Consumer fury against big banks is jingling the till at credit unions.

The small not-for-profits, generally viewed as a low-key corner of the financial services business, have been picking up customers who say they're fed up with bank fees and account requirements.

TopLine Federal Credit Union in Maple Grove said it saw a nearly 20 percent increase in new checking accounts in the first three weeks in October. Others say new checking accounts have doubled.

The surge is unprecedented, according to TopLine CEO Harry Carter. He said about a third of the new customers "are volunteering that they're doing it because of the fees charged by larger banks."

The credit unions are capitalizing on what has been a slow-burning anger over the government's 2008 bailout of big banks and what some see as the banks' refusal since then to offer help to cash-strapped customers or loans to anyone without sterling credit.

It's unclear whether the backlash will grow big enough to become something more than an annoyance to the industry's largest institutions, who are now flush with cash. Some analysts think the customers most likely to desert big banks are the least affluent -- and often the least profitable.

But credit union executives say there's no question that they are gaining customers. They're preparing for another wave with the approach of "Bank Transfer Day" -- a grassroots call circulating across the country to boycott banks and shift accounts to credit unions next Saturday.

Apparently launched on Facebook this month by a Los Angeles art dealer who said she'd "had enough," the Transfer Day idea has caught fire. As of Friday, a Facebook page showed about 65,000 people would participate, and another 13,000 saying they might.

Consumers have complained for years about bank fees. The 2008 taxpayer bailout "added insult to injury," said Pamela Banks, senior policy counsel for the Consumers Union in Washington, D.C.

Then came this year's battle over how much banks can charge retailers in debit card "swipe" fees. Many big banks said in response to the new, lower limits on those fees that they would consider charging customers to use the cards.

However, the industry has been beating a hasty retreat from those plans this fall, in what seems at least a tacit admission that customers won't stand for it.

This past week, Wells Fargo and J.P. Morgan Chase said they won't follow through with previous plans to charge people for using their debit cards when their pilot programs run out. Wells Fargo began its test in five states on Oct. 14, charging a $3 fee for debit purchases. On Friday, Wells said it was canceling the test program.

In Minnesota, TCF announced last week that it would not charge a specific monthly fee for debit cards. TCF is charging a $9.95 monthly maintenance fee for checking account customers who don't meet certain requirements.

Minneapolis-based U.S. Bancorp, too, said it doesn't plan to charge customers monthly debit card fees, but it has ended its debit rewards program. This summer it started charging checking customers $6.95 to $8.95 a month if they don't meet certain requirements.

TCF unsuccessfully sued the Federal Reserve in a bid to stop the new debit limits, warning that consumers would end up paying for it.

A surge of new accounts

How much of the uptick in business at credit unions can be tied to the debit card issue is impossible to say, but credit union executives say customers are angry about fees in general.

Even the Minnesota Catholic Credit Union, with just $25 million in assets, is seeing more business. The church-based credit union in Little Canada has doubled the number of new checking accounts in the past six months.

CEO David Sawin said he's surprised, and chalks it up to the bank fee fracas.

"Now they're saying 'I don't care that I've been with my bank for 30 years, I'm coming over to you because they've pushed me too far,'" Sawin said.

"We didn't advertise," Sawin added. "We weren't pushing it."

Other credit unions, however, are.

St. Paul-based Affinity Plus Federal Credit Union, one of the state's largest credit unions with $1.5 billion in assets, has ramped up its edgy "Ditch Your Bank" ad campaign.

The campaign, by Risdall Marketing Group of New Brighton, has been running for a year. But it shifted last spring from poking at the industry in general to directly attacking bank fees, said Kyle Markland, Affinity Plus' CEO.

"We just felt that it was time that somebody had to take a more aggressive stand to say there's an alternative out there," Markland said.

Television spots that started running last spring show customers in an imposing bank being stripped of their clothes. The voice: "Too-big-to-fail banks are always finding new fees, charges and rate increases. How much more do you want them to take?"

Earlier this month, Affinity Plus took a swing at Wells Fargo with billboards trumpeting: "More debit card fees? That's stagecoach robbery."