BP said it started a second system to siphon oil from its Gulf of Mexico leak on Wednesday, a day  after the U.S. government massively raised its estimate of the flow rate from the ruptured well.

BP also said its containment cap system installed at the leak on June 3 collected 10,440 barrels of oil on Tuesday, lower than previous days due to a five-hour shutdown after lightning started a fire on the drillship collecting the oil.

The undersea leak gushed unchecked during the shutdown, the energy giant said.

The cap system, which follows a string of unsuccessful efforts by BP to contain the spill, had been collecting more than 15,000 barrels a day since June 8, with a high of 15,800 barrels on June 9, according to BP figures.

The cap system has collected a total of 160,400 barrels of oil since it was installed on June 3, BP says. A live video feed on BP's website shows an undetermined amount of oil gushing from under the cap and three open vents on top of it.

The cap system's success is dwarfed by the overall spill since a rig explosion on April 20 that triggered the well rupture and the worst oil spill in U.S. history.

On Tuesday, a team of U.S. scientists raised their high-end estimate of the amount of oil flowing from the well by 50% to between 35,000 and 60,000 barrels (1.47 million gallons to 2.5 million gallons/5.56 million liters to 9.5 million liters) per day.

The estimated range includes the oil being captured.

That team initially estimated the leak at 12,000 to 19,000 barrels per day and last week increased that to 20,000 to 40,000 barrels per day.

Switching Caps

The cap system can handle up to 18,000 barrels a day of oil, which is the maximum processing capacity of Transocean's drillship collecting the crude a mile (1.6 km) above the leak, BP said.

The second system that started on Wednesday is intended to increase collection capacity to 28,000 barrels a day, BP said. Its addition is one of several enhancements and changes to eventually push collection capacity to 80,000 barrels a day next month, according to BP's plan submitted to the U.S. Coast Guard late on Sunday.

Part of that upgrade will involve switching out the current cap, which sits on a severed pipe that juts out from a piece of equipment that sits atop a failed blowout preventer.

The new cap will be bigger with a seal designed to contain more oil, according to BP.

"At that point we are pretty well assured there should be minimal leakage around that wellhead," Coast Guard Admiral Thad Allen, the top U.S. official overseeing the spill response, told reporters at a White House briefing on Wednesday.

Allen and BP have both said oil will leak unchecked from the well while uncovered during the cap switch.

All oil collected by the second system will be channeled to a service rig at the surface, the Helix Q4000. That oil will be burned off because the rig has no storage or processing capability.

"When measurements are available for volumes of oil and gas being flared by the Q4000, this information will be added to the updates on BP's website," the company said.

The Q4000 system is reusing seabed equipment installed in May for BP's failed "top kill" effort to smother and plug the leak, the company said.

The top kill involved pumping heavy drilling fluid through hoses connected to a failed blowout preventer and into the well. Now that system of hoses and pipes are pulling oil and gas from the well to the Q4000, BP says.

The company is drilling relief wells that it hopes will definitively halt the spill in August.