'Low revs may cause overheating'

Renault believe the alternator failures that afflicted Sebastian Vettel during the Italian Grand Prix weekend may have been caused by the units overheating at low revs.

The double World Champion ground to a halt during final practice at Monza, whilst his hopes of a third straight title were dealt a blow in the race when the same issue struck the Red Bull again.

Similar problems cost the German a likely victory in Valencia, where he retired from the lead of the race - whilst Lotus driver Romain Grosjean, who is also powered by Renault, retired with the same issue.

Investigations into the exact cause are still being carried out, however, the engine manufacturer's Deputy Managing Director, Rob White, believes the parts may simply be overheating at low revs.

That could be a serious issue in Singapore next time out, as the twisty nature of the street circuit means the cars will regularly be running at low revs.

"Our investigations after Valencia revealed potential overheating problems at low RPM," White was quoted by Autosport.

"We developed a revised alternator that was validated on the test bench and trialled at Spa by Red Bull and Lotus - the teams that suffered the issues in Valencia - and no issues were found.

"The fundamental change was to lengthen the alternator stator and rotor by 10mm to increase its electrical power generation capacity where current demand exceeded the alternator's capacity to supply.

"With this new spec we can deliver around 30 per cent more current to try to address the problems at low RPM.

"In each case it was a brand new example of the new spec. After the incidents in FP3 and qualifying, we changed the alternators on the Red Bull of Vettel and the Lotus of d'Ambrosio. The race incident was therefore a further early life failure.

"Other parts have achieved much higher mileages; it is therefore a priority to discern the significant differences between the two. The situation is not acceptable; we must address the problem for Singapore."