Williams will put KERS back on Rubens Barrichello's car at this weekend's Hungarian Grand Prix, after experimenting to see what effect removing it would have in Germany.
The team wanted answers as to whether removing KERS would help with tire degradation, so it elected to try it out at the Nurburgring. After its experience there, however, Williams technical director Sam Michael confirmed on Monday that KERS would be run on both cars.
"We have had doubts over KERS in the past with controlling the brake balance under braking, where you end up with quite a difficult situation," explained Michael. "We always felt in the past that the few times in races where we have turned it off, it has actually been better on rear tire degradation. There is no doubt in qualifying that it is better because it gives you three and a half tenths because you can go out and we don't have to charge KERS for qualifying.
"Some guys are obviously more on top of their changing than we are, so the penalty for running it is something that we thought we could try at this track. We were planning to try and do it here."
The removal of KERS from Barrichello's car also meant that the team could play around more with weight distribution.
"You have to have a body mass that you can then use for weight distribution and center of gravity. What we needed to do was go through a race weekend and see what happens to a car when it is not charging, because when we were at Silverstone and didn't have the blowing we could then switch to a different mode in the engine," Michael explained.
"We could use a lot of the ignition firing to control the braking and it was much better, but we cannot do both, the engine is not capable of doing that. So we cannot have 100 percent blowing and ignition firing, as we can't do the ignition retarding that other teams do. So we can stop the blowing under braking and control the brake balance, or we can do the opposite. It is a bit tricky for us."