wait for a lot of commercial projects to take off.”