Lotus trackside operations director Alan Permane says the team had a problem with the energy store on its Renault power unit in Bahrain.

Romain Grosjean completed just eight laps on the first day of the second test at the Bahrain International Circuit despite the team having successfully covered 100km during a filming day 10 days earlier. With Renault's power units being blighted by problems at the Jerez test, Permane admitted it was one such problem with the energy store which had affected Lotus on Wednesday.

"Obviously that wasn't the day we wanted to have and there are few conclusions we can draw so far as our running was so limited," Permane said. "It's no secret that we're frustrated as we want to get laps on the board to understand our new car and all the different elements it contains.

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"The power units contain a lot of new technology and certainly we had issues with the energy store unit today. We changed this unit during the course of the day, which is not the work of a moment. Certainly we hope for a better day tomorrow."

Renault is running updated hardware and software in Bahrain but while Caterham alone was able to complete 68 laps, the other three Renault-powered teams - Red Bull, Lotus and Toro Rosso - managed a total of just 27 laps between them.