Bitcoin backed credit card offers 7.99% rate Aven, a Silicon Valley fintech with more than 100,000 customers that offers a credit card grafted onto a home equity line of credit (HELOC), is launching a bitcoin-backed card. The new card lets consumers pledge bitcoin as collateral to access a credit line of up to $1 million over a term of up to 10 years. Its average percentage interest rates (APRs) range from 7.99% to 11.99%, notably lower than the average U.S. credit card rate of 21.52%, according to the Federal Reserve. To use Aven’s new card, which became available today, customers must agree to have their bitcoin transferred to South Dakota-based BitGo, the cryptocurrency custody company Aven partners with. Aven requires the loans to be overcollateralized–people can’t borrow more than the value of the bitcoin they pledge. Customers’ interest rates depend on how much collateral they put up.…