Tesla expects to raise nearly $1.8bn (£1.4bn) by selling "junk" bonds to private investors - even more than the electric car-maker aimed for when it announced the offering this month.
The firm said the money will keep its balance sheet steady as it ramps up manufacturing of its newest car.
Tesla aims to make 5,000 of its mass market Model 3 a week by the end of this year.
It has estimated it is already spending about $100m a week to hit that target.
On 4 August Tesla said was looking to raise $1.5bn by selling bonds, but said on Friday it now expected to raise $1.77bn from the sale.
The fundraising is limited to major institutions and not private investors.
Analysts said Tesla's ability to raise more than $1.5bn indicated an appetite for risk among investors, as low interest rates have limited returns in many other types of investments. High stock market valuations have also made it harder to make a profit.
"Without the proceeds from the note offering, Tesla's liquidity position would be stressed," analysts at Moody's said, warning of risks to potential investors.
Tesla had about $3bn in cash at the end of June, but it spent more than $2bn in the most recent quarter.
The company founded by Elon Musk has frequently turned to investors to overcome persistent operating losses.
Tesla plans to eventually make more than 500,000 of the new Model 3 cars a year at its Fremont factory - or about 10,000 per week.
Moody's said the target was ambitious given the relatively small size of the US electric car market.